Crop life tables for appraisal of pest injury to tomatoes

MISSING IMAGE

Material Information

Title:
Crop life tables for appraisal of pest injury to tomatoes
Physical Description:
Book
Language:
English
Creator:
Alvarez Rodriguez, Jose Alonso, 1937-
Publication Date:

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
The University of Florida George A. Smathers Libraries respect the intellectual property rights of others and do not claim any copyright interest in this item. This item may be protected by copyright but is made available here under a claim of fair use (17 U.S.C. §107) for non-profit research and educational purposes. Users of this work have responsibility for determining copyright status prior to reusing, publishing or reproducing this item for purposes other than what is allowed by fair use or other copyright exemptions. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder. The Smathers Libraries would like to learn more about this item and invite individuals or organizations to contact the RDS coordinator (ufdissertations@uflib.ufl.edu) with any additional information they can provide.
Resource Identifier:
aleph - 20492326
oclc - 2896501
System ID:
AA00026358:00001


This item is only available as the following downloads:


Full Text











CROP LIFE TABLES FOR APPRAISAL
OF PEST INJURY TO TOMATOES






By



Jose Alonso Alvarez Rodriguez




















A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY















UNIVERSITY OF FLORIDA

1977
















ACKNOWLEDGMENTS



I express my sincere gratitude to Dr. Sidney L. Poe (Chairman

of the Committee), who directed the present study, for his criticism,

assistance, and enthusiastic encouragement in the preparation of this

dissertation.

Appreciation is extended to Ur. Vernon G. Perry, Dr. Reece I.

Sailer, and Dr. Stephen R. Kostewicz for their advice and critical review

of the dissertation and for serving as members of the Supervisory

Committee. Also, I thank Dr. Robert E. Waites for his help in the pre-

paration of the land for the experiments. Gratitude is also expressed to

Drs. Robert E. Woodruff, Frank M. Mead, Howard V. Weems, Jr., and Eric E.

Grissell of the State Department of Agriculture and Consumer Services,

Division of Plant Industry, Bureau of Entomology, for their help in the

identification of species. Thanks are also due to the "Instituto

Colombiano Agropecuario: for financial support during the period of my

graduate study.

Finally, a very special gratitude is extended to my wife,

Lilia, my children Carlos, Julio, and Luis and to my family who provided

encouragement, affection, and moral support.














ii
















TABLE OF CONTENTS

PAGE

ACKNOWLEDGMENTS . . . . . . . . . . . . ii

LIST OF TABLES . . . . ... . . . . . . .v

ABSTRACT . . . . . . . . . . . . . . vii

INTRODUCTION. . . . . . . . . . . . . ... 1

LITERATURE REVIEW . . . . . . . . . . . . 3
Life Tables . . . . . . . . . . . . . 5
Tomatoes and Cultural Practices . . . . . . . . 8
Tomato Pests. . . . . . . . . . . . . . 11
Insects . . . . . . . . . . . .. .11
Soil insects. . . . . . . . . . . 11
Sucking insects . . . . . . . . . . .11
Foliage insects . . . . . . . . . . 12
Fruit and Foliage insects . . . . . . . .. 13
Diseases . . . . . . . . . . . . 17
Nematodes . . . . . . . . . . . .. 19
Weeds. . . . . . . . . . . . . .. 20

MATERIAL AND METHODS. . . . . . . . . . . ... 21
Experiment 1 1975 . . . . . . . . . . .. 21
Experiment 2 1976 . . . . . . . . . . . 26

RESULTS . . . . . . . . . . . . . . . 28
Experiment 1 1975 . . . . . . . . . . . 28
Management Plot. . . . . . . . . . . ... 28
Life table. ....... . . . . . . . 28
Economic analysis . . . . . . . . ... 32
Insect populations. . . . . . . . . .. 32
Commercial Plot. . . . . . . . . . . ... 34
Life table. . . . . . . . . . . ... 34
Economic analysis . . . . . . . . . . 36
Insect populations . . . . . . . . .. 38
Check Plot . . . . . . . . . . . . 38
Life table . . . . . . . . . . .. 38
Economic analysis . . . . . . . . . . 40
Insect populations . . . . . . . . .. 42
Experiment 2 1976 . . . . . . . . .. . . 42
Management Plot. . . . . . . . . . . . 42
Life table. . . . . . . . . . . . 42
Economic analysis . . . . . . . . . . 43
Insect populations. . . . . . . . . . 46




iii








TABLE OF CONTENTS Cont'd.

PAGE

Commercial Plot . . . . . . . . . . . 47
Life table .. . . . . . . . . . . . 47
Economic analysis. . . . . . . . .... . 49
Insect populations . . . . . . . . . . 49
Check Plot. . . .. .. . . . . . . . . 51
Life table .. . . . . . . . . . . 51
Economic analysis. . . . . . . . . . . 53
Insect populations . . . . . . . . . . 55

DISCUSSION . . . . . . . . . . . . . . . 83
Transplant Period. . . . . . . . . .. . . . 83
Bloom Period . . . . . . . . . . . . . 86
Fruit Set Period . . . . . . . . .. .. . . 86
Maturation Period . . . . . . . . . . . .. 87
Insect Populations . . . . . . . . . . . . 89
Economic Analysis . . . . . . . . . . . ... 91

CONCLUSION . . . . . . . . . . . . . . 92

REFERENCES CITED . . . . . . . . . .. . . 96

BIOGRAPHICAL SKETCH. . . . . . . . . .. . . . 105

































iv















LIST OF TABLES

PAGE

1. Crop life table for tomatoes, variety "Walter," . . . .
Gainesville, Fla. 1975 (Management plot I) . . ... 30

2. Estimated dollar loss by major mortality factor on
tomatoes, 1975 (Management plot I) . . . .. .. . 31

3. Crop life table for tomatoes, variety "Walter,"
Gainesville, Fla. 1975 (Commercial plot II). . . ... 35

4. Estimated dollar loss by major mortality factors on
tomatoes, 1975 (Commercial plot II) . . . . ... .37

5. Crop life table for tomatoes, variety "Walter,"
Gainesville, Fla. 1975 (Check plot III). . . .. . .39

6. Estimated dollar loss by major mortality factors on
tomatoes, 1975 (Check plot III) . . . . .. . .41

7. Crop life table for tomatoes, variety "Walter,"
Gainesville, Fla. 1976 (Management plot I) . . . ... .44

8. Estimated dollar loss by major mortality factors on
tomatoes, 1976 (Management plot I) . .. . ....... 45

9. Crop life table for tomatoes, variety "Walter,"
Gainesville, Fla. 1976 (Commercial plot II). . . . ... 48

10. Estimated dollar loss by major mortality factors on
tomatoes, 1976 (Commercial plot II) . .. . . . 50

11. Crop life table for tomatoes, variety "Walter,"
Gainesville, Fla. 1976 (Check plot III). . . . . ... 52

12. Estimated dollar loss by major mortality factors on
tomatoes, 1976 (Check plot III) . . . . . . .. 54

13. Total fruits harvested and damaged by insects (I),
diseases (D) and mechanical (M) per plot. 1975 . . ... 56

14. Total fruits harvested and damaged by insects (I),
diseases (D) and mechanical (M) per plot, 1976 . . ... 57

15. Cost and benefits of alternative control methods
for tomatoes . . . . . . . . ... .. .. . 58



v









TABLE PAGE

16. Total numbers of Myzus persicae (Sulzer)
per plot, 1975 . . . . . . . . . . . 59

17. Total mines of Liriomyza sativae Blanchard per
plot, 1975. . . . . . . . . . . 60

18. Total larvae (1) and eggs (2) of Heliothis spp.
per plot, 1975 . . . . . . . . . . 61

19. Total larvae of Spodoptera spp. per plot, 1975. . . . 62

20. Total numbers of Myzus persicae (Sulzer) per
plot, 1976 . . . . . . . . . . . 63

21. Total mines of Liriomyza sativae Blanchard per
plot, 1976. . . . . . . . . . . . .. 64

22. Total larvae (1) and eggs (2) of Heliothis spp.
per plot, 1976 . . . . . . . .... . .. . 65

23. Total larvae of Keiferia lycopersicella (Walsh.)
per plot, 1976 . . . . . . . . . . . 66

24. Total larvae (1) and eggs (2) of Manduca sexta (Joh.)
per plot, 1976 . . . . . . . . ... ... 67

25. Pit-fall trap captures of arthropods in Management (M),
Commercial (C) and Check (Ch) plots of tomatoes through-
out nine sampling weeks. Gainesville, Fla. 1976. .. .... 68

26. Total numbers of arthropods collected by pit-fall traps
in Management (M), Commercial (C) and Check (Ch) plots of
tomatoes during nine sampling weeks. Gainesville, Fla.
1976. . . . . . . . . . . . . . 75

27. Estimated dollar loss by major mortality factors on
tomatoes, 1975 (Management plot I). . . . . ... 76

28. Estimated dollar loss by major mortality factors on
tomatoes, 1975 (Commercial plot II) . . . . .. 77

29. Estimated dollar loss by major mortality factors on
tomatoes, 1975 (Check plot III) . . . . . . 78

30. Estimated dollar loss by major mortality factors on
tomatoes, 1976 (Management plot I). . . . . ... 79

31. Estimated dollar loss by major mortality factors on
tomatoes, 1976 (Commercial plot II) . . . . . 80

32. Estimated dollar loss by major mortality factors on
tomatoes, 1976 (Check plot III) . . . . . . 81

33. Costs and benefits of alternative control
methods for tomatoes. . ....... . . . . 82


vi













Abstract of Dissertation Presented to the Graduate Council
of the University of Florida in Partial Fulfillment of the Requirements
for the Degree of Doctor of Philosophy



CROP LIFE TABLES FOR APPRAISAL
OF PEST INJURY TO TOMATOES



By


Jose Alonso Alvarez Rodriguez

March 1977



Chairman: Dr. Sidney L. Poe
Major Department: Entomology and Nematology

Qualitative, quantitative and economic effects of mortality and

cull factors on tomato (Lycopersicon esculentum Mill.) were studied and

used to elaborate a crop life table as an approach to identify deter-

minant factors in the management of tomato pests. Tomatoes were grown

under Management, Commercial, and Control strategies in 1975 and 1976.

During the Transplant period of tomato growth, cutworm (Feltia

spp.), mole cricket (Scapteriscus spp.) and damp-off (Rhizoctonia spp.)

were identified as the major mortality factors. Collectively, cutworms,

mole crickets and damp-off, during the Transplant period, affected 9.0%

of the plants and reduced the potential income by $205 per acre.

Damp-off also caused additional injury during the Bloom and Fruit

Set periods. The average loss was 1.6% and $41 per acre.





vii










Heliothis zea Boddie, Spodoptera spp., Keiferia lycopersicella

(Walsh.), Manduca sexta (Joh.), soft-rot (Bacteria), blossom end rot,

and mechanical damage, were the factors responsible for culled fruits

during Maturation period. The damage caused by these factors was

conditioned in part by the time and duration of the damage and also by

the high or low economic value of the crop and by the control strategy

followed. Averaged economic impact of these factors for the two year

period was 24.0% for the Pest Management strategy, 19.0% for the

Commercial strategy and 39.0% for Check strategy.

The economic analysis indicates that for the two year term and

with the hazards occasioned by the inappropriate use of insecticides

in mind, Management strategy appears to be an approach to handle tomato

pests as sound as current conventional.

The results of this study show that life table analysis is useful

in identifying and evaluating pests of tomatoes as well as for determin-

ing strategies most suitable for optimum tomato production. The format

of life table permits not only an insight into the effects of different

mortality and cull factors, but a direct accounting of production

losses.



















viii
















INTRODUCTION



The tomato (Lycopersicon esculentum Mill.) ranked second in value

and third in acreage among the 22 principal commercial vegetables culti-

vated in the U.S.A. in 1973 (Anonymous, 1975). In Florida, the tomato

is considered the most important vegetable crop, not only because of

annual value but also because of the acreage planted ($148,700,000 and

31,500 respectively during 1975) (Anonymous, 1974).

As is true for most cultivated crops, the tomato plant is attacked

by several groups of pests insects, plant pathogens, nematodes, and

viruses which individually and collectively at one time or another con-

stitute serious threats. In many cases these pest species, along with

competition from weeds, are limiting factors to tomato production (Porte

and Wilcox, 1963). Growers are forced to apply chemicals, usually on a

routine schedule, to eliminate much of the uncertainty caused by the

threat of pests in tomato production.

Environmental problems created by misuse of chemicals, resistance,

eruption of secondary pests, regulations by the Environmental Protection

Agency, limited product availability, and increased cost of chemicals,

provide impetus to develop alternative approaches to pest control.

Approaches that maximize production per unit area at minimum cost per

unit of production and minimize chemical applications are needed. Such

approaches must be based on a sound understanding of all components of

the crop system (agroecosystem). Within the crop system the plant as

well as its environment and pests, are dynamic sub-systems. Effective



1






2

management of the system depends on knowledge of the interrelationships

of these sub-systems.

Prior to 1966, 20% of the tomato production costs in Florida were

expended in controlling pests; this value increased to 25% during the

last decade (Brooke, 1976). Although much information is available con-

cerning specific controls for the various pests of tomatoes, there is

little information on actual economic losses caused by the pest complex.

No approach based on integrated management of pest populations affecting

this crop has been implemented on a commercial scale.

Pest management can only be justified in terms of its net contri-

bution to human values, not only from the economic point of view, but

from the biological, the ecological, and the social. Pest management

consists of a combination of processes including acquisition of infor-

mation from the agroecosystem and decision-making as well as the taking

action to manage pest situations (Ruesink, 1976).

Economic thresholds are considered one of the basic elements of

a sound pest management program. Reliable information on crop losses due

to destructive agents aims to establish increase profit, obtainable when

these agents are controlled at an acceptable economic cost.

This study was undertaken to determine, quantitatively, crop

losses caused by destructive factors affecting tomato production. The

methodology consisted basically of periodic sampling procedures intended

to determine the main crop mortality factors, and the population dynamics

of certain pests, especially insects. Experiments and data analyses

were designed to construct a crop life table for tomatoes.
















LITERATURE REVIEW


Pest management has gradually gained prominence during the past

decade as a practical and sensible way to deal with pest problems.

Pests are living organisms which occur in large enough numbers to harm

man's property or values. Thus, population density is therefore a matter

of primary concern to pest management (Geier and Clark, 1960, Huffaker,

1974). Moreover, populations exist as components of communities at various

densities in a variety of ecosystems (Clark, et al., 1967). An ecosystem

is a system composed of living organisms and non-living environmental

factors interacting to produce an exchange of matter and energy in a

continuing cycle (Odum, 1971). The parts of an ecosystem which determine

the existence, abundance and evolution of a particular population are

collectively called the life system of the population. It is usually

composed of both the population and its environment (Clark et al., 1967).

Pest management has been defined as "the intelligent reduction

of pest problems by actions selected after the life systems of the pests

are understood and the ecological, social and economic consequences of

these actions have been predicted, as accurately as possible, to be in

the best interest of mankind" (Rabb, 1970). Pest management is now

generally thought of as a final goal achieved through intelligent

direction of effort over an extended period. The goal is threefold:

1) manipulation of available resources to hold pest populations below

economic damage levels; 2) avoid or reduce disruption of the environment

by decreasing the need for protective use of pesticides and 3) assure




3







4

crop production levels needed to meet the needs of an increasing human

population. From these points of view, pest management has a broad

ecological, economic base and two fundamental guiding pricniples. The

first is to consider the life systems of pests and the second principle

is need to establish and utilize critical injury levels (Geier and Clark,

1960, Smith, 1969, Rabb, 1970, Huffaker, 1974, Ruesink, 1976).

Agroecosystems are man-influenced agricultural crop systems. Due

to their non-natural state they differ markedly from natural ecosystems

(Solomon, 1972, Springett, 1972). While less complex than natural

systems, agroecosystems are very complex and dynamic in function. They

are intensified systems in that different resources (inputs) are inte-

grated to maximize agricultural production per unit of area. Many of

the technologies developed to achieve this goal have resulted in increased

plant pest problems (Apple, 1972). Increased pest problems, in many cases,

created by crop cultural technology have required routine application of

chemicals in order to maintain production. The occurrence of resistance,

environmental contamination by chemicals, residues, resurgence of pests,

and eruption of secondary pest populations have created serious problems.

To deal with these problems pest control must be founded on a more sound

ecological basis (Smith, 1970).

Crop yield and quality have been shown to be determined by several

factors: variety, soil, fertilizer, environmental conditions (temperature,

moisture, radiation), cultural practices, and in greater or lesser degree

by the pests (insects, diseases, nematodes, weeds, etc.). In under-

taking pest control actions with chemicals, the farmer attempts to reduce

damage caused by pest populations, to insure the revenue from his crop by

assuring harvest of all potential yield. The use of pesticides rarely

increases yield, rather pest control serves to defend or protect what






5


would be produced in the absence of pest competition (Ordish, 1962,

Southwood and Norton, 1972, Luckman and Metcalf, 1975, Headley, 1975).

In reality farmers are faced with uncertainty (risk) concerning weather

and possible damage by pests so chemicals are used to reduce the uncer-

tainty and thus to protect the capital investment. On the other hand,

populations of both pest and non-target species are functional parts of

agroecosystems and any alteration of the environment should be carefully

monitored in order to avoid disruptive effects that could result in

disastrous consequences (Rabb et al., 1974).

For pest management to be on a sound ecological basis and to be

helpful in reducing uncertainty, basic information is required in crucial

areas such as population dynamics of the pests and the economic thresh-

olds of the crop systems. This information will provide a basis for de-

cisions with respect to management alternatives that either maximize or

complement the action of those processes that reduce pest populations

below economic levels (Campell, 1971, Way, 1972, Varley et al., 1974).

To get the needed information, an interdisciplinary approach has been

emphasized in which the simultaneous study of all involved factors must

be integrated (Benham, 1972, Bar, 1972, Giese et al., 1975).



Life Tables


It is evident that there should be a basic understanding of the

relationship between pest infestation levels and actual monetary crop

losses. Therefore, it is necessary to determine economic thresholds,

that is the maximum pest population that can be tolerated at a partic-

ular time and place without a resultant economical unacceptable crop

loss (Stern et al., 1959, Luckman and Metcal, 1975, Way, 1972, Smith,

1969, 1971). Headley (1975), emphasized that this concept is an







6

application of standard economic costs and return analysis, or in other

terms, cost/benefit analysis. Chiarappa et al. (1972) stressed the fact

that little reliable information on the magnitude of crop losses is

available. Crop loss information can be used both to reduce the risk

faced by the farmer and to eliminate unnecessary use of chemicals.

Methodology for cost/benefit analysis can be found elsewhere (Smith, 1971,

Southwood and Norton, 1972, Headley, 1975).

Crop life tables have been used as a tool for cost/benefit

analysis and Luckman and Metcalf (1975), emphasized that such an approach

provides excellent guidelines in the planning of pest management. Crop

life tables are modified from the life table concept of ecology. A life

table is a concise summary of certain characteristics of a population;

it states for every interval of age, the number of deaths, the survivors

remaining, the rate of mortality and the expectation of further life

(Deevey, 1947).

Hett and Loucks (1968) used life tables to analyze the dynamics

of three species of forest trees. They concluded that the three species

examined have a negative exponential distribution of numbers with age,

indicating relatively constant germination survival, mortality rates and

population structure over the ages studied. The changes in survivorship

rates appear to be a result of differences in shade tolerance between the

three species. Waters (1969) demonstrated that crop life tables provide

a logical format for the full record of birth, growth, and death of trees

in forest stands. Mortality and other losses in volume and value due to

destructive agents were recorded by cause at the time or in the period

they occurred.





7


Harcourt (1970) made the first use of life tables for analysis

of pest damage and cost/benefit in cabbage pest management in Canada.

Under non-treated conditions he found that young plants have highest

mortality, and that cutworms, cabbage caterpillars, and root maggots were

major mortality factors. Taken together, insects caused losses of

$317.47/acre, diseases $34.18/acre, and miscellaneous factors (mechanical

damage, rodents, weather, etc.) $26.01/acre. Operating profit at $436.30/

acre was just over 50% of potential revenues at the time of planting

($813.96/acre).

Crop life tables differ from insect life tables by: 1) the survi-

vorship record is obtained from periodic sampling of the same population

and the same individuals; 2) the population (and, therefore, the crop life

table) is "closed-ended," i.e., there is no recruitment through births or

immigration, and the population is terminated by a harvest; 3) the per-

centage values for successive mortalities are in absolute, rather than

relative terms, i.e., all are calculated from the number of plants alive

at the start (Harcourt, 1970).

Napompeth and Nishida (1974) reported that the main factors causing

damage in sweet corn were: 1) lack of pollination and 2) corn earworm.

Loss of revenue per acre was $1,471 and $500, respectively. The same

authors concluded that there are two ways to utilize crop life tables:

1) assessment of actual mortality of plants during the growth period and

2) assessment of losses or mortality in terms of dollar value of the crop.

Hall (1974), utilizing crop life tables in apples, found that without

insecticides fruit quality and yields were reduced by 45% and 85%, re-

spectively. When injury from insects or diseases was severe, grading

required extra personnel and the speed of this operation was reduced






8


resulting in increased production costs.




Tomatoes and Cultural Practices


The tomato, Lycopersicon esculentum Mill., a member of the family

Solanaceae, is a native of tropical America. Plants are herbaceous,

procumbently branched and partially erect, bearing fruits, a berry, in

clusters. There are determinate and indeterminate growth types. The

size and shape of the fruit varies with the cultivar.

It is a warm-season plant and shows a wide climatic tolerance and

can be grown in the open wherever there are more than 3 months of frost-

free weather. It thrives best when the weather is clear and rather dry

and temperatures are uniformly moderate (65 F to 850F). Plants are

usually frozen at temperatures below 320F and they do not increase in size

at temperatures above 950F. If the night temperature stays above 850F,

the fruits do not become completely formed (Jones and Rosa, 1928,

Thompson, 1949).

Methods of plant growing differ. Tomato plants are started either

in special plant-growing structures or by planting directly in the field.

Methods of starting plants include: hotbeds; cold-frames; open-beds;

greenhouses and direct seeding in the field. Setting plants in the

field is done either by hand or by transplanting machinery. Tomato

seedlings should be transferred to the field with as little shock as

possible. The preservation of a large amount of the original root system

is probably unimportant. If the plants are "hardened" to prevent immedi-

ate desiccation, they will form a new absorption system very quickly.

The planting distances vary with the locality and methods of cultivation

from 1-12 to 4 feet apart in rows that are from 3-1/2 to 6 feet apart






9


(Jones and Rosa, 1928, Porte and Wilcox, 1963, Kelbert et al., 1966,

Stephens, 1973).

A number of cultural practices for tomato growing have been

developed through the years. Unless mulch is used, frequent shallow

cultivation should be given as often as is necessary to stir the soil

and to control weeds (Thompson, 1949, Porte and Wilcox, 1963).

The amount and kinds of fertilizers to apply economically for

the tomato crop depend not only upon the available fertility of the soil,

but also upon the organic content, moisture supply, season, cropping

system, cultivar, etc. For best production, however, special attention

must be paid to the time of application and sources of nitrogen, phos-

phorus and potassium (5 pounds of nitrogen, 2 pounds of phosphorus and

8 pounds of potassium are required to produce 1,000 pounds of tomatoes

(Kelbert et al., 1966). In Florida, polyethylene mulched crops are given

a total of 200 to 400 pounds of nitrogen, 100 to 450 pounds of phosphorus,

and 400 to 550 pounds of potassium per acre in addition to minor elements

and lime to bring the soil reaction to pH 6.5 (Jones and Rosa, 1928,

Thompson, 1949, Wilcox and Langston, 1960, Geraldson, 1963, Wilcox et al.,

1962, Marvel and Montelaro, 1966, Jaworski, 1965, Murphy, 1965, Kelbert

et al., 1966, Bryan and Strobel, 1967).

Important factors in growing tomatoes are an ample water supply

and facilities for rapid drainage after heavy rains. Sufficient moisture

should be present for germination or quick recovery of transplants and to

keep the plants growing well without wilting. Excess of water during

harvesting increases cracking of the ripening fruits (Porte and Wilcox,

1963, Kelbert et al., 1966, Locascio and Myers, 1974).

Any material used to cover the soil around the plants is called






10


a mulch; presently in Florida polyethylene plastic mulch is the most

used material. As with any cultural practice, plastic mulch has advan-

tages and disadvantages as pointed out by Geraldson (1962), Kelbert et al.,

(1966) Wolfenbarger (1967), Davis et al. (1970), Stephens (1973),

Locascio and Myers (1974).

The value of pruning and training tomatoes varies considerably

with different localities, seasons and cultivars. These practices are

intimately associated with economics of the crop so that no specific

recommendations can be made. Various methods of pruning and tying are

followed, but pruning to a single stem and tying the plant to a stake are

the most common. Ground culture is practiced when no artificial means of

support is provided for the tomato vine; usually the suckers are not

removed and the plant takes the appearance of a bush rather than vine.

Pruning the suckers is common in staked systems in which the main stem is

tied to a stake (Jones and Rose, 1928, Porte and Wilcox, 1963, Kelbert

et al., 1966).

Removal of 4 to 7 branches for determinate type plants has been

shown to increase fruit at the 3rd, 4th and 5th harvest (Burgis and

Levins, 1974); but the same authors, working with the determinate type

"Walter," showed that 3 prunings caused plants to produce the highest

total number of 13.61 kg cartons, followed by 0, 6 and 9 prunings.

Market value was at a maximum for 9 prunings. Other details about

advantages and disadvantages of pruning and training are given by

Kelbert et al. (1966).






11


Tomato Pests


Insects


Soil insects. The most common soil insect pests associated with

tomato crops are cutworms, Feltia subterranea (Fab.) and Agrotis spp.;

mole crickets, Scapteriscus spp.; lesser cornstalk borers, Elasmopalpus

lignosellus (Zeller). All of these insects can chew or cut the stems

of seedlings at ground level, causing them to fall over and die. They are

especially troublesome during the 2 3 weeks immediately after trans-

planting. Cutworms also feed on the leafy parts of the plants. Besides

direct damage, mole crickets also cause mechanical damage by burrowing in

the upper soil causing the soil and roots to dry out (Hayslip, 1943,

Stephens, 1973, Short and Driggers, 1973, Poe, 1976).

The control of the soil insect pests has been based on chemical

treatment recommendations (Johnson et al., 1974, Short and Driggers,

1973). Short and Driggers made recommendations for mole cricket control,

based on the behavior of the insects according with their life cycle.

Poe (1976) indicated that the number of mole crickets in field populations

could be estimated by the number of burrows and concluded that untreated

canals and/or untreated fields are sources of mole cricket reinfestations

for the treated lands.

Sucking insects. The most common sucking insects attacking

tomatoes are the green peach aphid, Myzus persicae (Sulzer), the potato

aphid, Macrosiphum euphorbiae (Thomas), and the green stinkbug, Nezara

viridula (L.). Aphids attack the young, tender leaves, suck out the

juices, and often serve as vectors of mosaic disease pathogens on

tomatoes. Stinkbugs damage fruit by sucking juices, causing them to

either fall or develop abnormally or with discolored areas. Damage






12


caused by stinkbugs are recognized by the presence of a round, white,

cloudy blotch, 1-10 mm diam. just below the surface of the fruit; some-

times the fruits are classified as culls (Stephens, 1973, Chalfant, 1973).

It is not usually necessary to make separate chemical applications

against aphids and stinkbugs, they frequently are controlled by insec-

ticides applied against leafminers or fruitworms (Johnson et al., 1974).

Shorey and Hall (1963) reported that aphids seldom occur in densities

which could directly impede plant growth, and it is doubtful whether

conventional insecticide treatments are of value in suppressing insect

borne birus diseases in tomatoes. Some cultural practices have been

explored to control aphids. Wolfenbarger (1967) showed that the incidence

of mosaic-virus was delayed by using aluminum and plastic as mulch in

tomatoes. He stated that aluminum surfaces repel aphids.

Chalfant (1973), using a scale of 1-5 for classification, showed

that potato aphids caused damage of 4.7 on vines in untreated plots; he

used a scale of 1 = no damage, 5 = severe leaf burn and distortion.

In plots treated 6 times with chemicals the least damage was 1.8; no

mention was made on infestation densities. Also, the same author dem-

onstrated that Nezara viridula (L.) caused damage in fruits of 17.4,

20.0 and 22% (1969, 1970, 1971 respectively) in untreated plots whereas,

in treated plots, the least damage was 7.8% with 4 applications (1969);

0% with 6 applications (1970); and 0% with 6 applications (1971).

Again, no mention was made of densities.

Foliage insects. Leafminers, Liriomyza sativae Blanchard and

loopers, Trichoplusia ni (Hub.), are common species that attack tomatoes.

Wolfenbarger (1947) reported that both larvae and adults of leafminers

caused damage on tomato plants. Leafminers have been the subject

of many studies including biological and chemical controls






13

based on prevention (Wolfenbarger, 1954, 1958, Hills and Taylor, 1951,

Wene, 1953, 1955, Baranowski, 1959a, 1959b, Shorey and Hall, 1963,

Harding, 1971, Poe 1974b). Throughout these studies it has been shown

that the use of some insecticides would cause disruptions of leafminer

populations, either by killing parasites or by inducing resistance (see

Poe, 1974b, Musgrave et al., 1975, and Oatman and Kennedy, 1976). The

potential of other alternatives of control, such as plant resistance,

was explored by Webb et al. (1971). The effect of stake and mulch cul-

tures of tomatoes on the response of leafminer and its parasites was

studied by Price and Poe (1976). They found that stake and mulch cul-

tures have a positive influence on leafminers and their parasites, so

tomatoes, grown under these methods must receive greater care in pest

management programs.

Little refined work has been done on the effect of leafminer

populations on tomato yield. Wolfenbarger and Wolfenbarger (1966)

stated that the threshold for leafminer was at an average of 1 or more

mines per each leaflet of a leaf. However, Levins et al. (1975)

concluded that there was no evidence that leafminers directly affect

tomato yields, and emphasized the importance of recording yield quality

and quantity as well as population responses in pesticide trials.

Fruit and Foliage insects. Some insects which feed on foliage

are also included in the category of fruit feeders, notably tobacco

hornworm, Manduca sexta (Joh.), Southern armyworm, Spodoptera eridania

(Cramer), beet armyworm S. exigua (Hub.), tomato pinworm, Keiferia

lycopersicella (Walsh.), and the properly named tomato fruitworm,

Heliothis zea (Boddie). There is much information about this insect

pest complex and in many cases publications refer to two or more species,

however, past and present studies indicate that armyworms and fruitworms





14


are the most serious pests of stake tomatoes in Florida (Poe, 1974b).

Madden (1945) studied the biology and some aspects of population

dynamics of tobacco hornworms. He concluded that parasites, predators

and diseases, keep the pest population within certain limits, but none

are of much value in "direct control." Middlekauff et al. (1963) found

that infestations of hornworm resulted in damage to 12% of fruit in

untreated plots, but Barrett.et al. (1971) reported damage of 24% on green

fruits and 9% on ripe fruits. Oatman and Planter (1971) demonstrated

that releases of Trichogramma pretiosum Riley, increased by 10% the number

of hornworm eggs parasitized. Creighton et al. (1971) found in untreated

plots 270 hornworm larvae per 100 tomato plants, but no relation of this

number to damage was indicated.

Armyworms cause damage similar to that of fruitworms, but damage

is usually more superficial and consists of shallow holes, less than

inch deep on the sides of the fruit (Wilcox et al., 1956). No infor-

mation about the relation of larval densities to damage was shown.

Shorey and Hall (1963) reported reduction of armyworm populations from

142 to 12 larvae per 32 plants with 7 applications of chemicals.

Middlekauff et al. (1963) indicated that armyworms caused damage to 11%

of the fruits. Creighton et al. (1971) reported that in untreated plots,

armyworms caused damage to 88% of the fruits.

The pinworm, Keiferia lycopersicella (Walsingham), was first

reported in the U.S. from Imperial County, California, in 1923, and since

1936 has been reported causing losses in late canning and market tomatoes

(Elmore, 1943). This insect reached epidemic proportion in some local-

ities in Florida, due to various factors (Wolfenbarger and Poe, 1973,

Poe et al., 1975). Dissemination of the insect occurs by transporting

young seedlings (Batiste et al., Swank, 1973, Poe et al., 1975).






15

Larvae feed in tomato leaves (leaf folder), young fruit, old fruit and

stems; boring damage on fruit occurs during the latter half of the larval

life cycle. A large proportion of the larvae enter the fruit core, beneath

the calyx resulting in pin holes (Elmore, 1943, Wolfenbarger and Poe,

1973). Oatman (1970) stated that high temperatures and low or no rain-

fall provide favorable conditions for a rapid increase of pinworm.

Middlekauff et al. (1963) found that uncontrolled infestations of

pinworms caused damage to 12% of the fruits, but Harding (1971) reported

damage at 20%. Wolfenbarger and Poe (1973) showed a general relation-

ship in which use of chemicals reduced leaf injury and worm holes result-

ing in increased fruit yield, but after 9 chemical applications no re-

lation was evident between leaf infestation and fruit damage, although

they found infestations as high as 7.25 pinworms per plant in the check

plot and as low as 0.5 in the treated plot. Also, Poe and Everett (1974)

found no correlation among leaf mines, presence of larvae and fruit loss;

however, they reported losses of 4.4% in number and 5.5% in weight in

the untreated check, meanwhile, the best treatment had losses of 0.5%

and 0.6% respectively.

Poe et al. (1975) stated that integration of horticultural prac-

tices, choice of variety and chemical selectivity with early biological

controls offer the greatest potential for pinworm management. They

found that Apanteles dignus Musebeck and A. scutellaris Musebeck caused

50-60% mortality during late part of the season. Indeterminate

varieties showed higher pinworm populations than determinate varieties.

Insect growth regulators such as ZR-619 and ZR-777, used against pin-

worms, caused great mortality to the two parasites (Poe, 1974a).

Wolfenbarger et al. (1975) showed that leaf damage by larvae of

the tomato pinworm reduced yield of tomatoes. The authors developed a






16


sequential sampling plan for damage of the pinworm larvae, based on two

spatial distributions; the Normal and the Poisson distributions.

The fruitworm Heliothis zea (Boddie) has been considered one of

the most destructive insects on tomato (Oatman and Planter, 1971), not

only because of its capacity for damage but also because it is difficult

to control. The main damage is caused when larvae feed on fruits,

although leaves and stems are also attacked. Wilcox et al. (1956) stated

that half of the damage caused by fruitworms occurred in the first

quarter of fruit harvest, but Middlekauff et al. (1963) reported that,

in untreated plots, the number of injured fruits increased as the season

advanced and averaged 27.7% when the second harvest was underway.

Wilcox et al. (1956) suggested that one larvae per plant could

damage between 2.2% and 8.6% of the fruits, and that 7 larvae per plant

an average of 28.3%. They emphasized that 1 egg per 100 leaves could

result in about 3% fruit damage; a heavy infestation was that able to

cause 20% of fruit damage. Shorey and Hall (1963) reported that an

average of 9.45% of the tomatoes in untreated plots were injured by the

tomato fruitworm; Middlekauff et al. (1963) found a higher average of

17.6%.

Oatman and Planter (1971) showed that biological control of fruit-

worms was effective on early plantings of processing tomatoes, using

twice-weekly releases of Trichogramma pretiosum Riley at ca. 465,000/

acre. Parasitization of tomato fruitworm eggs was 5 times higher in the

release field than in the control. Larvae caused 2.1% and 7.2% of fruit

damage in the released and control fields, respectively.

There is no uniformity with respect to damage caused by fruitworm

larvae. The former references and the following illustrate such dis-

crepancies. Harding (1971) reported 16.50%; Creighton et al. (1971),





17


61.0%; Creighton et al. (1973), 64.2% to 71.5%; Fery and Cuthbert (1974a),

13.1% to 17.3%; Creighton and McFadden (1976), 90.4% of fruit damaged in

untreated plots. These data indicate that fruitworm is able to cause

severe damage, but the damage grade could be different depending on the

population density, area, crop season and stage of the crop. In some

cases, yield quality and not quantity is affected (Shorey and Hall, 1963,

Poe, 1974b). Tomatoes demand greater protection during the fruit set and

maturation phases, and chemicals applied in these periods reduced the

damage caused by insects (Poe, 1974b).

The use of resistant varieties to reduce damage of insects in

tomato has not been completely explored. A tomato cultivar with even

partial resistance to the fruitworm would be of considerable value in

a pest management program (Fery and Cuthbert, 1974a). Canerday et al.

(1969) found a significant inverse relationship between number of fruit

per variety and percentage of damaged fruit. Fery and Cuthbert (1975)

reported the presence of a factor highly inhibitory to tomato fruitworm

larvae, in leaves of Lycopersicon hirsutum Humb. and Bonpl. and L.

Hirsutum f. Glabratum C.H. Mull.




Diseases

Tomatoes are subject to a number of diseases caused by fungi,

bacteria, viruses and certain unfavorable soil or climatic conditions.

Seedling diseases are not usually serious because fungicide treatment

of seeds or fumigation of seedbeds or beds in the field reduce some of

soil-borne fungal populations.

However, there are soil-borne pathogens which are serious problems,

especially those causing wilt diseases; Fusarium oxysporum (Schlecht.) f.






18


lycopersici (Sacc.) Snyder and Hansen; Pseudomonas solanacearum E.F.

Smith and Verticillium albo-atrum Reinke and Berth.

Cultural practices together with chemicals have been used in con-

trolling soil-borne pathogens. Geraldson et al. (1965) reported that

plastic mulch increased the effectiveness of fungicides in controlling

systemic pathogens such as Fusarium and bacterial wilt; this is not the

case with Verticillium wilt, because field fumigations do not eradicate

the pathogen, but only delay the attack (Jones and Crill, 1975).

However, marketable fruit was increased by paper or polyethylene mulch,

because of improved wilt control and a better distribution of nutrients

and moisture (Jones et al., 1972). Jones and Woltz (1972) found that

the incidence of Verticillium increased and that of Fusarium wilt

decreased by raising the soil pH, from 5.0 to 7.0 or 7.5. On the other

hand, Woltz and Jones (1973) indicated that a combination of high nitrate,

low ammonium, and lime affected Fusarium wilt adversely.

Jones and Crill (1973) made a summary of the yield reduction

caused by Verticillium wilt. They reported conflicting views and

suggested that different races could cause different damage depending

on the variety. This disease can cause reduction of yield on tomatoes

as high as 68% on susceptible varieties, 39% on tolerant and none or

slight on resistant varieties.

There are other diseases recognized as pest problems on tomatoes

which require chemical control but information about their reduction of

yields is scarse. Such diseases include: late blight, Phytophthora

infestans (Mart.) dBy; Phytophthora parasitica; early blight, Alternaria

solani (Ell. and Mart.) Jones and Crout; Rhizoctonia solani Kuehn;

bacterial spot, Xanthomonas vesicatoria (Doige) Dows; soft-rot, Erwinia

caratovora (L. R. Jones) Holland.






19


The most prevalent virus problems in tomato are tobacco mosaic

virus (TMV), potato virus (PVY), tobacco etch virus (TEV) and to a lesser

extent, pseudo-curly top disease. Apnids can be vectors of PVY and TEV,

and Micrutalis malleifera Fowler is vector of the pseudo-curly top disease.

Loss from these diseases have never exceeded 5% (Simons, 1962). Early

inoculation 8 days after field planting, with TMV, reduced yields of

tomatoes significantly more than late inoculation, at 10 weeks after field

planting (Weber, 1960, Crill et al., (1970).




Nematodes


There are few data relating losses to nematodes on tomatoes.

Some of the more common nematodes which damage tomato roots are root-knot,

Meloidogyne spp., reniform, Rotylenchulus sp., sting nematodes, Belonolaimus

spp., stubby-root, Trichodorus spp., root-lesion, Pratylenchus spp., stunt,

Tylenchorhynchus spp. Root-knot nematodes can be extremely severe pests

on tomatoes on lands that have been cultivated for a long time. Many of

these nematodes may cause drastic yield reductions unless effectively

controlled. Good cultural practices and/or chemicals prior to lnanting,

reduce damage caused by nematodes (Kelbert et al., 1966, Johnson et al.,

1974). Although yield reduction of tomatoes has been associated with

root-knot nematode infection by Hayslip et al. (1952), and Walter and

Kelsheimer (1949), publications by Overman and Jones (1968), and Overman

(1975). indicated no relation between nematode populations and fruit

yield. Potation with pangolagrass pastures has been recommended to reduce

or eliminate certain problems caused by soil-borne diseases and nematodes

in old lands (Hayslip et al., 1964).






20


Weeds


Weeds compete with tomato plants for water, nutrients and sun-

light. Weeds also harbor insects, plant pathogens and nematodes. The

effects of weed presence, and influence on tomato yields, depends on

several factors such as type of soil, moisture, season, rotation practiced,

and of course, are different from one area to another. Some of the most

common weeds found in Florida are crabgrass, Digitaria sanguinalis (L.)

Scop.; goosegrass, Eleusine indica Gaertn.; bermudagrass, Cynodon dactylon

(L.) Pers. Others are annual sedge, Cyperus spp.; Aclipta eclipta, Eclipta

alba L. (Hass.); common pigweed, Amaranthus spp.; purslane, Portulaca spp.;

nightshade, Solanum spp. (Burgis, 1973a, 1973b).

Burgis (1973a) indicated that data for 2 seasons demonstrated

that there was reduction in both number and size of tomato fruits when no

herbicide was used, but no data were given to support this assertion.

He showed that several herbicides gave excellent control of weeds on row

middles and in-the-row in mulched tomatoes, however, neither total yield

nor fruit weight were increased significantly when compared with the check-

hand weeded one, although the last practice gave 0.0% of weed control.

Johnson et al. (1975) reported that a single application of selected

pesticide combinations to control multiple pests (fungi, weeds and

nematodes) on tomato transplants would increase yield by 41%.















MATERIALS AND METHODS



Experiment 1 1975


The objective of this experiment was to determine, quantitatively,

crop losses caused by different destructive factors in tomatoes.

Tomato plants used in this experiment were obtained as seedlings in trays

of individual-cells from the University of Florida Agricultural Research

and Education Center at Bradenton, Florida.

Experiment 1 was done in a field of the Archer Road Entomology

Laboratory in Gainesville, Florida. Plants were placed 17 inches apart

in bedded rows on 40 inch centers. Fertilizer, 8:8:8, at the rate of

800 pounds per acre was banded on each shoulder of beds prior to trans-

planting. "Walter" tomato seedlings were set by hand on March 18, 1975,

and three weeks later, 700 pounds per acre of fertilizer was placed be-

tween rows in all the plots. Overhead sprinklers provided moisture for the

crop when necessary. Weed control was done by hand regularly and the plants

were pruned and staked 6 weeks after transplanting.

The experimental unit consisted of plots 29 feet long and 20

feet wide. The plot was divided into five rows 40 inches apart, planted

with 100 seedlings, 20 per row. Each row was considered as one repli-

cation for recording data, and for analysis. Three plots were used during

the experiment (Figure 1).

To determine the range of different mortality factors on the

yield, tomatoes were grown under 3 different strategies; a Management



21





















---29 feet---


17" 140"

20 feet







Check Management Commercial







Figure 1. The experimental design and field block arrangement for tomato crop life table
study during 1975 and 1976.






23


approach, a Conventional Commercial approach and an untreated Check.

Although, in some cases, techniques to control individual pests were

available, only chemical control of insects was applied in this

experiment.

Sampling techniques consisted of counting and recording the

number of insects of each species per plot each week. Sampling began on

April 1 and during the first 4 weeks all the plants per plot were checked.

After April 29, due to the increased size of the plants, every other plant

in each plot was checked.

In spite of the volume of information available on tomatoes, no

reliable data on economic thresholds for the major pests were found for

using in the Management strategy. Based on the sampling data, a level of

infestation was calculated each week and when this level was higher than

a previously established economic threshold, an insecticide application

was made, otherwise no action was taken. Levels of infestation (per 100

plants) considered as possible cause of yield reduction were as followed:

1) prior to fruiting, 15 larvae of Heliothis spp. and/or 10 larvae of

Spodoptera spp.; 2) after fruiting, 6 larvae of Heliothis spp., and

15 larvae of K. lycopersicella (Walsh.).

To protect the plants against foliar diseases, 2 pounds per acre

of 80% WP Manzate 200R was applied at weekly intervals. When deemed

necessary, dimethoate 2.67 EC (1 pt per acre) plus methomyl (2 pounds ai

per acre) were sprayed. Fungicide and insecticides were mixed, before

application. Application was made with a hand sprayer and at volume of

50 gallons per acre during the first three weeks and 100 gallons per

acre during the remainder of growth period. Insects were counted from

April 1 to May 29.





24


The second strategy resembled conventional commercial practices

of tomato production. The same fungicide and insecticides used as needed

in the pest management block were applied to this block, but on a weekly

schedule. The first application was made on March 25, the final one on

May 29. Sampling for insects present on the plot were initiated on April 1

and continued until May 29. The sampling procedure was unchanged from

that given for management strategy.

The third strategy, or no control (Check) was chosen to determine

the effect on tomatoes of the different factors. The plot in which this

strategy operated received weekly application of the fungicide. The rate

and application method was equal to those used for the other two plots.

Applications of fungicide were between March 25 and May 29. The sampling

procedure was similar to the other two plots.

In an effort to determine the sequence of key factors acting

during the time plants were in the field, five crop developmental stages

were selected. Transplant period, extending from the time that seedlings

were set in the field to first bloom was observed, a period of ca. 2 weeks

and during which the root system became established. The Bloom period

extended from the time of the first bloom until 50% of the plants had

blooms, an interval lasting ca. 2 weeks. Fruit Set period extended from

the time when 50% of the plants had bloomed until ca. 50% of fruit had

set, a period of vegetative growth and fruit production lasting ca. three

weeks. The fourth stage or Maturation period extended from the end of

the third period until the appearance of mature green tomatoes, a period

lasting ca. four weeks. The final stage was Harvest, a period lasting

ca. four to six weeks.

The crop developmental stages were used as a means to conveniently

determine when certain mortality or cull factors have a significant impact






25


on the number of plants, or on quality and quantity of fruit. These

intervals do not necessarily represent physiological stages of develop-

ment.

A complete inventory of plants per plot was made at the beginning

of each of the crop development stages. Mortality records of the plants

were taken every two or 3 days throughout the first three periods, the

time during which the greatest potential for loss of plants occurred.

All of the plants in each plot were examined on each recording date and

when severe damage occurred, the plant was considered as dead.

The data taken at each sampling interval was number of aphids

per plant; number of new leafminer mines per plant; number of pinworm

larvae per plant; number of larvae and eggs of armyworms, number of

Heliothis and hornworms per plant.

Unripe fruit injured by caterpillar feeding or disease was

recorded at regular intervals beginning shortly after Fruit Set, the

remaining fruit was allowed to vine-ripen. Then, the ripe fruits were

harvested and sorted as marketable or unmarketable if damage by insects,

diseases or other factors was evident. The first harvest was made on

June 3 and the last on June 28.

The format and symbols used for crop life tables in this experi-

ment are the same as those used by Harcourt (1970). The first column,

x, gives the sampling period, viz, the crop development stage; the

second, Ix, the number of plants living at the beginning of the period;

the third, dxF, the mortality factor acting during the respective period;

the fourth, dx, the number of plants lost within a specific period; and

the fifth, 100rx, is the percentage of mortality based on the initial

plant population.






26


The format and symbols used for fruit life tables in this

experiment are patterned after those used by Harcourt (19/0), but the

values were estimated differently. The fruit population per plot was

determined by the number of fruits harvested, thus the number of fruits

for the transplant period is equal to the total number harvested plus

the fruit lost or damaged throughout the different growth periods. The

tabulation shows the impact of each cull factor in relation to those

remaining fruits at specific time intervals during the season. This

procedure was used by Hall, 1974.

For the fruit life table, the first column, x, gives the sampling

period; the second, lx, the number of fruits present at the beginning of

the period; the third, dxF, the cull factor acting during the respective

period; the fourth, dx, the number of fruits lost or cull fruits caused

by the key factor, and the fifth, 100rx, is the percentage of fruit lost

based on those remaining fruits for the respective period.

The number of fruits harvested per plot was used to estimate

production per acre, based on 6,400 plants. Potential dollars revenue

and loss per acre were calculated having in mind a sale price of $0.18

per pound of tomato, in accordance with Brooke (1976).




Experiment 2 1976


The second experiment was planted on March 12, 1976 at the IFAS

Horticultural Unit, at Gainesville, Florida. The objective, materials

and methods and technologies used throughout Experiment 1 were followed

in Experiment 2. Sprays were started on March 18, and suspended

on May 21. The first harvest was made on May 22 and the last on July 7.





27


Estimates of the fluctuation of soil arthropod populations were

taken during the second experiment. A pit-fall trap was placed within

each row per plot at ca. weekly intervals and an overnight catch was

recorded. The arthropods collected were sorted and sent to the State

Department of Agriculture, Division of Plant Industry, Bureau of Entomology

for identification. The collections were started on April 6 and ended on

May 30.
















RESULTS


Mortality and cull factors are noted separately, in the appro-

priate respective life table, as they were recorded in each growth period.

The economic impact due to each factor is based on the percentage of damage

and on 6,400 plants per acre as well as on the unit prices given by

Brooke (1976).



Experiment 1 1975


Management Plot


Life table. An analysis of tomato injury, using the life table

format, is shown in Table 1. At the start of the Transplant period,

there were 100 plants with a potential production of 1,225 tomatoes per

plot. During that period, three mortality factors were present. Mole

crickets caused 2.0% plant mortality which corresponds to a potential

fruit loss of 25 tomatoes per plot, cutworms destroyed 3.0% of the plants

which accounted for 37 potential fruits, and finally damp-off destroyed

1.0% of the plants corresponding to 12 fruits per plot. The total damage

caused by these three factors, at the end of the Transplant period, was

6.0% of plants and 74 potential fruits per plot.

At the beginning of the Bloom period, there were 94 surviving

plants with a potential production of 1,151 fruits per plot. Damp-off

was the only cause of mortality in this growth interval. A loss of 2.0%

of plants (Table 1) was recorded, equivalent to 25 lost fruits per plot.



28






29


Ninety-two plants began the Fruit Set period with 1,126 potential

fruits per plot. No mortality factors were recorded during this third

period.

During the Maturation period three major factors affected fruits,

here referred to as cull factors because the damage was restricted to

the fruits. Heliothis spp. and Spodoptera spp. were the species of

fruitworms recorded during the season on the Management plot; the total

numbers of these species are given on Tables 18 and 19. Sorting of

fruit damaged by each species was not possible so damage done by both

species together accounted for the damage to fruit caused by insects.

The damage figures in the Maturation period were recorded at the time

of harvest. The potential number of fruit present at the start of this

period was 1,126 per plot (Table 1). Insects were the major agent

responsible for fruit damage and resulted in 11.5% loss in numbers per

plot.

Three diseases caused loss on the fruits. Symptoms were identi-

fied as soft rot (bacteria), blossom-end rot,and cracking (nutritional

and physiological disorders) (Tables 1 and 13). Together these diseases

accounted for 2.3% of fruit lost, that is, 26 fruits per plot.

Mechanical damage was the second factor of importance in Maturation

period. The damage occurred mainly because of hand weed control prac-

tices and the staking and tying operations. The damage reached 6.1%

of the fruits per plot, equivalent to 70 tomatoes (Tables 1 and 13).

Insects and diseases, together, during the Transplant and Bloom

periods reduced the plant population by 8.0%, corresponding to 99 fruits.

All cull factors injured 20.0% of the potential fruits. At the moment

of harvest 28.2% of the potential yield was recorded as fruits lost due

to all the destructive factors throughout the four growth periods








1
Table 1. Crop life table for tomatoes, variety "Walter," Gainesville, Fla. 1975 (Management plot I)


PLANTS FRUITS

Growth Number Mortality Number Percent of Number Cull Number Percent of
Period living factor lost mortality per plot factor lost per loss
per plot per plot per plot
(x) (Ix) (dxF) (dx) (100 rx) (lx) (dxF) (dx) (100 rx)

Transplant 100 Mole crickets 2 2.00 1,225c* Mole crickets 25 2.04

Cutworms 3 3.00 Cutworms 37 3.02

Damp-off* 1 1.00 Damp-off* 12 0.97

Sub-total 6 6.00 Sub-total 74 6.04

Bloom 94 Damp-off* 2 2.00 1,151 Damp-off*. 25 2.17

Fruit Set 92 None 0 0.00 1,126 None 0 0.00

Maturation 92 None 0 0.00 1,126 Insects 130 11.54

Diseases 26 2.31

Mechanical 70 6.18

Sub-total 226 20.03

Harvest 92 900

Yield 92 Total 8 8.00 900 324 28.24

*Caused by Rhizocotonia spp.

**Fruits per plot based on actual number harvested.









Table 2. Estimated dollar loss by major mortality factor on tomatoes, 1975 (Management plot I).

PLANTS FRUITS

Growth Potential Hazard Loss Potential Hazard Loss
period $/acre $/acre $/acre $/acre

Transplant 2,661.12 Mole crickets 53.22 2,661.12 Mole crickets 54.28

Cutworms 79.83 Cutworms 80.36

Damp-off 26.61 Damp-off 25.81

Sub-total 159.66 Sub-total 160.45

Bloom 2,501.24 Damp-off 53.22 2,500.67 Damp-off 54.26

Fruit Set 2,448.24 None 0.00 2,446.41 None 0.00

Maturation 2,448.24 None 0.00 2,446.41 Insects 282.31

Diseases 56.51

Mechanical 151.18

Sub-total 490.00

Harvest 2,448.24 1,956.41

Yield 2,448.24 Total 212.88 1,956.41 704.71

Cost values based on estimates of Brooke, 1976, and Table 1.






32


(Tables 1 and 13). Only 900 tomatoes were classified as marketable of

a total of 1,225 potential per plot.


Economic analysis. The impact of the major mortality factors con-

verted into monetary values per acre, is shown in Table 2. The potential

fruit production value per acre would be $2,661 of revenue.

During the Transplant period, mole crickets caused a reduction of

potential revenue of about $54 per acre, cutworms of $80,and damp-off

of $25. The total estimated dollar loss was ca. $160 per acre. Damp-off

was the only mortality factor in the Bloom period. The economic impact

was estimated as equivalent to $54 per acre (Table 2).

A potential revenue of $2,446 per acre was calculated for the Fruit

Set and Maturation periods. The economic loss due to Heliothis spp.

and Spodoptera spp. was $282 per acre, to diseases $56,and finally to

mechanical factors $151, during Maturation period (Table 2).

Taken together, insects caused losses of $417, diseases $136,and

mechanical, $151. After subtracting losses due to damage by insects,

diseases,and to mechanical causes an income of $1,956 per acre was

obtained. This amount represents ca. 74% of the estimated potential of

$2,661 (Table 2).

The cost/benefit ratio per acre is shown in Table 15. Insecti-

cides were the only variable involved, so I will only mention the cost

of this variable. The retail price for insecticides for 5 applications

was $75, thus, the net return $1,881 per acre, corresponds to 71% of

the potential revene.

Insect populations. The fluctuations of insect populations

were recorded weekly and the results are shown in Tables 16 to 19.

No infestations of pinworm were observed. Methomyl plus dimethoate were






33

applied 5 times after April 29 against aphids, Heliothis spp. and

Spodoptera spp. The two latter species of pests were persistent and the

schedule of application did not eliminate the infestations or completely

prevent damage. Armyworms (Spodoptera spp.) were present only on the

Management plot (Table 19).

The average number of aphids per plot was significantly higher in

the Management than in the Check plot during the 5 weeks before in-

secticide application, but the average number present after insecticide

applications was reduced significantly and total elimination occurred

May 27 (Table 16). The average number of leafminers (Liriomyza sativae

Blanchard) was significantly less than in the Check plot during the first

three weeks of sampling but was not different from the Commercial plot

average (Table 17).

Heliothis spp. eggs were detected from April 1 and throughout the

sampling period (Table 18). Despite the applications of insecticides

after April 29, larval populations were present until the time sprays

were suspended on May 29. The maximum number of eggs, per 100 plants,

4 was found on April 10 and the maximum number of larvae, per 100 plants,

6 was found on May 21 and 29 (Table 18). Spodoptera spp. larvae were

observed on April 29, localized in rows 1 and 3, at such density that

the decision was made to treat with insecticide. The application gave

80% control of the pest, the remaining 20% of the larvae caused damage

on fruits recorded later during harvest.






34


Commercial Plot


Life table. The crop life table format used for analyzing tomato

injury is shown in Table 3. The Transplant period was initiated with

100 plants with a potential of 1,037 fruits per plot. This potential

yield represents the total number of tomatoes harvested plus the number

lost due to various factors. Three major factors of mortality acted on

the tomato plants during the Transplant period. Mole crickets,and damp-

off each caused 2.0% mortality, and cutworms 4.0%. These percentages

represent a loss of 21, 21 and 41 tomatoes respectively per plot.

The total damage due to these three factors, at the end of Transplant

period, was 8% of the plants, and 83 potential fruits per plot.

The Bloom period began with 92 surviving plants with a potential

of 954 tomatoes per plot. Damp-off reduced the plants by 1.0% and this

percentage corresponds to a loss of 10 fruits per plot. During the Fruit

Set period, an additional loss of 1.0% was caused by damp-off.

Ninety surviving plants began the Maturation period with 933

potential fruits per plot. Three major cull factors occurred in this

period on fruits especially and were recorded in the harvest data.

Heliothis spp, larvae were the only agents responsible for fruit damage

and caused 9.0% loss, that is, 84 fruits per plot. Soft rot, blossom-

end rot,and cracking, accounted for 1.6% cull fruits per plot, while,

mechanical damage was recorded as 6.4% of the fruits, equivalent to 60

tomatoes per plot.

During the Transplant and Bloom periods, together, insects and

diseases reduced the plant population by 10.0%. This percentage

represents a loss of 104 potential fruits per plot. One hundred and

fifty-nine tomatoes were recorded as cull fruits. Taken together,









Table 3. Crop life table for tomatoes, variety "Walter," Gainesville, Fla. 1975 (Commercial plot II)

PLANTS FRUITS

Growth Number Mortality Number Percent of Number Cull Number Percent of
period living factor lost mortality per plot factor lost per loss
per plot per plot plot
(x) (lx) (dxF) (dx) (100 rx) (Ix) (dxF) (dx) (100 rx)

Transplant 100 Mole crickets 2 2.00 1,037** Mole crickets 21 2.02

Cutworms 4 4.00 Cutworms 41 3.95

Damp-off* 2 2.00 Damp-off* 21 2.02

Sub-total 8 8.00 Sub-total 83 7.99

Bloom 92 Damp-off* 1 1.00 954 Damp-off* 10 1.05

Fruit Set 91 Damp-off* 1 1.00 944 Damp-off* 10 1.06

Maturation 90 None 0 0.00 934 Insects 84 9.00

Diseases 15 1.60

Mechanical 60 6.43

Sub-total 159 17.03

Harvest 90 775

Yield 90 Total 10 10.00 775 262 27.13

* Caused by Rhizoctonia spp.

** Fruits per plot based on actual number harvested.






36


destructive factors accounted for 262 fruits lost per plot. From a

potential production of 1,037 fruits, 775 were classified as marketable

per plot at harvest (Tables 3 and 13).

Economic analysis. The economic impact of the major mortality or

cull factors in the Commercial plot, in a per acre basis, is shown in

Table 4. The estimated potential revenue would be $1,993, this value was

reduced by $40, $78, and $40 by mole crickets, cutworms,and damp-off

during the Transplant period. Together, these losses amounted to $159

per acre.

Table 4 shows that during Bloom and Fruit Set period the economic

impact due to damp-off was $38 per acre.

The revenue from the fruits remaining at the beginning of the

Maturation period was estimated at $1,795 per acre. From data in

Table 4, it is evident that economic losses caused by insects was greater

than that caused by pathogens or mechanical injury even when taken together.

Insect losses amounted to $163, whereas losses to diseases and mechanical

injury were $28 and $116 per acre respectively (Table 4).

In the Commerical plot, during the four growth periods, insects

reduced the potential revenue by $282, disease injury by $107,and

mechanical damage by $116. After subtracting those values an income of

$1,487 per acre was obtained. This amount represents ca. 75% of the cal-

culated potential of $1,993 per acre (Table 4).

Cost/benefit analyses are shown in Table 15. Insecticide costs

for 10 applications per acre were calculated at $150; thus, the net return

of $1,337 per acre, represents 67% of the estimated potential revenue.









Table 4. Estimated dollar loss by major mortality factors on tomatoes, 1975 (Commercial plot II).1

PLANTS FRUITS

Growth Potential Hazard Loss Potential Hazard Loss
period $/acre $/acre $/acre S/acre

Transplant 1,993.00 Mole crickets 39.86 1,993.00 Mole crickets 40.26

Cutworms 79.72 Cutworms 78.72

Damp-off 39.86 Damp-off 40.26

Sub-total 159.44 Sub-total 159.24

Bloom 1,833.59 Damp-off 19.93 1,833.79 Damp-off 19.25

Fruit Set 1,813.66 Damp-off 19.93 1,814.54 Damp-off 19.23

Maturation 1,793.73 None 0.00 1,795.31 Insects 163.36

Diseases 28.72

Mechanical 115.97

Sub-total 308.05
Harvest 1,793.73 1,487.26

Yield 1,793.73 Total 199.19 1.487.26 505.77

Cost values based on estimates of Brooke, 1976, and Table 3.






38

Insect populations. The numbers recorded for the insect popula-

tions are shown in Tables 16 to 19. Sampling was done weekly. Insecti-

cide applications of methomyl plus dimethoate were started March 25 and

continued weekly until May 29. Table 16 provides data which indicates

that insecticides failed to provide 100% aphid control. However, the

average number of aphids per plot was significantly lower in the

Commercial plot than in the Management and Check plots during 6 of the

9 weeks of sampling (Table 16).

The average number of leafminers (Liriomyza sativae Blanchard) was

significantly lower in the Commercial plot than in the Check plot only

on 3 of the 9 dates of sampling. Data in Table 17 indicates that average

numbers of this insect were not significantly different for the

Commercial and Management plots.

Heliothis spp. eggs were detected for the first time on April 10

and reached a maximum number of 4 per 100 plants on April 22 (Table 18).

The first larvae was observed on April 22 and the maximum number (4 per

100 plants) were observed on May 29. This pattern of larval fluctuation

and abundance suggests that insecticides did not eliminate the population.

It is possible that the time of applications was inappropriate since older

and larger larvae are more difficult to kill.



Check Plot


Life table. Crop life table data for the Check plot are shown

in Table 5. One hundred plants were present at the start of the Trans-

plant period. Based on the number of fruits harvested, these plants

represent 717 tomatoes per plot. Again,three major mortality factors

were recorded during this growth period. Mole crickets killed 3.0% of

the plants present, and consequently reduced the potential production by









Table 5. Crop life table for tomatoes, variety "Walter," Gainesville, Fla. 1975 (Check plot III)

PLANTS FRUITS
Growth Number Mortality Number Percent of Number Cull Number Percent of
period living factor lost mortality per plot factor lost loss
per plot per plot per plot
(x) (lx) (dxF) (dx) (100 rx) (lx) (dxF) (dx) (100 rx)

Transplant 100 Mole crickets 3 3.00 717** Mole crickets 22 3.07

Cutworms 2 2.00 Cutworms 14 1.95

Damp-off* 3 3.00 Damp-off* 22 3.07

Sub-total 8 8.00 Sub-total 58 8.09

Bloom 92 Damp-off* 1 1.00 659 Damp-off* 7 1.06

Fruit Set 91 Damp-off* 1 1.00 652 Damp-off* 7 1.07

Maturation 90 None 0 0.00 645 Insects 129 20.00

Diseases 33 5.11

Mechanical 32 4.96

Sub-total 194 30.07

Harvest 90 451

Yield 90 Total 10 10.00 451 266 40.29

* Caused by Rhizoctonia spp.

** Fruits per plot based on actual number harvested.







40

22 fruits. Cutworms, also, killed 2.0% of the plant population, and.

damp-off was responsible for an additional loss of 3.0% per plot.

These three key factors accounted for 8.0% of plants lost and a reduction

of 58 tomatoes of the potential yield per plot.

The Bloom period was initiated with 92 plants with 659 potential

tomatoes per plot. Damp-off resulted in an additional 1.0% of plant loss

equivalent to 7 fruits per plot (Table 5).

Damp-off as mortality factor was recorded during the Fruit Set

period, so, at the ending of this period there were 90 surviving plants

with a potential production of 645 fruits per plot (Table 5).

Three fruit cull factors were recorded for the Maturation period.

The damage caused by these factors was observed at harvest. Insects

injured 20.0% of the tomatoes, diseases 5.1% and mechanical factors, 5.0%.

Together, these percentages are equivalent to 194 fruits lost per plot

(Table 5).

At the moment of harvest, 40.2% of the potential yield was recorded

as fruits lost (266) due to all the destructive factors throughout the

four growth periods (Tables 5 and 13). From a potential yield of 717

fruits per plot, only 451 were classified as marketable.

Economic analysis. The potential revenue per acre was estimated

as $1,382 (Table 6). During the Transplant period, mole crickets reduced

the potential revenue by $42, cutworms $27, and damp-off $42 per acre.

The economic impact of the three mortality factors was $111 per acre.

An additional reduction of $27 was recorded in the Bloom and Fruit Set

periods (Table 6).

For the Maturation period, a potential revenue of $1,243 per acre

was calculated. Heliothis spp. reduced the potential revenue by $249









Table 6. Estimated dollar loss by major mortality factors on tomatoes, 1975 (Check plot III).1




Growth Potential Hazard Loss Potential Hazard Loss
period $/acre $/acre $/acre $/acre

Transplant 1,382.00 Mole crickets 41.46 1,382.00 Mole crickets 42.43

Cutworms 27.64 Cutworm 26.95

Damp-off 41.46 Damp-off 42.43

Sub-total 110.56 Sub-total 111.81

Bloom 1,271.44 Damp-off 13.86 1,270.19 Damp-off 13.46

Fruit Set 1,257.58 Damp-off 13.71 1,256.73 Damp-off 13.45

Maturation 1,243.87 None 0.00 1,243.28 Insects 248.65

Diseases 63.53

Mechanical 61.66

Sub-total 373.84
Harvest 1,243.87 869.44

Yield 1,243.87 Total 138.20 869.44 512.56

Cost values based on estimates of Brooke, 1976, and Table 5.






42


per acre, diseases by $63 and mechanical factors by $62 during the

Maturation period (Table 6).

Throughout the four growth periods in the Check plot, insects

were responsible for a reduction of revenue of $318, diseases $133,and

mechanical $62 per acre. After subtracting economic losses due to the

key factors, the estimated revenue was $869 per acre. This value is ca.

63% of the potential of $1,382 (Table 6).

The relative cost/benefit is shown in Table 15. The net return

per acre was estimated at $869. No cost per insecticide was subtracted

since the Check plot received no insecticide applications.

Insect populations. The insect population fluctuations based on

weekly sampling are shown in Tables 16 to 19. Average numbers of Myzus

persicae Sulzer were significantly higher than those in the Commercial

plot on 7 of the 9 sampling dates, and higher than those in the Manage-

ment plot during 8 of the 9 sampling weeks (Table 16). Average numbers

of Liriomyza sativae Blanchard were significantly higher than those in

the Commercial plot only during 3 sampling periods, and significantly

higher than those in the Management plot, 4 times (Table 17).

Heliothis zea Boddie eggs were detected the first time on April 10.

A peak of major infestation, 6 larvae per 100 plants, was recorded on

May 29 (Table 18).




Experiment 2 1976


Management Plot


Life table. Crop life table data for the Management plot are

shown in Table 7. Mole crickets were the most important factor causing






43


mortality during the Transplant period. This pest destroyed 8.0% of the

100 plants present and reduced by 120 tomatoes the potential of 1,498

per plot. Following in importance were cutworms which killed 3.0% of

the plants, a value corresponding to 45 tomatoes. Damp-off affected 1.0%

of the plants equivalent to 15 potential tomatoes per plot. At the end

of the Transplant period, the total damage caused by these three factors

was 12.0% of the plants and 180 fruits per plot (Table 7).

No mortality factors were oboer-.ed during the Bloom and Fruit Set

periods, thus the number of plants remained at 88 with a potential pro-

duction of 1,318 tomatoes per acre.

For the Maturation period the cull factors were insects, diseases,

and mechanical damage. All these factors were recorded at the time of

harvest. Three species of insects, Heliothis spp., pinworm (Keiferia

lycopersicella) and hornworm, were responsible for 139 tomatoes or 10.5%

loss of the potential production. Symptoms of three diseases were

identified, soft-rot (bacteria), blossom-end rot,and cracking, which

reduced yield by 8.8%, approximately 116 fruits per plot. Mechanical

damage resulted in a loss of 8.3%, 110 fruits per plot (Tables 7 and

14).

As a consequence of all destructive factors throughout the four

growth periods, 544 tomatoes were lost. Of a potential of 1,498 fruits

per plot, 953 were classified as marketable (Tables 7 and 14).

Economic analysis. The economic impact of the major mortality

and cull factors, on a per acre basis, is shown in Table 8. The po-

tential revenue was estimated in $2,995. This amount was reduced by

$239 due to mole crickets, $90 by cutworms,and $30 by damp-off, during

the Transplant period. No additional losses were recorded for the

Bloom and Fruit Set periods.









Table 7. Crop life table for tomatoes, variety "Walter," Gainesville, Fla. 1976 (Management plot I)

PLANTS FRUITS
Growth Number Mortality Number Percent of Number Cull Number Percent of
period living factor lost mortality per plot factor lost loss
per plot per plot per plot
(x) (lx) (dxF) (dx) (100 rx) (lx) (dxF) (dx) (100 rx)

Transplant 100 Mole crickets 8 8.00 1,498** Mole crickets 120 8.01

Cutworms 3 3.00 Cutworms 45 3.00

Damp-off* 1 1.00 Damp-off* 15 1.00

Sub-total 12 12.00 Sub-total 180 12.01

Bloom 88 None 0 0.00 1,318 None 0 0.00

Fruit Set 88 None 0 0.00 1,318 None 0 0.00

Maturation 88 None 0 0.00 1,318 Insects 139 10.55

Diseases 116 8.80

Mechanical 110 8.33

Sub-total 365 27.68

Harvest 88 953

Yield 88 Total 12 12.00 953 544 39.64

* Caused by Rhizoctonia spp.

** Fruits per plot based on actual number harvested.









Table 8. Estimated dollar loss by major mortality factors on tomatoes, 1976 (Management plot I).1

PLANTS FRUITS

Growth Potential Hazard Loss Potential Hazard Loss
period $/acre $/acre $/acre $/acre

Transplant 2,995.20 Mole crickets 239.61 2,995.20 Mole crickets 239.61

Cutworms 89.86 Cutworms 89.86

Damp-off 29.95 Damp-off 29.95

Sub-total 359.42 Sub-total 359.42

Bloom 2,635.78 None 0.00 2,635.78 None 0.00

Fruit Set 2,635.78 None 0.00 2,635.78 None 0.00

Maturation 2,635.78 None 0.00 2,635.78 Insects 278.07

Diseases 231.94

Mechanical 219.56

Sub-total 729.57
Harvest 2,635.78 1,906.21

Yield 2,635.78 Total 359.42 1,906.21 1,088.99

Cost values based on estimates of Brooke, 1976, and Table 7.





46



Heliothis zea Boddie, Keiferia lycopersicella (Walsh.) and tobacco

hornworm caused an economic damage of $278 per acre, during the Maturation

period. Diseases reduced income by $232 and mechanical losses were esti-

mated as equivalent to $219. The three factors were responsible for a

reduction of $729 per acre (Table 8).

In general, insects, diseases,and mechanical destructive factors

had an economic impact of $1,089 per acre. After subtracting the esti-

mated loss from the potential revenue, an income of $1,906 was obtained.

This value represents 64% of the potential estimated per acre (Table 8).

Since no insecticide was applied to the Management plot, the net return

per acre was estimated at $1,906.

Insect populations. The number of insect populations recorded

weekly are shown in Tables 20 to 24. Aphids were present during the

season, but average number was not significantly different from those of

the Commercial or Check plots. Maximum infestation (5,240 per 100 plants)

was reached on May 7,and a minimum (25 per 100 plants) on March 25. A

pathogenic infection of the aphid population was observed and from a

sample taken on May 25 a species of Fusarium was isolated. High numbers

of aphids were observed only on one outside row throughout the sampling

interval (Table 20). The average number of leafminers was significantly

higher than that of the Check plot on April 2, but was significantly

lower than both the Commercial and Check plots, on April 23 (Table 21).

Heliothis spp. eggs were detected on March 25 and reached a peak

on April 30 (8 eggs per 100 plants). Larvae reached a peak on May 7 and

two more on May 14 and 21 with an infestation of 4 larvae per 100 plants

each time (Table 22). The maximum number of pinworms was detected on

April 20 and May 7. On each sampling date, 4 larvae per 100 plants were

found (Table 23). The hornworms occurred during the last two weeks of






47



sampling. Four larvae per 100 plants were recorded on May 14 and 10

larvae on May 21.

The arthropods collected by the pit-fall trap are shown in

Table 25. The total number captured was 165 individuals (Table 26).

Ninety-six (58%) of the individuals were identified as beneficial

(predators, parasites, pollinators), 35 (21%) as pests (or pathogen

vectors) and 34 (21%) as scavengers (especially members of Nitidulidae

family).




Commercial Plot


Life table. The typical analysis for the Commercial plot is

shown in Table 9. From the 100 plants at the start of the experiment

production was estimated at 1,600 tomatoes per plot. The Transplant

period had three major mortality factors. Mole crickets and damp-off

each affected 4.0% of the plants present and thus 64 fruits. Cutworms

caused half as much damage, 2.0% of plants and 32 tomatoes per plot.

Together these pests accounted for a loss of 10.0% of the plants and a

reduction of 160 potential fruits.

In the Bloom period, 90 plants were surviving with a potential

production of 1,440 tomatoes per plot. Damp-off reduced by 2.0% of the

remaining plants, equivalent to 32 additional fruits.

No mortality factors were observed during the Fruit Set period,

thus, 88 plants were present with 1,408 potential fruits (Table 9).

The Maturation period was characterized by the action of three

cull factors namely insects, diseases,and mechanical injury, which were

again recorded at the harvest time. Heliothis spp., pinworm and horn-









Table 9. Crop life table for tomatoes, variety "Walter," Gainesville, Fla. 1976 (Commercial plot II)

PLANTS FRUITS

Growth Number Mortaligy Number Percent of Number Cull Number Percent of
period living factor lost mortality per plot factor lost loss
per plot per plot per plot
(x) (lx) (dxF) (dx) (100 rx) (Ix) (dxF) (dx) (100 rx)

Transplant 100 Mole crickets 4 4.00 1,600** Mole crickets 64 4.00

Cutworms 2 2.00 Cutworms 32 2.00

Damp-off* 4 4.00 Damp-off* 64 4.00

Sub-total 10 10.00 Sub-total 160 10.00

Bloom 90 Damp-off* 2 2.00 1,440 Damp-off* 32 2.22

Fruit Set 88 None 0 0.00 1,408 None 0 0.00

Maturation 88 None 0 0.00 1,408 Insects 101 7.20

Diseases 75 5.30

Mechanical 104 7.39

Sub-total 280 19.44

Harvest 88 1,128

Yield 88 Total 12 12.00 1,128 472 31.66

*Caused by Rhizoctonia spp.

**Fruits per plot based on actual number harvested.






49


worm were responsible for damage to 101 fruits, approximately 7.2% of

the potential yield. Soft-rot, blossom end-rot, and cracking accounted

for 75 fruits equivalent to ca, 5.3% of the estimated potential yield.

Mechanical damage was of the order of 104 tomatoes or ca, 7.4% of the

harvest (Tables 9 and 14). Only 1,128 tomatoes were classified as

marketable of a total of 1,600.

Economic analysis. The impact of the major mortality and cull

factors, translated to monetary values per acre, is shown in Table 10.

An amount of $3,283 was estimated as potential income per acre.

Mole crickets, cutworms, and damp-off reduced the potential

income by $328 during the Transplant period. Damp-off had an additional

economic impact equivalent to $65 in the Bloom period. For the Fruit

Set period the estimated potential income was $2,889. The economica

losses due to Heliothis spp., pinworm, and hornworm was $208 per acre,

$153 due to diseases and $213 caused by mechanical damage. After

subtracting these values, an income of $2,314 per acre was estimated.

This amount represents ca. 70% of the calculated potential of $3,283

(Table 10).

Values for the cost/benefit analysis are shown in Table 15.

Insecticide costs for 10 applications per acre were estimated at $150,

thus, the net return of $2,164 represents 66% of the potential revenue

per acre.

Insect populations. Insect infestations are shown in Tables 20

to 24. Methomyl plus dimethoate sprays were applied on a weekly

schedule starting on March 18 until May 21. Aphid average was not

significantly different from those of the Commercial or Check plots.

On April 16, the maximum infestation was recorded (130 aphids per 100

plants), and the minimum (0 per plant) was observed on April 2 (Table 20).









Table 10. Estimated dollar loss by major mortality factors on tomatoes, 1976 (Commercial plot II).1


PLANTS FRUITS

Growth Potential Hazard Loss Potential Hazard Loss
period $/acre $/acre $/acre $/acre

Transplant 3,283.20 Mole crickets 131.33 3,283.20 Mole crickets 131.33

Cutworms 65.66 Cutworms 65.66

Damp-off 131.33 Damp-off 131.33

Sub-total 328.32 Sub-total 328.32

Bloom 2,954.88 Damp-off 65.60 2,954.88 Damp-off 65.60

Fruit Set 2,889.28 None 0.00 2,889.28 None 0.00

Maturation 2,889.28 None 0.00 2,889.28 Insects 208.02

Diseases 153.13

Mechanical 213.52

Sub-total 574.67

Harvest 2,889.28 2,314.61

Yield 2,889.28 Total 393.29 2,314.61 968.59

Cost values based on estimates of Brooke, 1976, and Table 9.






51



These data indicate that insecticides failed to provide 100% aphid

control. No significant differences occurred between the three treat-

ment strategies, when the leafminer average was considered (Table 21).

Heliothis spp. eggs were detected for the first time on March 25.

The maximum number of eggs found was 10 per 100 plants on May 7 and the

highest number of larvae (4 per 100 plants) occurred on May 7 and 14

(Table 22). Pinworms were present from April 16 to May 14. Two larvae

per 100 plants were found each time (Table 23). Hornworms appeared on

the last two weeks and large larvae were observed consuming green fruits.

Four larvae per 100 plants were recorded on March 21 (Table 24).

Tables 25 and 26 show the number of arthropods collected by the

pit-fall trap in the Commercial plot. During the nine sampling weeks,

116 individuals were captured. Of this amount, 56 (48%) were considered

as beneficial, 32 (28%) as pest and 28 (24%) as scavengers. The bene-

ficial arthropods were predators, parasites and pollinators, most of

the pests were pathogen vectors insects and most of the scavengers were

members of the Nitidulidae family,



Check Plot


Life table. The life table shown in Table 11 indicates that

there were three major mortality factors during the Transplant period.

Loss of plants due to mole crickets, cutworms and damp-off were 3.0%,

8.0% and 1.0% respectively, which is equivalent to 26, 71 and 9 fruits

lost per plot. These values are lower than those in the Management

and Commercial plots because they are based on the yield obtained from

50 plants. The mortality factors mentioned before, reduced potential

fruits by 106 per plot.









Table 11. Crop life table for tomatoes, variety "Walter," Gainesville, Fla. 1976 (Check plot III).

PLANTS FRUITS

Growth Number Mortality Number Percent of Number Cull Number Percent of
period living factor lost mortality per plot factor lost loss
per plot per plot per plot
(x) (lx) (dxF) (dx) (100 rx) (Ix) (dxF) (dx) (100 rx)

Transplant 100 Mole crickets 3 3.00 882** Mole crickets 26 3.00

Cutworms 8 8.00 Cutworms 71 8.00

Damp-off* 1 1.00 Damp-off* 9 1.00

Sub-total 12 12.00 Sub-total 106 12.00

Bloom 88 None 0 0.00 776 None 0 0.00

Fruit Set 88 Unknown 38 38.00 776 Unknown 335 43.00

Maturation 50 None 0 0.00 441 Insects 105 23.22

Diseases 93 21.08

Mechanical 10 2.26

Sub-total 208 47.14

Harvest 50 233

Yield 50 Total 50 50.00 233 649 102.14

* Caused by Rhizoctonia spp.

** Fruits per plot based on actual number harvested.







53


No plants in the Bloom period suffered mortality, thus 88 plants

were present and the potential yield was 776 tomatoes.

During the Fruit Set period a severe disorder was noted, which

caused a reduction of 38 plants per plot. Symptoms included stunting,

loss of vigor and no growth, The plants were consequently considered

as dead since they never recovered and although some were alive at the

harvest time, no fruits were produced (Table 11).

The Maturation period presented 50 plants with a potential pro-

duction of 441 tomatoes per plot. Table 11 shows that the same three

cull factors were operative, namely insects, diseases and mechanical

injury. Heliothis spp., pinworms and hornworms caused loss of 105

tomatoes. Soft rot, blossom-end rot and cracking reduced the potential

yield by an additional 93 tomatoes. Mechanical damage accounted for

only 10 fruits per plot (Table 14).

Economic analysis. The potential fruit production value per acre

was estimated at $922 (Table 12). This value was reduced $28 by mole

crickets, $74 by cutworms and $9 by damp-off, during the Transplant

period. Together, these values accounted for $111 per acre.

A potential revenue of $811 was estimated for the Bloom period.

No mortality factor was recorded in this period.

The severe disorder visible during the Fruit Set period, caused

a reduction estimated at $349 per acre. The economic loss due to

Heliothis spp., pinworms and hornworms was $110 per acre, $97 due to

diseases and $14 to mechanical damage, during the Maturation period

(Table 12). After subtracting all losses due to damage by destructive

factors, an income of $240 was obtained. This value represents ca.

26% of the estimated potential of $922 per acre.









1
Table 12. Estimated dollar loss by major mortality factors on tomatoes, 1976 (Check plot III).

PLANTS FRUITS

Growth Potential Hazard Loss Potential Hazard Loss
period S/acre S/acre $/acre $/acre


Transplant 921.60 Mole crickets 27.65 922.00 Mole crickets 28.00

Cutworms 73.73 Cutworms 74.00

Damp-off 9.22 Damp-off 9.00

Sub-total 110.60 Sub-total 111.00

Bloom 811.00 None 0.00 811.00 None 0.00

Fruit Set 811.00 Unknown 349.00 811.00 Unknown 349.00

Maturation 462.00 None 0.00 462.00 Insects 110.00

Diseases 97.40

Mechanical 14.00

Sub-total 221.40

Harvest 462.00 239.60

Yield 462.00 Total 459.60 239.60 681.40


Cost values based on estimates of Brooke, 1976, and Table 11.






55



Insect populations. The fluctuation in insect populations was

recorded weekly and the results are shown in Tables 20 to 24. No sig-

nificant differences occurred between the three treatment strategies

when aphid averages were considered. On April 16 the highest infesta-

tion of aphids was recorded (28 per 20 plants), By May 14 the aphid

population had disappeared from the plot (Table 20). Leafminers showed

a pattern similar to that previously mentioned. The maximum number

(140 per 100 plants) was found on April 23. During the last two weeks

no new leafminers were observed (Table 21).

Heliothis spp. eggs were observed on March 25 and larvae (3 per

100 plants) on April 16. Eight larvae per 100 plants were observed on

April 30, was the maximum number (Table 22). Pinworms appeared early

on March 25, The population showed a relative stability during the

season, but on April 30 and May 7, a level of 6 larvae per 100 plants

was found (Table 23). Hornworms were observed on the last two sampling

dates, May 14 and May 21 (Table 24). It is possible that the infesta-

tions would not be a hazard for a vigorously growing plant, but for

a mature plant the damage occurs to the fruits, and therefore is in-

tolerable.

The numbers of arthropods captured by the pit-fall trap are

shown in Tables 25 and 26. From a total of 141 individuals collected,

92 (65%) were identified as beneficial, 23 (17%) as pests and the

remainder 26 (18%) as scavengers.










Table 13. Total fruits harvested and damaged by insects (I), diseases (D) and mechanical (M) per
plot, 1975.


Management Commercial Check

Harvested Damaged Harvested Damaged Harvested Damaged

Date I* D** M I* D** M I* D** M


6-3-75 136 12 3 12 59 4 1 2 56 10 2 0

6-7-75 135 26 2 5 79 8 1 8 72 20 3 3

6-14-75 373 41 10 23 223 11 5 9 148 10 10 5

6-18-75 102 10 4 5 186 20 2 18 84 35 7 15

6-23-75 207 27 5 15 161 21 1 8 135 20 7 4

6-28-75 173 14 2 10 226 20 5 15 150 12 5 5


Total 1126 130 26 70 934 84 15 60 645 129 33 32


* Insects were Heliothis spp. and Spodoptera spp.
** Diseases were soft-rot (bacteria), blossom-end rot and cracking (nutritional and physiological
disorders).





CY










Table 14. Total fruits harvested and damaged by insects (I), diseases (D) and mechanical (M) per
plot, 1976.

Management Commercial Check

Harvested Damaged Harvested Damaged Harvested Damaged

Date I* D** M I* D** M I* D** M

5-22-76 34 3 2 2 60 3 1 1 20 2 3 1

5-29-76 85 11 9 13 91 8 7 10 40 7 7 1

6-4-76 67 8 6 7 85 6 2 2 27 9 7 1

6-9-76 91 12 9 5 105 8 3 4 40 16 10 2

6-15-76 257 30 15 20 268 21 12 25 74 12 16 1

6-22-76 392 35 30 37 360 25 20 30 121 32 23 2

6-30-76 271 25 34 20 294 20 22 17 70 13 17 1

7-6-76 121 15 11 6 145 10 9 15 49 14 9 6


Total 1318 139 116 110 1408 101 75 104 441 105 93 10

* Insects were Heliothis spp., Keiferia lycopersicella (Walsh.) and Manduca sexta (Joh.).
** Disease were soft-rot (bacteria), blossom-end rot and cracking (nutritional and physiological
disorders).







58




Table 15. Costs and benefits of alternative control methods for
tomatoes.


Number Cost $
Method of (Insecticides Benefit Net return
applications only) S/acre $/acre


1975

Management 5 75 1,956.41 1,881.41

Commercial 10 150 1,481.26 1,337.26

Check 0 0 869.44 869.44


1976

Management 0 0 1,906.21 1,906.21

Commercial 10 150 2,314.61 2,164.61

Check 0 0 239.60 239.60


Average

Management 2.5 37.50 1,931.31 1,893.81

Commercial 10 150 1,900.93 1,750.93

Check 0 0 554.52 554.52


IBased on Tables 2, 4, 6, 8, 10 and 12.










Table 16. Total numbers of Myzus persicae (Sulzer) per plot, 1975.

Date of sample

Plot Row Apr 1 Apr 10 Apr 16 Apr 22 Apr 29 May 6 May 13 May 21 May 27


Management 1 18 6 34 63 100 10 20 0 0
2 81 47 60 201 430 4 16 4 0
3 68 23 98 294 385 6 14 8 0
4 20 34 65 179 425 0 0 6 0
5 39 32 45 80 330 4 8 2 0

Average 42.5al 28.4a 60.4a 163.5a 334.0a 4.8a 11.6a 4.0a 0


Commercial 1 10 4 13 7 10 12 4 10 0
2 4 7 11 11 8 6 2 4 0
3 7 23 12 17 15 10 6 8 0
4 3 5 19 19 7 4 10 0 0
5 3 14 17 12 9 0 4 2 0

Average 5.4b 10.6b 14.4b 13.2b 9.8b 4.4a 5.2b 4.8a 0


Check 1 13 1 26 15 85 266 44 144 10
2 18 11 25 26 10 54 230 102 0
3 13 9 58 24 50 190 102 308 62
4 22 21 61 42 120 252 540 330 52
5 21 22 72 37 100 227 474 262 102

Average 17.4c 12.8b 48.4c 28.8c 73.Oc 189.8b 278.Oc 209.2b 43.2


1 uJ
Column averages followed by the same letter are not significantly different at 5% Duncan's multiple
range test.










Table 17. Total mines of Liriomyza sativae Blanchard per plot, 1975.


Date of checking

Plot Row Apr 1 Apr 10 Apr 16 Apr 22 Apr 27 May 6 May 13 May 21 May 29


Management 1 1 5 10 3 1 0 0 4 4
2 6 10 12 1 0 0 0 0 0
3 3 5 9 2 4 2 2 2 2
4 1 2 7 0 1 4 0 0 0
5 3 7 4 2 0 0 4 0 0

Average 2.8al 5.8a 5.8a 0.6a 1.2a 1.2a 1.2a 1.2a 1.2a


Commercial 1 2 3 4 0 1 0 0 0 0
2 5 8 1 2 1 4 2 0 2
3 6 0 0 3 2 6 0 0 0
4 14 5 3 0 0 2 4 0 4
5 4 4 2 1 1 0 0 0 0

Average 6.2b 4.0a 4.0a 1.2a l.Oa 2.4a 1.2a Oa 0.4a


Check 1 4 6 10 2 2 16 4 0 2
2 3 8 13 1 1 20 6 10 2
3 8 14 8 0 1 14 0 0 0
4 10 15 16 3 2 30 10 6 2
5 6 12 12 0 3 20 2 4 2

Average 6.2b 11.8b 11.8b 1.2a 1.8a 20.0b 4.4a 4.0a 1.6a

1
Column averages followed by the same letter are not significantly different at 5% Duncan's multiple
range test.










Table 18. Total larvae (1) and eggs (2) of Heliothis spp. per plot, 19751


Date of sample

Apr 1 Apr 10 Apr 16 Apr 22 Apr 29 May 6 May 13 May 21 May 29
Plot Row 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2

Management 1 0 0 0 3 0 0 1 1 1 0 0 0 0 1 2 0 2 0
2 0 0 0 1 0 0 0 2 0 0 1 0 0 0 2 0 0 0
3 0 1 0 0 1 0 0 0 1 0 0 2 0 1 2 0 2 0
4 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0
5 0 0 0 0 0 0 0 0 1 0 0 0 0 2 0 0 2 0



Commercial 1 0 0 0 0 0 0 0 2 0. 0 0 0 0 0 0 0 2 0
2 0 0 0 1 0 0 0 0 0 0 0 2 2 0 2 0 0 0
3 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0
4 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 2 0
5 0 0 0 0 0 1 1 2 1 0 0 0 0 0 0 0 0 0



Check 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 2 0
2 0 0 0 0 0 0 0 0 1 0 0 0 0 1 2 0 1 0
3 0 0 0 0 1 0 0 0 0 0 4 2 0 0 1 0 1 0
4 0 0 0 1 0 0 0 0 1 0 0 0 4 0 2 0 2 0
5 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0

1Dc
Data not significantly different.










Table 19. Total larvae of Spodoptera spp. per plot, 19751


Date of sample

Plot Row Apr 1 Apr 10 Apr 16 Apr 22 Apr 29 May 6 May 13 May 21 May 29

Management 1 0 0 0 0 20 4 2 0 0
2 0 0 0 0 0 0 0 0 0
3 0 0 0 0 35 4 2 0 0
4 0 0 0 0 0 2 2 0 0
5 0 0 0 0 0 0 0 0 0



Commercial 1 0 0 0 0 0 0 0 0 0
2 0 0 0 0 0 0 0 0 0
3 0 0 0 0 0 0 0 0 0
4 0 0 0 0 0 0 0 0 0
5 0 0 0 0 0 0 0 0 0



Check 1 0 0 0 0 0 0 0 0 0
2 0 0 0 0 0 0 0 0 0
3 0 0 0 0 0 0 0 0 0
4 0 0 0 0 0 0 0 0 0
5 0 0 0 0 0 0 0 0 0


Data not significantly different.




IC.3









Table 20. Total numbers of Myzus persicae (Sulzer) per plot, 1976.

Date of sample
Season
Plot Row Mar 25 Apr 2 Apr 9 Apr 16 Apr 23 Apr 30 May 7 May 14 May 21 eason
Total

Management 1 26 39 62 142 1384 1427 3840 1500 204 8624
2 0 0 9 105 146 275 710 1480 200 2925
3 0 0 0 27 81 226 560 720 300 1914
4 0 0 0 3 2 10 106 40 180 341
5 0 0 1 18 2 4 26 10 4 65

Average 5.2al 7.8a 14.4a 59.0a 323.0a 388.4a 1048.0a 750 178 2773.8a


Commercial 1 2 0 3 36 15 4 2 4 2 68
2 0 0 12 9 2 0 2 0 0 25
3 1 0 1 43 1 2 0 0 0 48
4 0 0 0 33 8 0 0 0 0 41
5 0 0 0 8 7 2 0 0 0 17

Average 0.6a Oa 3.2a 26a 6.6a 1.6a 0.8a 0.8 0.4 39.8a


Check 1 0 6 15 52 30 4 12 0 0 119
2 0 3 5 14 5 2 8 0 0 37
3 0 1 6 32 10 0 2 0 0 51
4 0 1 8 30 12 2 0 0 0 53
5 0 0 4 12 5 0 2 0 0 23

Average O.Oa 2.2a 7.6a 28a 12.4a 1.6a 5.8a 0 0 56.6a


Column averages followed by the same letter are not significantly different at 5%,Duncan's multiple
range test.









Table 21. Total mines of Liriomyza sativae Blanchard per plot, 1976.

Date of sample
Season
Plot Row Mar 25 Apr 2 Apr 7 Apr 16 Apr 23 Apr 30 May 7 May 14 May 21 Total
Total

Management 1 1 15 2 2 11 24 8 0 0 63
2 0 7 16 1 10 32 0 0 0 66
3 0 3 5 1 14 16 0 0 0 39
4 0 0 2 3 6 2 0 0 0 13
5 0 10 14 10 5 4 0 0 0 43

Average 0.2a1 7.0a 7.8a 3.4a 8.2a 15.6a 1.3 0 0 44.8a


Commercial 1 0 12 2 1 15 14 0 8 0 52
2 0 0 1 5 7 6 0 10 0 29
3 3 1 5 0 11 0 0 2 0 22
4 0 0 0 0 8 2 0 2 0 12
5 0 4 2 2 4 2 0 2 0 16

Average 0.6a 3.4ab 2.0a 1.6a 11.2ba 4.8a 0 4.8 0 26.2a


Check 1 9 1 1 1 20 4 0 0 0 36
2 0 0 3 1 8 4 0 0 0 16
3 0 1 0 3 16 6 0 0 0 26
4 0 0 0 1 16 10 2 0 0 29
5 2 1 1 3 16 15 0 0 0 38

Average 2.2a 0.6b 1.0a 1.8a 15.2b 5.8a 0.4 0 0 29.0a


1 ON
Column averages followed by the same letter are not significantly different at 5%,Duncan's multiple
range test.









1
Table 22. Total larvae (1) and eggs (2) of Heliothis spp. per plot, 1976.

Date of sample

Mar 25 Apr 2 Apr 9 Apr 16 Apr 23 Apr 30 May 7 May 14 May 21
Plot Row 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2

Management 1 0 1 1 0 1 0 0 0 0 0 0 2 2 2 2 0 0 0
2 0 0 0 0 0 0 1 1 0 1 2 4 0 2 0 0 2 6
3 0 0 0 0 0 0 0 0 1 0 0 2 2 0 2 0 2 0
4 0 0 0 0 0 0 1 0 0 2 2 0 0 0 0 0 0 0
5 0 0 0 0 0 0 1 1 1 0 0 0 0 2 0 0 0 0



Commercial 1 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0
2 0 0 0 0 0 0 1 0 0 2 0 0 2 6 2 0 0 0
3 0 1 0 0 0 0 0 0 1 2 0 0 0 4 2 0 0 0
4 0 0 0 0 0 0 0 1 0 0 2 2 0 0 0 0 2 0
5 0 0 0 0 0 0 0 0 0 0 0 2 2 0 0 0 0 2



Check 1 0 1 0 0 0 0 2 0 0 1 2 0 2 2 0 2 0 4
2 0 0 0 0 0 1 0 0 0 1 2 0 0 0 2 0 0 2
3 0 0 0 1 0 0 0 1 1 0 2 0 2 2 0 4 2 0
4 0 0 0 0 0 1 0 0 1 0 0 0 2 0 0 0 0 0
5 0 0 0 0 0 0 1 0 1 0 2 0 0 0 2 4 2 0

Data not significantly different.









Table 23. Total larvae of Keiferia lycopersicella (Walsh.) per plot, 19761


Date of sample

Plot Row Mar 25 Apr 2 Apr 9 Apr 16 Apr 23 Apr 30 May 7 May 14 May 21

Management 1 1 0 0 0 1 0 2 0 0
2 0 0 0 1 0 0 0 0 0
3 0 0 0 0 1 2 0 2 0
4 0 0 0 0 1 0 2 0 0
5 0 0 0 2 0 2 0 0 0



Commercial 1 0 0 0 0 0 2 0 2 0
2 0 0 0 0 1 0 0 0 0
3 0 0 0 1 0 0 2 0 0
4 0 0 0 0 1 0 0 0 0
5 0 0 0 1 0 0 0 0 0



Check 1 1 0 1 0 1 2 0 2 0
2 0 0 0 2 0 0 0 2 0
3 0 1 2 0 1 0 2 0 0
4 0 1 0 0 2 2 2 0 2
5 0 1 1 3 0 2 2 0 0

1
Data not significantly different.



a.
ON-









Table 24. Total larvae (1) and eggs (2) of Manduca sexta (Joh.) per plot, 19761


Date of

Mar 25 Apr 2 Apr 9 Apr 16 Apr 23 Apr 30 May 7 May 14 May 21
Plot Row 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2

Management 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0
2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0
3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0
4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 4 2 0
5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 4 2 0



Commercial 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 0
2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 0
4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0



Check 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 2 0
2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 2 0
4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0


Data not significantly different.










Table 25. Pit-fall trap captures of arthropods in Management (M), Commercial (C) and Check (Ch) plots
of tomatoes throughout nine sampling weeks. Gainesville, Fla., 1976.


Occurrence in plots
Family Scientific Common Frequency(%) Total No. Potential Comments
Frequency(%) Total No.
name name role
M C Ch M C Ch


Formicidae Conomyrma Ant 44 18 38 28 15 30 Predator Most individuals
flavopecta were observed early
M.R. Smith in crop season.

Miridae Spanogonicus Plant bug 20 20 20 18 17 15 Pest Most individuals
albofasciatus Predator were observed early
(Reuter) in crop season.

Lycosidae Lycosa spp. Wolf 6 9 0 4 4 0 Predator Most individuals
spider were observed in
mid season.

Lycosidae Pardosa spp. Wolf 18 11 29 15 6 25 Predator Captured throughout
spider crop season.

Lycosidae Arctosa spp. Wolf 4 0 7 2 0 3 Predator Captured early in
spider crop season.

Nitidulidae Carpophilus Sap 29 33 21 32 27 23 Scavengers Most individuals
mutilatus beetle were captured in mid
Erich crop season.

Tenebrionidae Blapstinus Darkling 4 0 2 2 0 1 Scavengers All individuals were
metallicus beetle collected early in
(Fab.) crop season.










Table 25. (Continued)


Occurrence in plots

Family Scientific Common Frequency(%) Total No. Potential Comments
name name role
M C Ch M C Ch


Carabidae Anisodactylus Ground 2 2 0 1 1 0 Predator All individuals were
spp. beetle collected early in crop
season.

Scarabaeidae Ataenius Scarab 9 7 2 4 5 1 Pest All individuals were
simulator beetle collected early in crop
Harold season.

Staphylinidae Philonthus Rove 9 2 2 4 1 1 Predator All individuals were
spp. beetle collected in mid crop
season.

Cicadellidae Graminella Blackfaced 2 4 0 1 2 0 Vector All individuals were
nigrifrons leafhopper virus collected in mid crop
(Forbes) season.

Elateridae Conoderus spp. Click 4 4 0 2 2 0 Pest Most individuals were
beetle collected late in crop
season.

Cicadellidae Exitianus Leafhopper 7 2 2 3 1 1 Vector Most individuals were
exitiosus virus collected late in crop
(Uhler) season.

Chalcididae Haltichella Chalcidid 2 0 0 1 0 0 Parasite Collected late in
spp. crop season.










Table 25. (Continued)


Occurrence in plots
Family Scientific Common Frequency(%) Total No. Potential Comments
Frequency(%) Total No.
name name role
M C Ch M C Ch


Lygaeidae Geocoris Bigeyed 2 0 2 1 0 Predator Both were collected
uliginosus bug late in crop season.
(Say)

Formicidae Pheidole Ant 20 2 13 11 1 6 Predator Most individuals were
morrisi collected throughout
Forel crop season.

Therevidae Steatoda spp. Stiletto 2 0 0 1 0 0 Predator Collected early in
fly crop season.

Gnaphosidae Gnaphosa spp. Gnaphosids 2 0 7 1 0 3 Predator Most individuals were
(spider) collected early in
crop season.

Sphecidae Alysson spp. Sphecid 2 0 0 1 0 0 Predator Collected early in
wasp crop season.

Halictidae Erylaeus spp. Halictid 16 7 18 14 3 15 Polinator Most individuals were
bee collected early in
crop season.

Therevidae Psilocephala Stiletto 7 2 0 3 1 0 Predator Collected throughout
spp. fly the crop season.

Formicidae Solenopsis Ant 16 29 7 7 17 4 Predator Collected throughout
geminata (Fabricius) the crop season.










Table 25. (Continued)


Occurrence in plots
Family Scientific Common F) T l No. Potential Comments
Frequency (%) Total No.
name name role
M C Ch M C Ch


Cicadellidae Carneocephala Leafhopper 2 0 2 1 0 1 Pest Both were collected
sagittifera early in crop season.
(Uhler)

Cicadellidae Polyamia Leafhopper 2 0 0 1 0 0 Pest Collected in mid
obtecta crop season.
(Osborn and
Ball)

Cicadellidae Aceratagallia Leafhopper 2 0 0 1 0 0 Pest Collected early in
sanguinolenta crop season.
(Provancher)

Chrysomelidae Epitrix spp. Leaf 2 4 2 1 2 1 Pest Collected throughout
beetle crop season.

Scarabaeidae Aphodius Scarab 2 0 0 1 0 0 Pest Collected late in
campestris beetle crop season.
Blatch.

Acrididae Grasshopper 2 0 0 1 0 0 Pest Collected early in
crop season.

Ichneumonidae Anamalon Ichneumon 2 0 0 1 0 0 Parasite Collected early in
spp. crop season.










Table 25. (Continued)


Occurrence in plots
Family Scientific Common Potential Comments
Frequency (%) Total No. role
name name role
M C Ch M C Ch


Mutillidae Pseudomethoca Velvet 2 0 0 1 0 0 Parasite Collected late in
spp. ant crop season.

Bibionidae Plecia Love bug 2 2 0 5 0 4 Scavenger Most individuals were
neartica collected in mid crop
Hardy season.

Braconidae Apanteles Braconid 0 4 0 0 2 0 Parasite Collected in first
spp. half of crop season.

Cantharidae Chauliognathus Soldier 0 2 0 0 1 0 Predator Collected late in
spp. beetle crop season.

Carabidae Anisodactylus Ground 0 2 0 0 1 0 Predator Collected early in
spp. beetle crop season.

Carabidae Pasimachus Ground 0 7 0 0 3 0 Predator Collected in the first
subsuleatus beetle half of crop season.
Say

Anthicidae Anthicus Antlike 0 2 0 0 1 0 Scavenger Collected late in
spp. flower crop season.
beetle

Inchneumonidae Exetastes Ichneumon 0 2 0 0 1 0 Parasite Collected early in
spp. crop season.










Table 25. (Continued)


Occurrence in plots
Family Scientific Common Frequl No. Potential Comments
Frequency(%)Total No.
name name role
M C Ch M C Ch


Scarabaeidae Onthophagus Scarab 0 2 0 0 1 0 Pest Collected early in crop
oklahomensis beetle season.
Brown

Tridactylidae Pygmy 0 2 0 0 1 0 Pest Collected in mid crop
molecricket season.

Cicadellidae Planicephalus Leafhopper 0 2 0 0 1 0 Pest Collected late in
spp. crop season.

Chloropidae Hippelates Frit fly 0 2 0 0 1 0 Adventicious Collected early in
spp. crop season.

Andrenidae Andrena Andrenid 0 2 0 0 1 0 Adventicious Collected early in
spp. bee crop season.

Chrysomelidae Aptica Leaf beetle 0 2 0 0 1 0 Pest Collected early in
spp. crop season.

Cicadellidae Macrosteles Aster 0 2 0 0 1 0 Vector Collected late in
fascifrons leafhopper aster crop season.
(Stol) yellows

Forficulidae Forficula spp. Earwigs 0 2 0 0 1 0 Predator Collected early in
crop season.










Table 25. (Continued)


Occurrence in plots
Family Scientific Common Potential Comments
Frequency(%)Total No.
name name role
M C Ch M C Ch


Tenebrionidae Crypticus Darkling 0 0 2 0 0 1 Scavenger Collected early in
obsoletus Say beetle crop season.

Aphididae Myzus Aphid 0 0 2 0 0 1 Pest Collected early in
persicae crop season.
(Sulzer)

Sphecidae Solierella Sphecid 0 0 2 0 0 1 Predator Collected early in
spp. wasp crop season.

Scollidae Scolia spp. Scollid 0 0 2 0 0 1 Parasite Collected late in
wasp crop season.

Sphecidae Oxybelus Sphecid 0 0 4 0 0 2 Predator Collected early in
spp. wasp crop season.

Meloidae Epicauta Blister 0 0 2 0 0 1 Pest Collected early in
spp. beetle crop season.

Buprestidae Acmaeodera Metallic 0 0 2 0 0 1 Pest Collected early in
spp. beetle crop season.

Gryllidae Cricket 0 0 2 0 0 1 Pest Collected late in
crop season.







75






Table 26. Total numbers of arthropods collected by pit-fall traps in
Management (M), Commercial (C), and Check (Ch) plots of
tomatoes during nine sampling weeks. Gainesville, Fla. 1976.


Pests* Beneficial** Scavengers***


M C Ch M C Ch M C Ch

35 32 23 96 56 92 34 28 26





*Include virus vector insects and some phytophagous.

**Most individuals were ants.

***Most individuals were of the Nitidulidae family.






76




Table 27. Estimated dollar loss by major mortality factors on tomatoes,
1975 (Management plot I).

FRUITS


Growth Potential* Loss
period $/acre Hazard % Loss** $/acre


Transplant 2,880 Mole crickets 2.0 57.60

Cutworms 3.0 86.40

Damp-off 1.0 28.80

Sub-total 6.0 172.80

Bloom 2,707.20 Damp-off 2.0 54.14

Fruit Set 2,653.06 None 0.0 0.00

Maturation 2,653.06 Insects 11.5 305.10

Diseases 2.3 61.02

Mechanical 6.2 164.48

Sub-total 20.0 530.60

Harvest 2,122.46


Yield 2,122.46 Total 757.54

1
Cost values based on estimates of Brooke, 1976.

*Based on the potential maximum yield over two seasons.

**Values based on percent of loss of respective treatment
strategy (Table 1).






77




Table 28. Estimated dollar loss by maj r mortality factors on tomatoes,
1975 (Commercial plot II).


FRUITS


Growth Potential* Loss
period $/acre Hazard % Loss** $/acre


Transplant 2,880 Mole crickets 2.0 57.60

Cutworms 4.0 115.20

Damp-off 2.0 57.60

Sub-total 8.0 230.40

Bloom 2,649.60 Damp-off 1.0 26.49

Fruit Set 2,623.11 Damp-off 1.0 26.23

Maturation 2,596.88 Insects 9.0 233.72

Diseases 1.6 41.55

Mechanical 6.5 168.79

Sub-total 17.1 444.06

Harvest 2,152.82


Yield 2,152.82 Total 727.18

Cost values based on estimates of Brooke, 1976.

* Based on the potential maximum yield over two seasons.

** Values based on percent of loss of respective treatment
strategy (Table 3).







78




Table 29. Estimated dollar loss by major mortality factors on tomatoes,
1975 (Check plot III)1


FRUITS

Growth Potential* Loss
period $/acre Hazard % Loss** $/acre


Transplant 2,880 Mole crickets 2.0 86.40

Cutworms 2.0 57.60

Damp-off 3.0 86.40

Sub-total 7.0 230.40

Bloom 2,649.60 Damp-off 1.0 26.50

Fruit Set 2,623.10 Damp-off 1.0 26.23

Maturation 2,596.87 Insects 20.0 519.37

Diseases 5.1 132.44

Mechanical 7.0 181.78

Sub-total 32.1 833.59

Harvest 1,763.28


Yield 1,763.28 Total 1,116.72
1
Cost values based on estimates of Brooke, 1976.

*Based on the best yield over two year seasons.

**Values based on percent of loss of respective treatment strategy
(Table 5).






79





Table 30. Estimated dollar loss by major mortality factors on tomatoes,
1976 (Management plot I).

FRUITS

Growth Potential* Loss
period $/acre Hazard % Loss** $/acre


Transplant 2,880 Mole crickets 8.0 230.40

Cutworms 3.0 86.40

Damp-off 1.0 28.80

Sub-total 12.0 345.60

Bloom 2,534.40 None 0.0 0.00

Fruit Set 2,534.40 None 0.0 0.00

Maturation 2,534.40 Insects 10.6 268.64

Diseases 8.8 223.02

Mechanical 8.3 210.35

Sub-total 27.7 702.01

Harvest 1,832.39


Yield 1,832.39 Total 1,047.61
1
Cost values based on estimates of Brooke, 1976.

* Based on the potential maximum yield over two seasons.

** Values based on percent of loss of respective treatment
strategy (Table 7).






80




Table 31. Estimated dollar loss by major mortality factors on tomatoes,
1976 (Commercial plot II).1


FRUITS

Growth Potential* Loss
period $/acre Hazard % Loss** $/acre


Transplant 2,880 Mole crickets 4.0 115.20

Cutworms 2.0 57.60

Damp-off 4.0 115.20

Sub-total 10.0 288.00

Bloom 2,592.00 Damp-off 2.0 51.84

Fruit Set 2,540.16 None 0.0 0.00

Maturation 2,540.16 Insects 7.2 182.89

Diseases 5.3 134.63

Mechanical 7.4 187.97

Sub-total 19.9 505.49

Harvest 2,034.67


Yield 2,034.67 Total 845.33

1
Cost values based on estimates of Brooke, 1976.

* Based on the potential maximum yield over two seasons.

** Values based on percent of loss of respective treatment
strategy (Table 9).






81





Table 32. Estimated dollar loss by major mortality factors on tomatoes,
1976 (Check plot III).


Growth Potential* Loss
period $/acre Hazard % Loss** $/acre


Transplant 2,880 Mole crickets 3.0 86.40

Cutworms 8.0 230.40

Damp-off 1.0 28.80

Sub-total 12.0 345.60

Bloom 2,534.40 None 0.0 0.00

Fruit Set 2,534.40 Unknown 38.0 963.07

Maturation 1,571.33 Insects 23.2 364.55

Diseases 21.0 314.26

Mechanical 2.2 34.57

Sub-total 46.4 713.38

Harvest 857.95


Yield 857. Total 2,022.05

1
Cost values based on estimates of Brooke, 1976.

* Based on the potential maximum yield over two seasons.

** Values based on percent of loss of respective treatment
strategy (Table 11).






82





Table 33. Costs and1benefits of alternative control methods for
tomatoes.

Number Costs $
of (Insecticides Benefit Net return
Strategy applications only) S/acre $/acre


1975

Management 5 75 2,122.46 2,047.46

Commercial 10 150 2,152.82 2,002.82

Check 0 0 1,763.28 1,763.28



1976

Management 0 0 1,832.39 1,832.39

Commercial 10 150 2,034.67 1,884.67

Check 0 0 857.95 857.95




Average

Management 2.5 37.5 1,977.45 1,939.95

Commercial 10 150 2,093.75 1,943.75

Check 0 0 1,310.61 1,310.61




1
Based on the potential maximum yield over two seasons (Tables 27 to 32).
















DISCUSSION



This study conducted over a two year period, is the first attempt

to utilize a modified crop life table to provide a suitable rationale

basis for management of tomato pests or for a multiple fruits bearing

crop. The results of this study indicate that life-table analyses are

suitable for tomatoes, permitting not only an insight into the time and

action of the different mortality and cull factors, but a direct cost

accounting of crop and fruit loss. The information provided by crop

life tables can be used to improve decisions and reduce uncertainty

present in some pest management programs.




Transplant Period


The life table format illustrates how early in the season pests

often ignored can be responsible for significant losses in potential

tomato yield. As soon as the plants are set in the field, mole crickets,

cutworms,and damp-off become serious hazards. Although only direct

effect is included in the table, other indirect effects are involved,

namely costs of new seedlings and labor of checking and replanting,

fertilizer and irrigation,and loss of revenue from the empty space.

A rational basis for the cultural practices of fumigation and mulching

could be obtained through the life table approach when these cultural

practices are instituted, as in tomato production in South Florida.





83






84


Although the two Experiments were planted in different areas in

1975 and 1976, mole crickets, cutworms,and damp-off caused damage on

both fields. This fact indicates that these pests are ubiquitous and

cover an extension of land. The level of infestation, however, is likely

to differ in other areas of Florida. Even in the same field, the damage

was never uniform in the plots.

During 1975, cutworms were the most important mortality factor

acting throughout the Transplant period of tomato growth. The average

of the three plots was 3.0% of plants killed, equivalent to 192 plants

lost based on 6,400 seedlings per acre.

The economic impact is in direct relation to the damage. The

average loss of revenue for the three strategies was $62, but the

reduction in each was different: higher in the Management ($80) and

Commercial ($79) strategies, and lower ($42) in the Check. These dif-

ferences are present, due to the fact that the estimated potential

revenue for each approach was different. In the Management this was

$2,661, in the Commercial it was $1,993, and in the Check $1,382.

When the maximum yield over the two seasons is used to estimate

potential revenue, it is equal to $2,880. Based on this figure a

more realistic economic impact can be obtained. Each plant lost

(1.0%) is equivalent to $29 (Tables 27 to 32). Based on this point

of view, 3.0% of plants killed would represent an economic impact of

$87 per acre.

The 1976 gross dollar potential for tomato fruits was well above

1975 values on Management and Commercial approaches. All mortality

factors increased the extent of damage and reduced dollar revenue in

1976.






85


Cutworms were the second important mortality factor during the

Transplant period in 1976, The average damage of the three plots was

4.3%, 1.3% higher than that in 1975. Plant loss was 277 and the average

economic impact was $76 per acre, approximately $14 higher than that

for 1975. The economic impact per acre differed in each strategy,

depending on the potential revenue per acre. High differences were

observed between the Check approach during 1975 and 1976, with respect

to damage caused by cutworms. The difference is due, in part, to the

differences in the potential dollars revenue, $1,382 in 1975 and $922

in 1976.

The second most important mortality factor was mole crickets,

during the first period in 1975. The pest caused, on the average, loss

of 2.3% plants per plot, equivalent to 147 per acre. Again, this

damage translated to economic values per acre, shows variation depend-

ing on the estimated potential revenue. Thus, for Management was $54, for

Commercial $40 and for Check $42, but the average was $46 per acre.

This value was Ca. 26% lower than that occasioned by cutworms.

In contrast with the abundance of mole crickets in 1975, in 1976

the infestation was higher and the pest was the most important mor-

tality factor during the Transplant period. They destroyed 5.0% of the

plants per plot, on the average, approximately 320 per acre. The

economic impact was $133 per acre, almost three times higher than the

value for 1975 for the same growth period.

Damp-off was the third mortality factor during the Transplant

period in both experiments, 1975 and 1976. The average of plants lost

was 2.0%, but the economic impact was $36 for 1975 and $57 for 1976

per acre, on the average.






86


During the Transplant period of tomato development the mortality

factors, together, accounted for reduction of revenue of $144 in 1975

and $266 in 1976 per acre. This fact indicates that the damage was

higher in 1976 and that the economic impact depends not only on the

level of pest infestation but on the potential revenue of the crop,

such as it appears on Tables 27 to 32, and on the season.



Bloom Period


During the Bloom period of development, plants were not affected

as severely as during the Transplant period by soil pests since the

growth had started, the stem increased in diameter and the roots were

firmly established. But, some plants were yet in a susceptible stage

to disease agents persistent in the soil. This fact and favorable

weather conditions permitted damp-off damage during the Bloom period

in 1975 and 1976. The economic impact, per acre, in the first experi-

ment averaged $29, in the second experiment $22, although the first

had twice the damage of the second one in terms of numbers of plants

damaged.



Fruit Set Period


During the Fruit Set period, plants suffered relatively lower

damage in both Experiments with exception of the loss occurred in the

Check plot during 1976. One disorder caused by deficiency or low

availability of Ca, in the soil, diminished 38.0% of the surviving

plants. The economic impact, per acre, reached $349. This was the most






87



important mortality factor recorded during the Fruit period in both

experiments. Soil pests caused damage only in the Commercial and Check

plots in 1975; the economic impact per acre was $16.




Maturation Period


The effect of cull factors on fruit quality and quantity was more

pronounced at the harvest time. No attempt was made to determine the

effect of leafminers on production, since the infestations were rela-

tively low and also because Levins et al. (1975) report that leafminers

in low populations do not directly affect yield.

Insects, diseases and mechanical damage were the cull factors

detected at the time of harvest. Mechanical and disease damage were

caused by the same factors during both Experiments, but insect species

attacking fruits varied from one year to the other.

Heliothis spp. and armyworms were responsible for all fruit culled

due to insect damage in 1975. The Commercial plot received 10 sprays

with methomyl plus dimethoate, however fruitworms caused 9.10% of cull

fruits, equivalent to $162 less per acre. The Management plot received

5 sprays, but besides Heliothis spp., armyworms were present.

Together they caused a loss of $282 per acre and damaged 11.5% of the

fruits. In the Check plot, Heliothis spp. injured 20.0% of the fruits

and reduced the revenue in $249 per acre. The differences within

percentages of damage and economic impact, stressed the fact that the

potential revenue (high or low value crop), and the number of fruits

damaged would have great influence on the calculated reduction of

dollars per acre. The number of fruit damaged in the Management plot

were equal to those damage in the Check plot, but the damage in the first





88



was 11.5%, while in the second it was 20.0%.

Due to the lack of uniformity with respect to the damage caused

by Heliothis spp., the percentages of damage during 1975 support those

given by Wilcox (1956), Middlekauff et al. (1963), Harding (1971) and

Oatman and Planter (1971). The results do not support those given by

Shorey and Hall (1963), Creighton et al. (1971), Creighton et al.

(1973) and Creighton and McFadden (1976), especially in relation with

the damage caused to the Check plot.

During 1976, Heliothis spp., pinworms and hornworms were respon-

sible for all the fruit damage caused by insects. No sprays were

applied on the Management plot, but the Commercial plot was sprayed

10 times in 1976.

Regardless of chemical applications, fruits were also injured in

the Commercial plot during the Experiment 2 1976. Insects damaged

7.2% of the fruits, 1.8% less than that of the Experiment 1 1975,

but the economic impact was $208 per acre, $45 higher than that of 1975.

In 1976, insects damaged 10.6% of the fruits of the Management

plot and reduced the income by $278. The values are not different

from those of the same strategy in 1975, although in 1976 the damage

was caused by three species of insects meanwhile in 1975 only one

species was recorded. This fact suggests that the damage caused by

different species, is not accumulative and that competition or, other

factors, affect the damage severity.

These results indicate that the damage caused by different

factors may be high in terms of number percent, but depending on the

crop value, the economic impact is variable. The damage varies from one

season to the other and the same mortality factors did not act with the






89



same intensity. The final effect is a result of the forces interacting

in the plant system.

The replication of life table in time and space is a sound idea

tending to obtain better knowledge of the constructive and destructive

forces that are active in an agroecosystem. Due to the complexity of

agroecosystems a team approach to pest management is advisable.




Insect Populations


During the Experiment 1 1975, the maximum infestation of Heliothis

spp. was 6 per 100 plants in the Management plot. This pest plus

Spodoptera spp. damaged 11.5% of the potential fruits. In 1976 in the

same plot, there were three species of insects: Heliothis spp. with a

maximum infestation of 4 larvae per 100 plants, pinworm with 4 larvae

per 100 plants and hornworm with 4 larvae per 100 plants, however, the

damage 9,0% of fruits was lower than that in 1975. This fact suggests

that there is not a direct relationship between pest numbers and fruit

damage and also that the damage is not accumulative.

Heliothis spp., in 1975, plus pinworm and hornworm during 1976,

caused 9.0% and 7.2% of cull fruits, respectively, in despite of 10

insecticide applications to the Commercial plot. It is possible that the

time of applications was inappropriate since older and larger larvae are

more difficult to kill.

The tobacco hornworm Manduca sexta (Joh.) was presented in the

Experiment 2 1976. The infestation was generalized on the three plots

and it was observed feeding on green mature fruits and accounted for the

loss of them, became a cull factor. The infestations occurred in the






90



last two weeks of sampling and near the time of harvest. So, this pest

could be one hazard for the fruits when the plants have finished their

physiological growth.

During 1976, infestations of aphids were relatively high (5,240

per 100 plants) in the Management plot compared to the other plots, the

same year and the previous year. No insecticide was applied because

there are no data on the economic impact caused by this insect to

tomato yield. High numbers of aphids were observed on one outside row

throughout the sampling interval, suggesting a particular spatial

distribution. The misunderstanding of this fact could result in one

unnecessary application of insecticide.

The maximum average of aphids (1,048) per plot was found on

May 7, and after this date the population declined drastically to 178

per plot on May 21. A sample taken on May 21 was analyzed and a Fusarium

spp. was identified. There is no previous report on this pathogen

attacking aphids,

From a total number of individuals captured by the pit-fall trap,

in the Management and Check plots, 59% and 65% were identified as

beneficial, respectively, meanwhile in the Commercial plot, only 48% were

beneficial. Insecticides reduced the number of beneficial individuals,

in Commercial plot 11% and 17% when compared with those of Management

and Check plots. No relation was found between Arthropods captured by

the pit-fall trap and pests attacking tomato plants.






91


Economic Analysis


The net return per acre, that is the benefit obtained minus the

cost of insecticides applied, was different for the three strategies

based on the value of fruits actually harvested. During Experiment 1,

the Management strategy showed higher ($1,881) net return, but during

Experiment 2, the Commercial was the best strategy. However, consider-

ing the average, the Management strategy had higher net return ($1,894)

than Commercial one ($1,751) in the two years.

Based on the potential maximum yield over two seasons,

Management and Commercial strategy showed no net return difference.

Consequently, the two strategies appear to be equally effective for

management of tomato pests.
















CONCLUSION


The purpose of this research was to construct a crop life table

for tomato production based on quantitative crop losses caused by

destructive pests and to evaluate the utility of the table as an

approach to identify determinant factors in the management of tomato

pests. Experiments were done over a two year period, two crop seasons,

in Gainesville, Florida,

The results of this study indicate that life table analysis is

useful in identifying and evaluating pests and strategies suitable for

tomato production. The information provided by crop and fruit life

tables could be used to improve pest management programs reducing un-

certainty and increasing benefits throughout a sound manipulation of

resources available. The format of life table permits not only an

insight into the effects of different mortality factors, but a direct

accounting of crop and fruit losses.

Crop life tables stress a multifactor approach in relation to crop

mortality and fruit loss. The destructive mortality factors acting on

tomato were cutworms, mole crickets, Heliothis spp., Keiferia lycopersi-

cella (Walsh.), Manduca sexta (Joh.), Spodoptera spp., damp-off, soft-

rot (Bacteria), blossom-end rot and cracking (nutritional and physio-

logical disorders). Excessive mechanical damage of fruit was caused

by cultural practices made by hand. Also, a soil disorder accounted

for considerable crop mortality, especially in the Check plot during

the 1976 crop season.




92




Full Text

PAGE 1

CROP LIFE TABLES FOR APPRAISAL OF PEST INJURY TO TOMATOES By Jose Alonso Alvarez Rodriguez A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 1977

PAGE 2

ACKNOWLEDGMENTS I express my sincere gratitude to Dr. Sidney L. Poe (Chairman of the Committee), who directed the present study, for his criticism, assistance, and enthusiastic encouragement in the preparation of this dissertation. Appreciation is extended to Dr. Vernon G. Perry, Dr. Reece I. Sailer, and Dr. Stephen R. Kostewicz for their advice and critical review of the dissertation and for serving as members of the Supervisory Committee. Also, I thank Dr. Robert E. Waites for his help in the preparation of the land for the experiments. Gratitude is also expressed to Drs. Robert E. Woodruff, Frank M. Mead, Howard V. Weems, Jr., and Eric E. Grissell of the State Department of Agriculture and Consumer Services, Division of Plant Industry, Bureau of Entomology, for their help in the identification of species. Thanks are also due to the "Instituto Colombiano Agropecuario' : for financial support during the period of my graduate study. Finally, a very special gratitude is extended to my wife, Lilia, my children Carlos, Julio, and Luis and to my family who provided encouragement, affection, and moral support. i i

PAGE 3

TABLE OF CONTENTS PAGE ACKNOWLEDGMENTS ii LIST OF TABLES v ABSTRACT vii INTRODUCTION 1 LITERATURE REVIEW 3 Life Tables 5 Tomatoes and Cultural Practices 8 Tomato Pests Insects -q Soil insects ^1 Sucking insects n Foliage insects 12 Fruit and Foliage insects 13 Diseases ^7 Nematodes Weeds 20 MATERIAL AND METHODS 21 Experiment 1 1975 21 Experiment 2 1976 26 RESULTS 2g Experiment 1 1975 28 Management Plot 28 Life table 28 Economic analysis 32 Insect populations 32 Commercial Plot 34 Life table 34 Economic analysis 3^ Insect populations 3g Check Plot 3 8 Life table 3g Economic analysis 4q Insect populations 42 Experiment 2 1976 ^ Management Plot 42 Life table <2 Economic analysis 43 Insect populations ^ i i i

PAGE 4

TABLE OF CONTENTS Cont'd. PAGE Commercial Plot 47 Life table 47 Economic analysis 49 Insect populations ..... 49 Check Plot 51 Life table 51 Economic analysis 53 Insect populations 55 DISCUSSION 83 Transplant Period 83 Bloom Period 86 Fruit Set Period 86 Maturation Period 87 Insect Populations 89 Economic Analysis 91 CONCLUSION 92 REFERENCES CITED 96 BIOGRAPHICAL SKETCH 105

PAGE 5

LIST OF TABLES PAGE 1. Crop life table for tomatoes, variety "Walter," Gainesville, Fla. 1975 (Management plot I) 30 2. Estimated dollar loss by major mortality factor on tomatoes, 1975 (Management plot I) 31 3. Crop life table for tomatoes, variety "Walter," Gainesville, Fla. 1975 (Commercial plot II) 35 4. Estimated dollar loss by major mortality factors on tomatoes, 1975 (Commercial plot II) 37 5. Crop life table for tomatoes, variety "Walter," Gainesville, Fla. 1975 (Check plot III) 39 6. Estimated dollar loss by major mortality factors on tomatoes, 1975 (Check plot III) 41 7. Crop life table for tomatoes, variety "Walter," Gainesville, Fla. 1976 (Management plot I) 44 8. Estimated dollar loss by major mortality factors on tomatoes, 1976 (Management plot I) 45 9. Crop life table for tomatoes, variety "Walter," Gainesville, Fla. 1976 (Commercial plot II) 48 0. Estimated dollar loss by major mortality factors on tomatoes, 1976 (Commercial plot II) 50 1. Crop life table for tomatoes, variety "Walter," Gainesville, Fla. 1976 (Check plot III) 52 2. Estimated dollar loss by major mortality factors on tomatoes, 1976 (Check plot III; 54 3. Total fruits harvested and damaged by insects (I), diseases (D) and mechanical (M) per plot, 1975 56 4. Total fruits harvested and damaged by insects (I), diseases (D) and mechanical (M) per plot, 1976 57 5. Cost and benefits of alternative control methods for tomatoes 5g v

PAGE 6

TABLE PAGE 16. Total numbers of Myzus persicae (Sulzer) per plot, 1975. 59 17. Total mines of Liriomyza sativa e Blanchard per plot, 1975 60 18. Total larvae (1) and eggs (2) of Heliothis spp, per plot, 1975 61 19. Total larvae of Spodoptera spp. per plot, 1975 62 20. Total numbers of Myzus persicae (Sulzer) per plot, 1976 63 21. Total mines of Liriomyza sativae Blanchard per plot, 1976 64 22. Total larvae (1) and eggs (2) of Heliothis spp. per plot, 1976 65 23. Total larvae of Keiferia lycopersicella (Walsh.) per plot, 1976 66 24. Total larvae (1) and eggs (2) of Manduca sexta (Joh.) per plot, 1976 67 25. Pit-fall trap captures of arthropods in Management (M) Commercial (C) and Check (Ch) plots of tomatoes throughout nine sampling weeks. Gainesville, Fla. 1976 68 26. Total numbers of arthropods collected by pit-fall traps in Management (M) Commercial (C) and Check (Ch) plots of tomatoes during nine sampling weeks. Gainesville, Fla. 1976 75 27. Estimated dollar loss by major mortality factors on tomatoes, 1975 (Management plot I) 76 28. Estimated dollar loss by major mortality factors on tomatoes, 1975 (Commercial plot II) 77 29. Estimated dollar loss by major mortality factors on tomatoes, 1975 (Check plot III) 78 30. Estimated dollar loss by major mortality factors on tomatoes, 1976 (Management plot I) 79 31. Estimated dollar loss by major mortality factors on tomatoes, 1976 (Commercial plot II) 80 32. Estimated dollar loss by major mortality factors on tomatoes, 1976 (Check plot III) 81 33. Costs and benefits of alternative control methods for tomatoes 82 vi

PAGE 7

Abstract of Dissertation Presented to the Graduate Council of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy CROP LIFE TABLES FOR APPRAISAL OF PEST INJURY TO TOMATOES By Jose Alonso Alvarez Rodriguez March 1977 Chairman: Dr. Sidney L. Poe Major Department: Entomology and Nematology Qualitative, quantitative and economic effects of mortality and cull factors on tomato ( Lycopersicon esculentum Mill.) were studied and used to elaborate a crop life table as an approach to identify determinant factors in the management of tomato pests. Tomatoes were grown under Management, Commercial, and Control strategies in 1975 and 1976. During the Transplant period of tomato growth, cutworm ( Feltia spp.), mole cricket (Scapteriscus spp.) and damp-off (Rhizoctonia spp.) were identified as the major mortality factors. Collectively, cutworms, mole crickets and damp-off, during the Transplant period, affected 9.0% of the plants and reduced the potential income by $205 per acre. Damp-off also caused additional injury during the Bloom and Fruit Set periods. The average loss was 1.6% and $41 per acre. vi i

PAGE 8

Heliothis zea Boddie, Spodoptera spp. Keiferia lycopersicella (Walsh.), Manduca sexta (Joh.), soft-rot (Bacteria), blossom end rot, and mechanical damage, were the factors responsible for culled fruits during Maturation period. The damage caused by these factors was conditioned in part by the time and duration of the damage and also by the high or low economic value of the crop and by the control strategy followed. Averaged economic impact of these factors for the two year period was 24.0% for the Pest Management strategy, 19.0% for the Commercial strategy and 39.0% for Check strategy. The economic analysis indicates that for the two year term and with the hazards occasioned by the inappropriate use of insecticides in mind, Management strategy appears to be an approach to handle tomato pests as sound as current conventional. The results of this study show that life table analysis is useful in identifying and evaluating pests of tomatoes as well as for determining strategies most suitable for optimum tomato production. The format of life table permits not only an insight into the effects of different mortality and cull factors, but a direct accounting of production losses viii

PAGE 9

INTRODUCTION The tomato ( Lycopersicon esculentum Mill.) ranked second in value and third in acreage among the 22 principal commercial vegetables cultivated in the U.S.A. in 1973 (Anonymous, 1975). In Florida, the tomato is considered the most important vegetable crop, not only because of annual value but also because of the acreage planted ($148,700,000 and 31,500 respectively during 1975) (Anonymous, 1974). As is true for most cultivated crops, the tomato plant is attacked by several groups of pests insects, plant pathogens, nematodes, and viruses which individually and collectively at one time or another constitute serious threats. In many cases these pest species, along with competition from weeds, are limiting factors to tomato production (Porte and Wilcox, 1963). Growers are forced to apply chemicals, usually on a routine schedule, to eliminate much of the uncertainty caused by the threat of pests in tomato production. Environmental problems created by misuse of chemicals, resistance, eruption of secondary pests, regulations by the Environmental Protection Agency, limited product availability, and increased cost of chemicals, provide impetus to develop alternative approaches to pest control. Approaches that maximize production per unit area at minimum cost per unit of production and minimize chemical applications are needed. Such approaches must be based on a sound understanding of all components of the crop system (agroecosystem) Within the crop system the plant as well as its environment and pests, are dynamic sub-systems. Effective 1

PAGE 10

2 management of the system depends on knowledge of the interrelationships of these sub-systems. Prior to 1966, 20% of the tomato production costs in Florida were expended in controlling pests; this value increased to 25% during the last decade (Brooke, 1976). Although much information is available concerning specific controls for the various pests of tomatoes, there is little information on actual economic losses caused by the pest complex. No approach based on integrated management of pest populations affecting this crop has been implemented on a commercial scale. Pest management can only be justified in terms of its net contribution to human values, not only from the economic point of view, but from the biological, the ecological, and the social. Pest management consists of a combination of processes including acquisition of information from the agroecosystem and decision-making as well as the taking action to manage pest situations (Ruesink, 1976). Economic thresholds are considered one of the basic elements of a sound pest management program. Reliable information on crop losses due to destructive agents aims to establish increase profit, obtainable when these agents are controlled at an acceptable economic cost. This study was undertaken to determine, quantitatively, crop losses caused by destructive factors affecting tomato production. The methodology consisted basically of periodic sampling procedures intended to determine the main crop mortality factors, and the population dynamics of certain pests, especially insects. Experiments and data analyses were designed to construct a crop life table for tomatoes.

PAGE 11

LITERATURE REVIEW Pest management has gradually gained prominence during the past decade as a practical and sensible way to deal with pest problems. Pests are living organisms which occur in large enough numbers to harm man's property or values. Thus, population density is therefore a matter of primary concern to pest management (Geier and Clark, 1960, Huf faker, 1974). Moreover, populations exist as components of communities at various densities in a variety of ecosystems (Clark, et al., 1967). An ecosystem is a system composed of living organisms and non-living environmental factors interacting to produce an exchange of matter and energy in a continuing cycle (Odum, 1971). The parts of an ecosystem which determine the existence, abundance and evolution of a particular population are collectively called the life system of the population. It is usually composed of both the population and its environment (Clark et al. 1967). Pest management has been defined as "the intelligent reduction of pest problems by actions selected after the life systems of the pests are understood and the ecological, social and economic consequences of these actions have been predicted, as accurately as possible, to be in the best interest of mankind" (Rabb, 1970). Pest management is now generally thought of as a final goal achieved through intelligent direction of effort over an extended period. The goal is threefold: 1) manipulation of available resources to hold pest populations below economic damage levels; 2) avoid or reduce disruption of the environment by decreasing the need for protective use of pesticides and 3) assure 3

PAGE 12

A crop production levels needed to meet the needs of an increasing human population. From these points of view, pest management has a broad ecological, economic base and two fundamental guiding pricniples. The first is to consider the life systems of pests and the second principle is need to establish and utilize critical injury levels (Geier and Clark, 1960, Smith, 1969, Rabb, 1970, Huffaker, 1974, Ruesink, 1976). Agroecosystems are man-influenced agricultural crop systems. Due to their non-natural state they differ markedly from natural ecosystems (Solomon, 1972, Springett, 1972). While less complex than natural systems, agroecosystems are very complex and dynamic in function. They are intensified systems in that different resources (inputs) are integrated to maximize agricultural production per unit of area. Many of the technologies developed to achieve this goal have resulted in increased plant pest problems (Apple, 1972). Increased pest problems, in many cases, created by crop cultural technology have required routine application of chemicals in order to maintain production. The occurrence of resistance, environmental contamination by chemicals, residues, resurgence of pests, and eruption of secondary pest populations have created serious problems. To deal with these problems pest control must be founded on a more sound ecological basis (Smith, 1970). Crop yield and quality have been shown to be determined by several factors: variety, soil, fertilizer, environmental conditions (temperature, moisture, radiation), cultural practices, and in greater or lesser degree by the pests (insects, diseases, nematodes, weeds, etc.). In undertaking pest control actions with chemicals, the farmer attempts to reduce damage caused by pest populations, to insure the revenue from his crop by assuring harvest of all potential yield. The use of pesticides rarely increases yield, rather pest control serves to defend or protect what

PAGE 13

5 would be produced in the absence of pest competition (Ordish, 1962, Southwood and Norton, 1972, Luckman and Metcalf, 1975, Headley, 1975). In reality farmers are faced with uncertainty (risk) concerning weather and possible damage by pests ^so chemicals are used to reduce the uncertainty and thus to protect the capital investment. On the other hand, populations of both pest and non-target species are functional parts of agroecosystems and any alteration of the environment should be carefully monitored in order to avoid disruptive effects that could result in disastrous consequences (Rabb et_ a_l. 1974). For pest management to be on a sound ecological basis and to be helpful in reducing uncertainty, basic information is required in crucial areas such as population dynamics of the pests and the economic thresholds of the crop systems. This information will provide a basis for decisions with respect to management alternatives that either maximize or complement the action of those processes that reduce pest populations below economic levels (Campell, 1971, Way, 1972, Varley et al 1974). To get the needed information, an interdisciplinary approach has been emphasized in which the simultaneous study of all involved factors must be integrated (Benham, 1972, Bar, 1972, Giese et al 1975). Life Tables It is evident that there should be a basic understanding of the relationship between pest infestation levels and actual monetary crop losses. Therefore, it is necessary to determine economic thresholds, that is the maximum pest population that can be tolerated at a particular time and place without a resultant economical unacceptable crop loss (Stern et al. 1959, Luckman and Metcal, 1975, Way, 1972, Smith, 1969, 1971). Headley (1975), emphasized that this concept is an

PAGE 14

application of standard economic costs and return analysis, or in other terms, cost/benefit analysis. Chiarappa et al, (1972) stressed the fact that little reliable information on the magnitude of crop losses is available. Crop loss information can be used both to reduce the risk faced by the farmer and to eliminate unnecessary use of chemicals. Methodology for cost/benefit analysis can be found elsewhere (Smith, 1971, Southwood and Norton, 1972, Headley, 1975), Crop life tables have been used as a tool for cost/benefit analysis and Luckman and Metcalf (1975) emphasized that such an approach provides excellent guidelines in the planning of pest management. Crop life tables are modified from the life table concept of ecology. A life table is a concise summary of certain characteristics of a population; it states for every interval of age, the number of deaths, the survivors remaining, the rate of mortality and the expectation of further life (Deevey, 1947). Hett and Loucks (1968) used life tables to analyze the dynamics of three species of forest trees. They concluded that the three species examined have a negative exponential distribution of numbers with age, indicating relatively constant germination survival, mortality rates and population structure over the ages studied. The changes in survivorship rates appear to be a result of differences in shade tolerance between the three species. Waters (1969) demonstrated that crop life tables provide a logical format for the full record of birth, growth, and death of trees in forest stands. Mortality and other losses in volume and value due to destructive agents were recorded by cause at the time or in the period they occurred.

PAGE 15

Harcourt (1970) made the first use of life tables for analysis of pest damage and cost/benefit in cabbage pest management in Canada. Under non-treated conditions he found that young plants have highest mortality, and that cutworms, cabbage caterpillars, and root maggots were major mortality factors. Taken together, insects caused losses of $317.47/acre, diseases $34.18/acre, and miscellaneous factors (mechanical damage, rodents, weather, etc.) $26.01/acre. Operating profit at $436.30/ acre was just over 50% of potential revenues at the time of planting ($813.96/acre). Crop life tables differ from insect life tables by: 1) the survivorship record is obtained from periodic sampling of the same population and the same individuals; 2) the population (and, therefore, the crop life table) is "closed-ended," i.e., there is no recruitment through births or immigration, and the population is terminated by a harvest; 3) the percentage values for successive mortalities are in absolute, rather than relative terms, i.e., all are calculated from the number of plants alive at the start (Harcourt, 1970). Napompeth and Nishida (1974) reported that the main factors causing damage in sweet corn were: 1) lack of pollination and 2) corn earworm. Loss of revenue per acre was $1,471 and $500, respectively. The same authors concluded that there are two ways to utilize crop life tables: 1) assessment of actual mortality of plants during the growth period and 2) assessment of losses or mortality in terms of dollar value of the crop. Hall (1974), utilizing crop life tables in apples, found that without insecticides fruit quality and yields were reduced by 45% and 85%, respectively. When injury from insects or diseases was severe, grading required extra personnel and the speed of this operation was reduced

PAGE 16

8 resulting in increased production costs. Tomatoes and Cultural Practices The tomato, Lycopersicon esculentum Mill., a member of the family Solanaceae, is a native of tropical America. Plants are herbaceous, procumbently branched and partially erect, bearing fruits, a berry, in clusters. There are determinate and indeterminate growth types. The size and shape of the fruit varies with the cultivar. It is a warm-season plant and shows a wide climatic tolerance and can be grown in the open wherever there are more than 3 months of frostfree weather. It thrives best when the weather is clear and rather dry and temperatures are uniformly moderate (65F to 85F) Plants are usually frozen at temperatures below 32F and they do not increase in size at temperatures above 95F. If the night temperature stays above 85F, the fruits do not become completely formed (Jones and Rosa, 1928, Thompson, 1949). Methods of plant growing differ. Tomato plants are started either in special plant-growing structures or by planting directly in the field. Methods of starting plants include: hotbeds; cold-frames; open-beds; greenhouses and direct seeding in the field. Setting plants in the field is done either by hand or by transplanting machinery. Tomato seedlings should be transferred to the field with as little shock as possible. The preservation of a large amount of the original root system is probably unimportant. If the plants are "hardened" to prevent immediate desiccation, they will form a new absorption system very quickly. The planting distances vary with the locality and methods of cultivation from 1-12 to 4 feet apart in rows that are from 3-1/2 to 6 feet apart

PAGE 17

9 (Jones and Rosa, 1928, Porte and Wilcox, 1963, Kelbert et al 1966, Stephens, 1973). A number of cultural practices for tomato growing have been developed through the years. Unless mulch is used, frequent shallow cultivation should be given as often as is necessary to stir the soil and to control weeds (Thompson, 1949, Porte and Wilcox, 1963). The amount and kinds of fertilizers to apply economically for the tomato crop depend not only upon the available fertility of the soil, but also upon the organic content, moisture supply, season, cropping system, cultivar, etc. For best production, however, special attention must be paid to the time of application and sources of nitrogen, phosphorus and potassium (5 pounds of nitrogen, 2 pounds of phosphorus and 8 pounds of potassium are required to produce 1,000 pounds of tomatoes (Kelbert et al. 1966). In Florida, polyethylene mulched crops are given a total of 200 to 400 pounds of nitrogen, 100 to 450 pounds of phosphorus, and 400 to 550 pounds of potassium per acre in addition to minor elements and lime to bring the soil reaction to pH 6.5 (Jones and Rosa, 1928, Thompson, 1949, Wilcox and Langston, 1960, Geraldson, 1963, Wilcox et al. 1962, Marvel and Montelaro, 1966, Jaworski, 1965, Murphy, 1965, Kelbert et al. 1966, Bryan and Strobe] 1967). Important factors in growing tomatoes are an ample water supply and facilities for rapid drainage after heavy rains. Sufficient moisture should be present for germination or quick recovery of transplants and to keep the plants growing well without wilting. Excess of water during harvesting increases cracking of the ripening fruits (Porte and Wilcox, 1963, Kelbert et al., 1966, Locascio and Myers, 1974). Any material used to cover the soil around the plants is called

PAGE 18

10 a mulch; presently in Florida polyethylene plastic mulch is the most used material. As with any cultural practice, plastic mulch has advantages and disadvantages as pointed out by Geraldson (1962), Kelbert et al. (1966) Wolfenbarger (1967), Davis et al. (1970), Stephens (1973), Locascio and Myers (1974) The value of pruning and training tomatoes varies considerably with different localities, seasons and cultivars. These practices are intimately associated with economics of the crop so that no specific recommendations can be made. Various methods of pruning and tying are followed, but pruning to a single stem and tying the plant to a stake are the most common. Ground culture is practiced when no artificial means of support is provided for the tomato vine; usually the suckers are not removed and the plant takes the appearance of a bush rather than vine. Pruning the suckers is common in staked systems in which the main stem is tied to a stake (Jones and Rose, 1928, Porte and Wilcox, 1963, Kelbert et al., 1966). Removal of 4 to 7 branches for determinate type plants has been shown to increase fruit at the 3rd, 4th and 5th harvest (Burgis and Levins, 1974); but the same authors, working with the determinate type "Walter," showed that 3 prunings caused plants to produce the highest total number of 13.61 kg cartons, followed by 0, 6 and 9 prunings. Market value was at a maximum for 9 prunings. Other details about advantages and disadvantages of pruning and training are given by Kelbert et al. (1966)

PAGE 19

11 Tomato Pests Insects Soil Insects The most common soil insect pests associated with tomato crops are cutworms, Feltia subterranea (Fab.) and Agrotis spp.; mole crickets, Scapteriscus spp.; lesser cornstalk borers, Elasmopalpus lignosellus (Zeller) All of these insects can chew or cut the stems of seedlings at ground level, causing them to fall over and die. They are especially troublesome during the 2-3 weeks immediately after transplanting. Cutworms also feed on the leafy parts of the plants. Besides direct damage, mole crickets also cause mechanical damage by burrowing in the upper soil causing the soil and roots to dry out (Hayslip, 1943, Stephens, 1973, Short and Driggers, 1973, Poe, 1976). The control of the soil insect pests has been based on chemical treatment recommendations (Johnson et al. 1974, Short and Driggers, 1973). Short and Driggers made recommendations for mole cricket control, based on the behavior of the insects according with their life cycle. Poe (1976) indicated that the number of mole crickets in field populations could be estimated by the number of burrows and concluded that untreated canals and/or untreated fields are sources of mole cricket reinf estations for the treated lands. Sucking insects The most common sucking insects attacking tomatoes are the green peach aphid, Myzus persicae (Sulzer) the potato aphid, Macrosiphum euphorbiae (Thomas), and the green stinkbug, Nezara viridula (L. ) Aphids attack the young, tender leaves, suck out the juices, and often serve as vectors of mosaic disease pathogens on tomatoes. Stinkbugs damage fruit by sucking juices, causing them to either fall or develop abnormally or with discolored areas. Damage

PAGE 20

12 caused by stinkbugs are recognized by the presence of a round, white, cloudy blotch, 1-10 mm diam. just below the surface of the fruit; sometimes the fruits are classified as culls (Stephens, 1973, Chalfant, 1973). It is not usually necessary to make separate chemical applications against aphids and stinkbugs, they frequently are controlled by insecticides applied against leafminers or fruitworms (Johnson et al. 1974). Shorey and Hall (1963) reported that aphids seldom occur in densities which could directly impede plant growth, and it is doubtful whether conventional insecticide treatments are of value in suppressing insect borne birus diseases in tomatoes. Some cultural practices have been explored to control aphids. Wolfenbarger (1967) showed that the incidence of mosaic-virus was delayed by using aluminum and plastic as mulch in tomatoes. He stated that aluminum surfaces repel aphids. Chalfant (1973), using a scale of 1-5 for classification, showed that potato aphids caused damage of 4.7 on vines in untreated plots; he used a scale of 1 = no damage, 5 = severe leaf burn and distortion. In plots treated 6 times with chemicals the least damage was 1.8; no mention was made on infestation densities. Also, the same author demonstrated that Nezara viridula (L.) caused damage in fruits of 17.4, 20.0 and 22% (1969, 1970, 1971 respectively) in untreated plots whereas, in treated plots, the least damage was 7.8% with 4 applications (1969); 0% with 6 applications (1970); and 0% with 6 applications (1971). Again, no mention was made of densities. Foliage insects Leafminers, Liriomyza sativae Blanchard and loopers, Trichoplusia ni (Hub.), are common species that attack tomatoes. Wolfenbarger (1947) reported that both larvae and adults of leafminers caused damage on tomato plants. Leafminers have been the subject of many studies including biological and chemical controls

PAGE 21

13 based on prevention (Wolf enbarger 1954, 1958, Hills and Taylor, 1951, Wene, 1953, 1955, Baranowski, 1959a, 1959b, Shorey and Hall, 1963, Harding, 1971, Poe 1974b). Throughout these studies it has been shown that the use of some insecticides would cause disruptions of leafminer populations, either by killing parasites or by inducing resistance (see Poe, 1974b, Musgrave £t al. 1975, and Oatman and Kennedy, 1976). The potential of other alternatives of control, such as plant resistance, was explored by Webb et al. (1971). The effect of stake and mulch cultures of tomatoes on the response of leafminer and its parasites was studied by Price and Poe (1976). They found that stake and mulch cultures have a positive influence on leafminers and their parasites, so tomatoes, grown under these methods must receive greater care in pest management programs. Little refined work has been done on the effect of leafminer populations on tomato yield. Wolf enbarger and Wolf enbarger (1966) stated that the threshold for leafminer was at an average of 1 or more mines per each leaflet of a leaf. However, Levins et_ al. (1975) concluded that there was no evidence that leafminers directly affect tomato yields, and emphasized the importance of recording yield quality and quantity as well as population responses in pesticide trials. Fruit and Foliage insects Some insects which feed on foliage are also included in the category of fruit feeders, notably tobacco hornworm, Manduca sexta (Joh.), Southern armyworm, Spodoptera eridania (Cramer), beet armyworm S. exigu a (Hub.), tomato pinworm, Keiferia lycopersice lla (Walsh.), and the properly named tomato fruitworm, Helio this zea (Boddie) There is much information about this insect pest complex and in many cases publications refer to two or more species, however, past and present studies indicate that armyworms and fruitworms

PAGE 22

14 are the most serious pests of stake tomatoes in Florida (Poe, 1974b). Madden (1945) studied the biology and some aspects of population dynamics of tobacco hornworms. He concluded that parasites, predators and diseases, keep the pest population within certain limits, but none are of much value in "direct control." Middlekauff et al. (1963) found that infestations of hornworm resulted in damage to 12% of fruit in untreated plots, but Barrett et al. (1971) reported damage of 24% on green fruits and 9% on ripe fruits. Oatman and Planter (1971) demonstrated that releases of Trichogramma pretiosum Riley, increased by 10% the number of hornworm eggs parasitized. Creighton et al. (1971) found in untreated plots 270 hornworm larvae per 100 tomato plants, but no relation of this number to damage was indicated. Armyworms cause damage similar to that of fruitworms, but damage is usually more superficial and consists of shallow holes, less than \ inch deep on the sides of the fruit (Wilcox et^ al. 1956). No information about the relation of larval densities to damage was shown. Shorey and Hall (1963) reported reduction of armyworm populations from 142 to 12 larvae per 32 plants with 7 applications of chemicals. Middlekauff et al. (1963) indicated that armyworms caused damage to 11% of the fruits. Creighton et al. (1971) reported that in untreated plots, armyworms caused damage to 88% of the fruits. The pinworm, Keiferia lycopersicella (Walsingham) was first reported in the U.S. from Imperial County, California, in 1923, and since 1936 has been reported causing losses in late canning and market tomatoes (Elmore, 1943). This insect reached epidemic proportion in some localities in Florida, due to various factors (Wolf enbarger and Poe, 1973, Poe et al., 1975). Dissemination of the insect occurs by transporting young seedlings (Batiste et al. Swank, 1973, Poe et al 1975).

PAGE 23

15 Larvae feed in tomato leaves (leaf folder), young fruit, old fruit and stems; boring damage on fruit occurs during the latter half of the larval life cycle. A large proportion of the larvae enter the fruit core, beneath the calyx resulting in pin holes (Elmore, 1943, Wolfenbarger and Poe, 1973). Oatman (1970) stated that high temperatures and low or no rainfall provide favorable conditions for a rapid increase of pinworm. Middlekauff et al. (1963) found that uncontrolled infestations of pinworms caused damage to 12% of the fruits, but Harding (1971) reported damage at 20%. Wolfenbarger and Poe (1973) showed a general relationship in which use of chemicals reduced leaf injury and worm holes resulting in increased fruit yield, but after 9 chemical applications no relation was evident between leaf infestation and fruit damage, although they found infestations as high as 7.25 pinworms per plant in the check plot and as low as 0.5 in the treated plot. Also, Poe and Everett (1974) found no correlation among leaf mines, presence of larvae and fruit loss; however, they reported losses of 4.4% in number and 5.5% in weight in the untreated check, meanwhile, the best treatment had losses of 0.5% and 0.6% respectively. Poe et al. (1975) stated that integration of horticultural practices, choice of variety and chemical selectivity with early biological controls offer the greatest potential for pinworm management. They found that Apanteles dignus Musebeck and A. scutellaris Musebeck caused 50-60% mortality during late part of the season. Indeterminate varieties showed higher pinworm populations than determinate varieties. Insect growth regulators such as ZR-619 and ZR-777, used against pinworms, caused great mortality to the two parasites (Poe, 1974a). Wolfenbarger et al (1975) showed that leaf damage by larvae of the tomato pinworm reduced yield of tomatoes. The authors developed a

PAGE 24

16 sequential sampling plan for damage of the pinworm larvae, based on two spatial distributions; the Normal and the Poisson distributions. The fruitworm Heliothis zea (Boddie) has been considered one of the most destructive insects on tomato (Oatman and Planter, 1971), not only because of its capacity for damage but also because it is difficult to control. The main damage is caused when larvae feed on fruits, although leaves and stems are also attacked. Wilcox £t al. (1956) stated that half of the damage caused by fruitworms occurred in the first quarter of fruit harvest, but Middlekauff et al. (1963) reported that, in untreated plots, the number of injured fruits increased as the season advanced and averaged 27.7% when the second harvest was underway. Wilcox et al. (1956) suggested that one larvae per plant could damage between 2.2% and 8.6% of the fruits, and that 7 larvae per plant an average of 28.3%. They emphasized that 1 egg per 100 leaves could result in about 3% fruit damage; a heavy infestation was that able to cause 20% of fruit damage. Shorey and Hall (1963) reported that an average of 9.45% of the tomatoes in untreated plots were injured by the tomato fruitworm; Middlekauff et al. (1963) found a higher average of 17.6%. Oatman and Planter (1971) showed that biological control of fruitworms was effective on early plantings of processing tomatoes, using twice-weekly releases of Trichogramma pretiosum Riley at ca. 465,000/ acre. Parasitization of tomato fruitworm eggs was 5 times higher in the release field than in the control. Larvae caused 2.1% and 7.2% of fruit damage in the released and control fields, respectively. There is no uniformity with respect to damage caused by fruitworm larvae. The former references and the following illustrate such discrepancies. Harding (1971) reported 16.50%; Creighton et al (1971),

PAGE 25

61.0%; Creighton et al. (1973), 64.2% to 71.5%; Fery and Cuthbert (1974a), 13.1% to 17.3%; Creighton and McFadden (1976), 90.4% of fruit damaged in untreated plots. These data indicate that fruitworm is able to cause severe damage, but the damage grade could be different depending on the population density, area, crop season and stage of the crop. In some cases, yield quality and not quantity is affected (Shorey and Hall, 1963, Poe, 1974b). Tomatoes demand greater protection during the fruit set and maturation phases, and chemicals applied in these periods reduced the damage caused by insects (Poe, 1974b). The use of resistant varieties to reduce damage of insects in tomato has not been completely explored. A tomato cultivar with even partial resistance to the fruitworm would be of considerable value in a pest management program (Fery and Cuthbert, 1974a). Canerday et al. (1969) found a significant inverse relationship between number of fruit per variety and percentage of damaged fruit. Fery and Cuthbert (1975) reported the presence of a factor highly inhibitory to tomato fruitworm larvae, in leaves of Lycopersicon hirsutum Humb. and Bonpl. and L. Hirsutum f. Glabratum C.H. Mull. Diseases Tomatoes are subject to a number of diseases caused by fungi, bacteria, viruses and certain unfavorable soil or climatic conditions. Seedling diseases are not usually serious because fungicide treatment of seeds or fumigation of seedbeds or beds in the field reduce some of soil-borne fungal populations. However, there are soil-borne pathogens which are serious problems, especially those causing wilt diseases; Fusarium oxysporum (Schlecht.) f.

PAGE 26

lycopersici (Sacc.) Snyder and Hansen; Pseudomonas solanacearum E.F. Smith and Verticillium albo-atrum Reinke and Berth. Cultural practices together with chemicals have been used in controlling soil-borne pathogens. Gerald son e_t al_. (1965) reported that plastic mulch increased the effectiveness of fungicides in controlling systemic pathogens such as Fusarium and bacterial wilt; this is not the case with Verticillium wilt, because field fumigations do not eradicate the pathogen, but only delay the attack (Jones and Crill, 1975). However, marketable fruit was increased by paper or polyethylene mulch, because of improved wilt control and a better distribution of nutrients and moisture (Jones et al. 1972). Jones and Woltz (1972) found that the incidence of Verticillium increased and that of Fusarium wilt decreased by raising the soil pH, from 5 0 to 7 0 or 7 5 On the other hand, Woltz and Jones (1973) indicated that a combination of high nitrate, low ammonium, and lime affected Fusarium wilt adversely. Jones and Crill (1973) made a summary of the yield reduction caused by Verticillium wilt. They reported conflicting views and suggested that different races could cause different damage depending on the variety. This disease can cause reduction of yield on tomatoes as high as 68% on susceptible varieties, 39% on tolerant and none or slight on resistant varieties. There are other diseases recognized as pest problems on tomatoes which require chemical control but information about their reduction of yields is scarse. Such diseases include: late blight, Phytophthora infestans (Mart.) dBy; Phytophthora parasitica ; early blight, Alternaria solani ^ Eli and Mart.) Jones and Crout; Rhizoctonia solani Kuehn; bacterial spot, Xanthomonas vesicatoria (Doige) Cows; soft-rot, Erwinia caratovora (L. R. Jones) Holland.

PAGE 27

The most prevalent virus problems in tomato are tobacco mosaic virus (TMV), potato virus (PVY) tobacco etch virus (TEV) and to a lesser extent, pseudo-curly top disease. Apnids can be vectors of PVY and TEV, and Micrutalis malleifera Fowler is vector of the pseudo-curly top disease. Loss from these diseases have never exceeded 5% (Simons, 1962). Early inoculation 8 days after field planting, with TMV, reduced yields of tomatoes significantly more than late inoculation, at 10 weeks after field planting (Weber, 1960, Crill et al (1970). Nematodes There are few data relating losses to nematodes on tomatoes. Some of the more common nematodes which damage tomato roots are root-knot, Meloidogyne spp., rehiform, Rotylenchulus sp., sting nematodes, Belonolaimus spp., stubby-root, Trichodorus spp., root-lesion, Pratylenchus spp., stunt, Tylenchorhynchus spp. Root-knot nematodes can be extremely severe pests on tomatoes on lands that have been cultivated for a long time. Many of these nematodes may cause drastic yield reductions unless effectively controlled. Good cultural practices and/or chemicals prior to nlanting, reduce damage caused by nematodes (Kelbert et al., 1966, Johnson et al 1974). Although yield reduction of tomatoes has been associated with root-knot nematode infection by Hays lip et_ al. (1952), and Walter and Kelsheimer (1949), publications by Overman and Jones (1968), and Overman (1975). indicated no relation between nematode populations and fruit yield. Potation with pangolagrass pastures has been recommended to reduce or eliminate certain problems caused by soil-borne diseases and nematodes in old lands (Hayslip et. al_. 1964).

PAGE 28

Weeds Weeds compete with tomato plants for water, nutrients and sunlight. Weeds also harbor insects, plant pathogens and nematodes. The effects of weed presence, and influence on tomato yields, depends on several factors such as type of soil, moisture, season, rotation practiced, and of course, are different from one area to another. Some of the most common weeds found in Florida are crabgrass, Digitaria sanguinalis (L.) Scop.; goosegrass, Eleusine indica Gaertn.; bermudagrass Cynodon dactylon (L.) Pers. Others are annual sedge, Cyperus spp. ; Aclipta eclipta Eclipta alba L. (Hass.); common pigweed, Amaranthus spp.; purslane, Portulaca spp.; nightshade, Solanum spp. (Burgis, 1973a, 1973b). Burgis (1973a) indicated that data for 2 seasons demonstrated that there was reduction in both number and size of tomato fruits when no herbicide was used, but no data were given to support this assertion. He showed that several herbicides gave excellent control of weeds on row middles and in-the-row in mulched tomatoes, however, neither total yield nor fruit weight were increased significantly when compared with the checkhand weeded one, although the last practice gave 0.0% of weed control. Johnson et al. (1975) reported that a single application of selected pesticide combinations to control multiple pests (fungi, weeds and nematodes) on tomato transplants would increase yield by 41%.

PAGE 29

MATERIALS AND METHODS Experiment 1 1975 The objective of this experiment was to determine, quantitatively, crop losses caused by different destructive factors in tomatoes. Tomato plants used in this experiment were obtained as seedlings in trays of individual-cells from the University of Florida Agricultural Research and Education Center at Bradenton, Florida. Experiment 1 was done in a field of the Archer Road Entomology Laboratory in Gainesville, Florida. Plants were placed 17 inches apart in bedded rows on 40 inch centers. Fertilizer, 8:8:8, at the rate of 800 pounds per acre was banded on each shoulder of beds prior to transplanting. "Walter" tomato seedlings were set by hand on March 18, 1975, and three weeks later, 700 pounds per acre of fertilizer was placed between rows in all the plots. Overhead sprinklers provided moisture for the crop when necessary. Weed control was done by hand regularly and the plants were pruned and staked 6 weeks after transplanting. The experimental unit consisted of plots 29 feet long and 20 feet wide. The plot was divided into five rows 40 inches apart, planted with 100 seedlings, 20 per row. Each row was considered as one replication for recording data, and for analysis. Three plots were used during the experiment (Figure 1) To determine the range of different mortality factors on the yield, tomatoes were grown under 3 different strategies; a Management 21

PAGE 30

01 u u 0) o u u c , T3 a 3 Th St

PAGE 31

23 approach, a Conventional Commercial approach and an untreated Check. Although, in some cases, techniques to control individual pests were available, only chemical control of insects was applied in this experiment • Sampling techniques consisted of counting and recording the number of insects of each species per plot each week. Sampling began on April 1 and during the first 4 weeks all the plants per plot were checked. After April 29, due to the increased size of the plants, every other plant in each plot was checked. In spite of the volume of information available on tomatoes, no reliable data on economic thresholds for the major pests were found for using in the Management strategy. Based on the sampling data, a level of infestation was calculated each week and when this level was higher than a previously established economic threshold, an insecticide application was made, otherwise no action was taken. Levels of infestation (per 100 plants) considered as possible cause of yield reduction were as followed: 1) prior to fruiting, 15 larvae of Heliothis spp. and/or 10 larvae of Spodoptera spp.; 2) after fruiting, 6 larvae of Heliothis spp., and 15 larvae of IK. lycopersicella (Walsh.). To protect the plants against foliar diseases, 2 pounds per acre of 80% WP Manzate 200 was applied at weekly intervals. When deemed necessary, dimethoate 2.67 EC (1 pt per acre) plus methomyl (2 pounds ai per acre) were sprayed. Fungicide and insecticides were mixed, before application. Application was made with a hand sprayer and at volume of 50 gallons per acre during the first three weeks and' 100 gallons per acre during the remainder of growth period. Insects were counted from April 1 to May 29.

PAGE 32

The second strategy resembled conventional commercial practices of tomato production. The same fungicide and insecticides used as needed in the pest management block were applied to this block, but on a weekly schedule. The first application was made on March 25, the final one on May 29. Sampling for insects present on the plot were initiated on April 1 and continued until May 29. The sampling procedure was unchanged from that given for management strategy. The third strategy, or no control (Check) was chosen to determine the effect on tomatoes of the different factors. The plot in which this strategy operated received weekly application of the fungicide. The rate and application method was equal to those used for the other two plots. Applications of fungicide were between March 25 and May 29. The sampling procedure was similar to the other two plots. In an effort to determine the sequence of key factors acting during the time plants were in the field, five crop developmental stages were selected. Transplant period, extending from the time that seedlings were set in the field to first bloom was observed, a period of ca. 2 weeks and during which the root system became established. The Bloom period extended from the time of the first bloom until 50% of the plants had blooms, an interval lasting ca. 2 weeks. Fruit Set period extended from the time when 50% of the plants had bloomed until ca. 50% of fruit had set, a period of vegetative growth and fruit production lasting ca. three weeks. The fourth stage or Maturation period extended from the end of the third period until the appearance of mature green tomatoes, a period lasting ca. four weeks. The final stage was Harvest, a period lasting ca. four to six weeks. The crop developmental stages were used as a means to conveniently determine when certain mortality or cull factors have a significant impact

PAGE 33

on the number of plants, or on quality and quantity of fruit. These intervals do not necessarily represent physiological stages of development A complete inventory of plants per plot was made at the beginning of each of the crop development stages. Mortality records of the plants were taken every two or 3 days throughout the first three periods, the time during which the greatest potential for loss of plants occurred. All of the plants in each plot were examined on each recording date and when severe damage occurred, the plant was considered as dead. The data taken at each sampling interval was number of aphids per plant; number of new leafminer mines per plant; number of pinworm larvae per plant; number of larvae and eggs of armyworms, number of Heliothis and hornworms per plant. Unripe fruit injured by caterpillar feeding or disease was recorded at regular intervals beginning shortly after Fruit Set, the remaining fruit was allowed to vine-ripen. Then, the ripe fruits were harvested and sorted as marketable or unmarketable if damage by insects, diseases or other factors was evident. The first harvest was made on June 3 and the last on June 28. The format and symbols used for crop life tables in this experiment are the same as those used by Harcourt (1970). The first column, x, gives the sampling period, viz, the crop development stage; the second, lx, the number of plants living at the beginning of the period; the third, dxF, the mortality factor acting during the respective period; the fourth, dx, the number of plants lost within a specific period; and the fifth, lOOrx, is the percentage of mortality based on the initial plant population.

PAGE 34

26 The format and symbols used for fruit life tables in this experiment are patterned after those used by Harcourt (.19/0), but the values were estimated differently. The fruit population per plot was determined by the number of fruits harvested, thus the number of fruits for the transplant period is equal to the total number harvested plus the fruit lost or damaged throughout the different growth periods. The tabulation shows the impact of each cull factor in relation to those remaining fruits at specific time intervals during the season. This procedure was used by Hall, 1974. For the fruit life table, the first column, x, gives the sampling period; the second, lx, the number of fruits present at the beginning of the period; the third, dxF, the cull factor acting during the respective period; the fourth, dx, the number of fruits lost or cull fruits caused by the key factor, and the fifth, lOOrx, is the percentage of fruit lost based on those remaining fruits for the respective period. The number of fruits harvested per plot was used to estimate production per acre, based on 6,400 plants. Potential dollars revenue and loss per acre were calculated having in mind a sale price of $0.18 per pound of tomato, in accordance with Brooke (1976). Experiment 2 1976 The second experiment was planted on March 12, 1976 at the IFAS Horticultural Unit, at Gainesville, Florida. The objective, materials and methods and technologies used throughout Experiment 1 were followed in Experiment 2. Sprays were started on March 18, and suspended on May 21. The first harvest was made on May 22 and the last on July 7.

PAGE 35

Estimates of the fluctuation of soil arthropod populations were taken during the second experiment. A pit-fall trap was placed within each row per plot at ca. weekly intervals and an overnight catch was recorded. The arthropods collected were sorted and sent to the State Department of Agriculture, Division of Plant Industry, Bureau of Entomolo for identification. The collections were started on April 6 and ended on May 30.

PAGE 36

RESULTS Mortality and cull factors are noted separately, in the appropriate respective life table, as they were recorded in each growth period. The economic impact due to each factor is based on the percentage of damag and on 6,400 plants per acre as well as on the unit prices given by Brooke (1976). Experiment 1 1975 Management Plot Life table An analysis of tomato injury, using the life table format, is shown in Table 1. At the start of the Transplant period, there were 100 plants with a potential production of 1,225 tomatoes per plot. During that period, three mortality factors were present. Mole crickets caused 2.0% plant mortality which corresponds to a potential fruit loss of 25 tomatoes per plot, cutworms destroyed 3.0% of the plants which accounted for 37 potential fruits, and finally damp-off destroyed 1.0% of the plants corresponding to 12 fruits per plot. The total damage caused by these three factors, at the end of the Transplant period, was 6.0% of plants and 74 potential fruits per plot. At the beginning of the Bloom period, there were 94 surviving plants with a potential production of 1,151 fruits per plot. Damp-off was the only cause of mortality in this growth interval. A loss of 2.0% of plants (Table 1) was recorded, equivalent to 25 lost fruits per plot. 28

PAGE 37

Ninety-two plants began the Fruit Set period with 1,126 potential fruits per plot. No mortality factors were recorded during this third period. During the Maturation period three major factors affected fruits, here referred to as cull factors because the damage was restricted to the fruits. Heliothis spp. and Spodoptera spp. were the species of fruitworms recorded during the season on the Management plot; the total numbers of these species are given on Tables 18 and 19. Sorting of fruit damaged by each species was not possible so damage done by both species together accounted for the damage to fruit caused by insects. The damage figures in the Maturation period were recorded at the time of harvest. The potential number of fruit present at the start of this period was 1,126 per plot (Table 1). Insects were the major agent responsible for fruit damage and resulted in 11.5% loss in numbers per plot Three diseases caused loss on the fruits. Symptoms were identified as soft rot (bacteria), blossom-end rot, and cracking (nutritional and physiological disorders) (Tables 1 and 13). Together these diseases accounted for 2.3% of fruit lost, that is, 26 fruits per plot. Mechanical damage was the second factor of importance in Maturation period. The damage occurred mainly because of hand weed control practices and the staking and tying operations. The damage reached 6.1% of the fruits per plot, equivalent to 70 tomatoes (Tables 1 and 13). Insects and diseases, together, during the Transplant and Bloom periods reduced the plant population by 8.0%, corresponding to 99 fruits. All cull factors injured 20.0% of the potential fruits. At the moment of harvest 28.2% of the potential yield was recorded as fruits lost due to all the destructive factors throughout the four growth periods

PAGE 38

30 CO H 14-1 O C 01 U 03 H 01 Oh O o h U 0 VJ 4-1 OJ o a. h r-l o l-i 73 01 w a. rH O 3 CO C_> 14-1 T3 U V JO £ 3 4-1 o 0 4-1 4-) •H c H 01 a o a u o u i>i H OJ o (X B 4J o M rH 0) a 4J X S to u -a 3 G a sr-l a o rv u •H H U o 2 -X CM >4 E O 4-1 3 U o CM 3 3 o~ rH o o rH m 00 rH O OJ oi o vO CM o rH rH Ol O CM CM rn OJ rH u •H OJ > 0J Hi o H rH u o 3 3 C co r-l C X c ex) H H rH (a c_< crj 14-1 E IH 4-1 l-i o 0 o o 1 4-1 1 Q. 1 a. 4-1 E XI E 3 Rl 3 CO U Q CO Q 0) c o OJ a o iJ5 OJ OJ 0\ c 4J O 0) •H CO 4J E CO 4J r-l o •H 3 o 3 4J rH H CO PQ OJ O H oj OA •J) 01 > rJ CO 01 H -a OJ w 3 co u

PAGE 39

QJ 00 o rH in cD o rH rH CO o iH CO m CN CO CO s r. #\ cfl p-l CM OJ CN CM rH rH g o 4-1 m c |— | 0 0) U t-H o rd 4-1 V CNI c~> cO CM o o 00 CO o CO S-i CN CO vO CO CM o o oo H cfl CO u <4-< O CO co OA X CTv CO o o CN rJ u-i r>. CN m Ln rH rH CN 4-1 •H rH CO 4-1 M i— i 0 CO 5 4-1 „ cu (-1 ^ ^ o TJ CJ rH o S-i •I-t CO CM ct) CM o CO cfl U B ^M u H C e N o sn O o o CQ cfl o 1 4-1 i rH ;>% pc 0) 3 a. 1 a. 0) a) La rO rH 4-1 E >o E c c o o CC) 3 o o o m CJ P CO a z H CO CO CD o CO iH H CO Z M CO ,_] — 1 •4-J rH cfl CN \J 4_) Pu CM CM CM OJ CM CN CD CO CO e cd •H 4-1 CO CO w OJ (J C C 4J 0 rH cd CJ •H cfl CN £ T) H CO 4-1 4-1 > 01 4-1 O C. CO CO 3 -H Cfl E 4J M TJ 4-1 rH o u C o H 3 > rH CO rO. U CD cd o 3 4-J IH 0) o Cfl m rH M cd Cfl •H U H H S3 PC >> i— (

PAGE 40

32 (Tables 1 and 13). Only 900 tomatoes were classified as marketable of a total of 1,225 potential per plot. Economic a nalysis The impact of the major mortality factors converted into monetary values per acre, is shown in Table 2. The potential fruit production value per acre would be $2,661 of revenue. During the Transplant period, mole crickets caused a reduction of potential revenue of about $54 per acre, cutworms of $80, and damp-off of $25. The total estimated dollar loss was ca. $160 per acre. Damp-off was the only mortality factor in the Bloom period. The economic impact was estimated as equivalent to $54 per acre (Table 2). A potential revenue of $2,446 per acre was calculated for the Fruit Set and Maturation periods. The economic loss due to Heliothis spp. and Spodoptera spp. was $282 per acre, to diseases $56, and finally to mechanical factors $151, during Maturation period (Table 2). Taken together, insects caused losses of $417, diseases $136, and mechanical, $151. After subtracting losses due to damage by insects, diseases, and to mechanical causes an income of $1,956 per acre was obtained. This amount represents ca. 74% of the estimated potential of $2,661 (Table 2). The cost/benefit ratio per acre is shown in Table 15. Insecticides were the only variable involved, so I will only mention the cost of this variable. The retail price for insecticides for 5 applications was $75, thus, the net return $1,881 per acre, corresponds to 71% of the potential revene. Insect populations. The fluctuations of insect populations were recorded weekly and the results are shown in Tables 16 to 19. No infestations of pinworm were observed. Methomyl plus dimethoate were

PAGE 41

33 applied 5 times after April 29 against aphids, Heliothis spp, and Spodoptera spp. The two latter species of pests were persistent and the schedule of application did not eliminate the infestations or completely prevent damage. Armyworms ( Spodoptera spp.) were present only on the Management plot (Table 19) The average number of aphids per plot was significantly higher in the Management than in the Check plot during the 5 weeks before insecticide application, but the average number present after insecticide applications was reduced significantly and total elimination occurred May 27 (Table 16). The average number of leafminers ( Liriomyza sativae Blanchard) was significantly less than in the Check plot during the first three weeks of sampling but was not different from the Commercial plot average (Table 17). Heliothis spp. eggs were detected from April 1 and throughout the sampling period (Table 18). Despite the applications of insecticides after April 29, larval populations were present until the time sprays were suspended on May 29. The maximum number of eggs, per 100 plants, 4 was found on April 10 and the maximum number of larvae, per 100 plants, 6 was found on May 21 and 29 (Table 18). Spodoptera spp. larvae were observed on April 29, localized in rows 1 and 3, at such density that the decision was made to treat with insecticide. The application gave 80% control of the pest, the remaining 20% of the larvae caused damage on fruits recorded later during harvest.

PAGE 42

34 Commercial Plot Life table The crop life table format used for analyzing tomato injury is shown in Table 3. The Transplant period was initiated with 100 plants with a potential of 1,037 fruits per plot. This potential yield represents the total number of tomatoes harvested plus the number lost due to various factors. Three major factors of mortality acted on the tomato plants during the Transplant period. Mole crickets, and dampoff each caused 2.0% mortality, and cutworms 4.0%. These percentages represent a loss of 21, 21 and 41 tomatoes respectively per plot. The total damage due to these three factors, at the end of Transplant period, was 8% of the plants, and 83 potential fruits per plot. The Bloom period began with 92 surviving plants with a potential of 954 tomatoes per plot. Damp-off reduced the plants by 1.0% and this percentage corresponds to a loss of 10 fruits per plot. During the Fruit Set period, an additional loss of 1.0% was caused by damp-off. Ninety surviving plants began the Maturation period with 933 potential fruits per plot. Three major cull factors occurred in this period on fruits especially and were recorded in the harvest data. Heliothis spp, larvae were the only agents responsible for fruit damage and caused 9.0% loss, that is, 84 fruits per plot. Soft rot, blossomend rot, and cracking, accounted for 1.6% cull fruits per plot, while, mechanical damage was recorded as 6.4% of the fruits, equivalent to 60 tomatoes per plot. During the Transplant and Bloom periods, together, insects and diseases reduced the plant population by 10.0%. This percentage represents a loss of 104 potential fruits per plot. One hundred and fifty-nine tomatoes were recorded as cull fruits. Taken together

PAGE 43

35 4-1 O o 0) c u d i — I > m OJ C •r-l 0) O u 2 H M > to 0) o u d E o M o Mh (0 OJ 4-1 H a. o m rH ,P to H CO H M H rJ I4H o c 01 u Ph o c S-i -J £ 3 CJ a. 4-1 x W O T3 O H ^ rH a. o rH 4-1 rH O d to U MH M r-4 CD O. 3 0) z a. T3 t-4 0 4J •H 4J C rH 0) TO O 4J M U CD O ph e u CD A a 3 O o 4-J o rH p. /~\ QJ V — au o 1-1 o o TO -3 SH XJ 6 3 2 o 60 iH d p. •H > M •H CD • t-H p. 4-1 0 u o o CO 4-1 a o •H r-l o o -:< m o o o dJ u •H 'H O o o o 4-1 c n P. CO c d i-4 m OA O o TO CO e o 4-1 3 U o I p. e d p I a CO <4H lH o I 0 d n o o o o o o 00 CO E n o 4-1 3 U <4H 0 I d a i -a 3 oo o I p. e d P B o o i — i M ct: m o o "3 o 0J 1-1 4-1 co u TO o r-l £> E 3 C H d 3 4-1 o TO rH TO o. C 4-J 03 O O H TO T3 •H 0J C CO O TO 4-1 42 o o 4-1 O N o cn •H rH .C PCrJ M >^ OJ P. T3 CO 0J 4-1 ifi 3 3 T3 d u rH U a) •H >-*

PAGE 44

36 destructive factors accounted for 262 fruits lost per plot. From a potential production of 1,037 fruits, 775 were classified as marketable per plot at harvest (Tables 3 and 13). Economic analysis The economic impact of the major mortality or cull factors in the Commercial plot, in a per acre basis, is shown in Table 4. The estimated potential revenue would be $1,993, this value was reduced by $40, $78, and $40 by mole crickets, cutworms, and damp-off during the Transplant period. Together, these losses amounted to $159 per acre. Table 4 shows that during Bloom and Fruit Set period the economic impact due to damp-off was $38 per acre. The revenue from the fruits remaining at the beginning of the Maturation period was estimated at $1,795 per acre. From data in Table 4, it is evident that economic losses caused by insects was greater than that caused by pathogens or mechanical injury even when taken together. Insect losses amounted to $163, whereas losses to diseases and mechanical injury were $28 and $116 per acre respectively (Table 4). In the Commerical plot, during the four growth periods, insects reduced the potential revenue by $282, disease injury by $107, and mechanical damage by $116. After subtracting those values an income of $1,487 per acre was obtained. This amount represents ca. 75% of the calculated potential of $1,993 per acre (Table 4). Cost/benefit analyses are shown in Table 15. Insecticide costs for 10 applications per acre were calculated at $150; thus, the net return of $1,337 per acre, represents 67% of the estimated potential revenue.

PAGE 45

37 CD LO LP) CO u OJ CN CN C3 -1 CO (J o cti o CO o CT* CT\ CO CO CO r>. rH iH r— > o"> L/— j 1 4J 0 CO ,— 1 4. j Of Q) t y rH rH Cj [Tj CO *H 0] [d U-4 4_| CO (J cd •H on u J_l g tH r/) (U -H CJ H CJ o Q o Q 4j CO r i- n H N c 4-J 1 | CJ rr 4_1 >D CO cu cx | C CJ r* IX rH g i Q g g 03 09 CJ Q g Q r rj •-j CD o Q CO Q p 1 — i P CO u m H rH cfl o CTn H vO •H oj o m CN CM to 4-1 (-i US 4-1 a CJ •H u o o c CN cn cn E u c & 3 U rH 14H a >4H 14H UH 4-1 <4^ UH o 1 L 1 1 O 1 O 1 a. 1 c QJ E I" g C cfl 3 Cfl O P co Q P 2 4-1 O S iH O ^ 0) o a. 4-1 c Cfl a. as C to 14 H E O c iH o w •H r< c o CO rJ 3 cn ro m ro u-i vD cn ro m ro m m rH cn ON Ov oo co rrH rH rH tH rH CO > 33 CO JH o H •n

PAGE 46

38 Insect populations The numbers recorded for the insect populations are shown in Tables 16 to 19. Sampling was done weekly. Insecticide applications of methomyl plus dimethoate were started March 25 and continued weekly until May 29. Table 16 provides data which indicates that insecticides failed to provide 100% aphid control. However, the average number of aphids per plot was significantly lower in the Commercial plot than in the Management and Check plots during 6 of the 9 weeks of sampling (Table 16). The average number of leafminers ( Liriomyza sativae Blanchard) was significantly lower in the Commercial plot than in the Check plot only on 3 of the 9 dates of sampling. Data in Table 17 indicates that average numbers of this insect were not significantly different for the Commercial and Management plots. Heliothis spp. eggs were detected for the first time on April 10 and reached a maximum number of 4 per 100 plants on April 22 (Table 18) The first larvae was observed on April 22 and the maximum number (4 per 100 plants) were observed on May 29. This pattern of larval fluctuation and abundance suggests that insecticides did not eliminate the population. It is possible that the time of applications was inappropriate since older and larger larvae are more difficult to kill. Check Plot Life table Crop life table data for the Check plot are shown in Table 5. One hundred plants were present at the start of the Transplant period. Based on the number of fruits harvested, these plants represent 717 tomatoes per plot. Again, three major mortality factors were recorded during this growth period. Mole crickets killed 3.0% of the plants present, and consequently reduced the potential production by

PAGE 47

39 u o u a Xi u in 0> id i — I fa > J] o C •H GO H H P PS fa 14-1 o 3 o en o fa CJ E 3 Sa c o ex ^ O CD ^ — I P. u o rH 4-1 rH O 3 (0 C_> 14-1 O U rH CD cx J-J r4 01 ft E 55 >'. o CN cn CD a •H u 0 33 H m c 4-1 3 cj on c o o o o on O CN p 1 co m -:< 14-1 14-1 o 1 cx E rt n cfl 4-1 O rQ 0 I ex E P o I cx p o on CJ. en n CN O m to u •H c ra CJ CJ 1 -a 3 w ON CN O vD nC CN JX 0) (J H a] 12 4J OJ •H l-l CO > to CJ G 4J gj E o O cd cx o u CJ a) rH cfl 00 H hX Px o >n 3 0) CO o k4 0J cx u cd o o 4-1 0 ft e 03 r4 TJ 3 O 0) z rH a u o u CJ 43 s 3 3 o M u o a CJ o o o o o o CO o o o o O rH r4 •H DO 4H CO -:< O fa u E 4H 4-1 14-1 a c O 0 MH <4H u -a 0 1 XI O C Cfl CD ft 1 1 4H rH 4-1 ft PX OJ O a 3 E 3 s 0 P CO cfl O P P S3 4J O 00 rH c cx ^ •H X 0 CN rH O > )J H 0 C7\ ON •H CD s — rH rH ft 4-1 c c 4J 0 a CO •H XI rH co 4J O ft Cfl •rH ^ cn E 4J u r4 X c 0 •H 3 0) W CO 0 3 XJ ft U rH l-l id H m fa 7: o c o o i— o CJ > -J cfl C3 T3 rH CJ H PX PX 01 3 G 4-J CJ 0 N •H rC P< T3 CJ 4J f) 0 > x, Ih QJ xc B 3 3 cfl 3 xj U CO 3 G -a 0 0] n xj rJ r^ CD XI ft T3 QJ CO 3 id u •13 l-i fa -:<

PAGE 48

AO 22 fruits. Cutworms, also, killed 2.0% of the plant population, and damp-off was responsible for an additional loss of 3.0% per plot. These three key factors accounted for 8.0% of plants lost and a reduction of 58 tomatoes of the potential yield per plot. The Bloom period was initiated with 92 plants with 659 potential tomatoes per plot. Damp-off resulted in an additional 1.0% of plant loss equivalent to 7 fruits per plot (Table 5) Damp-off as mortality factor was recorded during the Fruit Set period, so, at the ending of this period there were 90 surviving plants with a potential production of 645 fruits per plot (Table 5). Three fruit cull factors were recorded for the Maturation period. The damage caused by these factors was observed at harvest. Insects injured 20.0% of the tomatoes, diseases 5.1% and mechanical factors, 5.0%. Together, these percentages are equivalent to 194 fruits lost per plot (Table 5) At the moment of harvest, 40.2% of the potential yield was recorded as fruits lost (266) due to all the destructive factors throughout the four growth periods (Tables 5 and 13). From a potential yield of 717 fruits per plot, only 451 were classified as marketable. Economic analysis The potential revenue per acre was estimated as $1,382 (Table 6). During the Transplant period, mole crickets reduced the potential revenue by $42, cutworms $27, and damp-off $42 per acre. The economic impact of the three mortality factors was $111 per acre. An additional reduction of $27 was recorded in the Bloom and Fruit Set periods (Table 6) For the Maturation period, a potential revenue of $1,243 per acre was calculated. Heliothis spp. reduced the potential revenue by $249

PAGE 49

41 o 01 x: O ITl 0) co m ro rH m DO 4H cn u •rH 4J U M 0 0 0 O 4-1 co c 0 o 1 4J 1 1 u a CO 4-1 OJ U o. 1 a tx ai 01 1 H 4J B B e CO co u G D 3 ra ra c •H 3J 3 u Q oo p O rH Q 5a CO o o c I oc ro ro CO r-s CI oO ro r in vlCN CN CS 00 00 rH rH rH o CJ •H o Q c o CN co ro rH to 14H ra 14H ch E 14H 4J M-4 lH M c 0 o O o 1 AJ 1 1 9 a 1 cx a 4J s s £ c ra ra ra o CJ O C/j Q a S3 c ra H c co C ra 0 o o rH r^ IH a c ra vC m CM rH o CN co ro CO m CO co 00 rH rro ro ro m U ra X ra o H

PAGE 50

per acre, diseases by $63 and mechanical factors by $62 during the Maturation period (Table 6) Throughout the four growth periods in the Check plot, insects were responsible for a reduction of revenue of $318, diseases $133, and mechanical $62 per acre. After subtracting economic losses due to the key factors, the estimated revenue was $869 per acre. This value is ca. 63% of the potential of $1,382 (Table 6). Therelative cost/benefit is shown in Table 15. The net return per acre was estimated at $869. No cost per insecticide was subtracted since the Check plot received no insecticide applications. Insect populations The insect population fluctuations based on weekly sampling are shown in Tables 16 to 19. Average numbers of Myzus persicae Sulzer were significantly higher than those in the Commercial plot on 7 of the 9 sampling dates, and higher than those in the Management plot during 8 of the 9 sampling weeks (Table 16). Average numbers of Liriomyza sativae Blanchard were significantly higher than those in the Commercial plot only during 3 sampling periods, and significantly higher than those in the Management plot, 4 times (Table 17). Heliothis zea Boddie eggs were detected the first time on April 10. A peak of major infestation, 6 larvae per 100 plants, was recorded on May 29 (Table 18). Experiment 2 1976 Management Plot Life table Crop life table data for the Management plot are shown in Table 7. Mole crickets were the most important factor causing

PAGE 51

mortality during the Transplant period. This pest destroyed 8.0% of the 100 plants present, and reduced by 120 tomatoes the potential of 1,498 per plot. Following in importance were cutworms which killed 3.0% of the plants, a value corresponding to 45 tomatoes. Damp-off affected 1.0% of the plants equivalent to 15 potential tomatoes per plot. At the end of the Transplant period, the total damage caused by these three factors was 12.0% of the plants and 180 fruits per plot (Table 7). No mortality factors were obc.er.ed ouring the Bloom and Fruit Set periods, thus the number of plants remained at 88 with a potential production of 1,318 tomatoes per acre. For the Maturation period the cull factors were insects, diseases, and mechanical damage. All these factors were recorded at the time of harvest. Three species of insects, Heliothis spp. pinworm (Keiferia lycopersicella ) and hornworm, were responsible for 139 tomatoes or 10.5% loss of the potential production. Symptoms of three diseases were identified, soft-rot (bacteria), blossom-end rot, and cracking, which reduced yield by 8.8%, approximately 116 fruits per plot. Mechanical damage resulted in a loss of 8.3%, 110 fruits per plot (Tables 7 and 14). As a consequence of all destructive factors throughout the four growth periods, 544 tomatoes were lost. Of a potential of 1,498 fruits per plot, 953 were classified as marketable (Tables 7 and 14). Economic analysis The economic impact of the major mortality and cull factors, on a per acre basis, is shown in Table 8. The potential revenue was estimated in $2,995. This amount was reduced by $239 due to mole crickets, $90 by cutworms, and $30 by damp-off, during the Transplant period. No additional losses were recorded for the Bloom and Fruit Set periods.

PAGE 52

44 co H M CJ W H < u 0 i — i ft — n 00 CT\ 6 n rH 4-1 -H C rH QJ CO CJ 4-J U U o o o o 0 rH ft X U T3 0) — ft >, 4-1 H H rH CO O 4-1 4-> 1-1 o O CO S mh T3 O BO rH cu 1 ft o H ft TO c c o o oo co rH o CN 1) o •H rl CJ o o c CO CJ H sn u o o o c CtJ rH ft CO C a M H O o o o in o CO CI m CO CO CN m St O CO o m m rH rH rH rH rH i — 1 rH n mh CO rH E >4H u CO a rd M O o co ai •H U 0 1 4-1 4J CO c o & ft 1 a) a rd CO 4-1 4J 6 a c QJ X. 1 rd a o 0 CO co o & u C 00 a c •H CJ P H n CO CO co co rH rH rH co CO co rH H rH c o o c o c o o o o o o CO e U c u 4-4 u c I B a Q I rO rd co 0) c o CO co B o o 1 — I cu C o co co 01 co 3 1-4 Lh 0) (3 o S5 oo CO c o cd H 3 4J rd st ON CO St ON o t o TJ O CN 4-J rH Efl CU > CJ ,c ki CM i— 1 g rH cd 4-1 C-j ft p CO Q rH CO cd rrj 4J .rH QJ O c CO H O CO j i pi rj o 4_( co oo N o CO CO • H — I r ft C£ J_l >, u rO ft TJ co 0) 4-J 4-1 CO •H CO 3 T) Cd M > rH U Ph OJ CO •H -:<

PAGE 53

cj — ( CNl O Q vC | ON CO vO X Q Q 1 — ) 1 — J m in ON CO rj — 1 o cfl CT on Q CD CO | CO co 00 in CO rH CN 00 CO r-""i CN L J o 1 — 1 1 i-H 4-1 o w 1— 1 Oh (U rH 4_j CJ ( 1 rH rj TJ *H CO It 1 rr* Cm CJ 03 QJ J_l V-* E 4J UJ J *T CO CO CJ n Q 1 ) 'Sj f— 1 VO QJ fn N Q £j 00 l—l CO cu *> r> Cm | QJ QJ ( U CJ 1 03 a rH B Q r* >— f— Cfl rj Q Cfl Q ri— i *H Hj m 2 r*^-< rj I — 1 I — i •-r 1 CO vO ON iH H cfl O CO CO CO H rH •H CO CO o O i-l 4-1 cr\ vC vO CTi ON cfl o 6 a, CN CN CN rH rH 0 CO H rJ a. a iH X> CNJ o o o cfl M VO CO ON o o o DO o 0 cfl ON 0> ON ON o o o >— 1 •COco CNl cc CN CO 13 cfl N ro x. Cfl H 01 4-1 U n cj 0) cfl 4-1 O P-, x: -a 4-1 o O >-i M 0) o a. ai u •H (-1 u o o in o> en e G -J 4J 3 CJ o I c 0 cfl Q x 3 on 0) 0) 1) c c C o 0 o £5 co CO CO 00 00 r-> r r~ r-~ m in UO m CO ro ro CO CO vO VO vO vO CN CN CN CN CNl c cfl H a in c cfl u H E o o I — I pq o> CO c c •H 4-1 rc 3 a) > cd CN m ro G H X cfl H -3 P Cfl vD c o )>l pq o CQ (U >-> cfl e CO CJ c o 73 0) CO cd X CJ 3 iH rc > CC o U

PAGE 54

46 Heliothis zea Boddie, Keiferia lycopersicella (Walsh.) and tobacco hornworm caused an economic damage of $278 per acre, during the Maturation period. Diseases reduced income by $232 and mechanical losses were estimated as equivalent to $219. The three factors were responsible for a reduction of $729 per acre (Table 8). In general, insects, diseases, and mechanical destructive factors had an economic impact of $1,089 per acre. After subtracting the estimated loss from the potential revenue, an income of $1,906 was obtained. This value represents 64% of the potential estimated per acre (Table 8). Since no insecticide was applied to the Management plot, the net return per acre was estimated at $1,906. Insect populations The number of insect populations recorded weekly are shown in Tables 20 to 24. Aphids were present during the season, but average number was not significantly different from those of the Commercial or Check plots. Maximum infestation (5,240 per 100 plants) was reached on May 7, and a minimum (25 per 100 plants) on March 25. A pathogenic infection of the aphid population was observed and from a sample taken on May 25 a species of Fusarium was isolated. High numbers of aphids were observed only on one outside row throughout the sampling interval (Table 20). The average number of leafminers was significantly higher than that of the Check plot on April 2, but was significantly lower than both the Commercial and Check plots, on April 23 (Table 21). Heliothis spp. eggs were detected on March 25 and reached a peak on April 30 (8 eggs per 100 plants). Larvae reached a peak on May 7 and two more on May 14 and 21 with an infestation of 4 larvae per 100 plants each time (Table 22). The maximum number of pinworms was detected on April 20 and May 7. On each sampling date, 4 larvae per 100 plants were found (Table 23). The hornworms occurred during the last two weeks of

PAGE 55

sampling. Four larvae per 100 plants were recorded on May 14 and 10 larvae on May 21. The arthropods collected by the pit-fall trap are shown in Table 25. The total number captured was 165 individuals (Table 26). Ninety-six (58%) of the individuals were identified as beneficial (predators, parasites, pollinators), 35 (21%) as pests (or pathogen vectors) and 34 (21%) as scavengers (especially members of Nitidulidae family) Commercial Plot Life table The typical analysis for the Commercial plot is shown in Table 9. From the 100 plants at the start of the experiment production was estimated at 1,600 tomatoes per plot. The Transplant period had three major mortality factors. Mole crickets and damp-off each affected 4.0% of the plants present and thus 64 fruits. Cutworms caused half as much damage, 2.0% of plants and 32 tomatoes per plot. Together these pests accounted for a loss of 10.0% of the plants and a reduction of 160 potential fruits. In the Bloom period, 90 plants were surviving with a potential production of 1,440 tomatoes per plot. Damp-off reduced by 2.0% of the remaining plants, equivalent to 32 additional fruits. No mortality factors were observed during the Fruit Set period, thus, 88 plants were present with 1,408 potential fruits (Table 9). The Maturation period was characterized by the action of three cull factors namely insects, diseases, and mechanical injury, which were again recorded at the harvest time. Heliothis spp., pinworm and horn-

PAGE 56

h8 o H P. u a o u r-. rtj rH •H > OJ c •H a o M cu JJ rH M a > 01 *j o 4J rtj E o M 0 mh x CO 0) H a. o M U a) rH n) Eh H rH CO H rJ C 01 o co CU fX rH o X E 53 'm o o p. ^ X >H X) Q) P. o rH 4-1 i-h a 3 CO U MH rH rH QJ O. rQ 6 rl p 0> UH O 4-1 4-1 -H C rH a) ca U 4J u u 0) O Ph 6 -3 u o o rH II E P 2! P. 4-> X 10 ^ TJ O 0) ^ rH P. 60 •H rH U co o 4-1 4-1 U O O CO PH T3 r^ 01 rP e > P "H z < — I 4-1 o 00 rH c a. tH rH 01 — P. X! 4-1 TD 2 o O -H CJ 01 o o SO CO (J aj a: o •H U a o o o o o cu X CJ •H U u o o o c a rH a co c en r^ H O o o o o o O o o c^ CM o CM m m CM o l"m CN CI o X CM CO i rJ o 4-1 3 a -:< UH HH O I CX 6 CO Q I X 3 CO CO Q o o o o o o 01 E c 4-1 u X O I cx cl Q I X 3 MH <4H O I a E d Q o r-. ^3" O o 00 CM o I p. ai S C o Ec u o C/j G en cu co 91 CO CO CJ •H c a x a OJ i x P CX O 00 00 i-H rH O O CM "J rH W X 1 CJ > M CO X CM M rH CJ X B 3 c i-H CO CO CJ CO rH P. CO P. c 4-1 (0 o O H cO TO •H cu C CO o CO 4J X3 u 00 00 o 4-1 CO 00 N o •H i-H X P. dS u >. 01 X p. TO CO 4-1 01 4J CO CO •H 0) TJ 3 3 > rH CO r-l u 01 u cx cfl •H •Jc

PAGE 57

worm were responsible for damage to 101 fruits, approximately 7.2% of the potential yield. Soft-rot, blossom end-rot, and cracking accounted for 75 fruits equivalent to ca, 5.3% of the estimated potential yield. Mechanical damage was of the order of 104 tomatoes or ca, 7.4% of the harvest (Tables 9 and 14). Only 1,128 tomatoes were classified as marketable of a total of 1,600. Ec onomic analysis The impact of the major mortality and cull factors, translated to monetary values per acre, is shown in Table 10. An amount of $3,283 was estimated as potential income per acre. Mole crickets, cutworms, and damp-off reduced the potential income by $328 during the Transplant period. Damp-off had an additional economic impact equivalent to $65 in the Bloom period. For the Fruit Set period the estimated potential income was $2,889. The economica losses due to Heliothis spp., pinworm, and hornworm was $208 per acre, $153 due to diseases and $213 caused by mechanical damage. After subtracting these values, an income of $2,314 per acre was estimated. This amount represents ca. /0% of the calculated potential of $3,283 (Table 10). Values for the cost/benefit analysis are shown in Table 15. Insecticide costs for 10 applications per acre were estimated at $150, thus, the net return of $2,164 represents 66% of the potential revenue per acre. Insect populations Insect infestations are shown in Tables 20 to 24. Methomyl plus dimethoate sprays were applied on a weekly schedule starting on March 18 until May 21. Aphid average was not significantly different from those of the Commercial or Check plots. On April 16, the maximum infestation was recorded (130 aphids per 100 plants), and the minimum (0 per plant) was observed on April 2 (Table 20).

PAGE 58

50 o i — i CJ 01 E S o u on CO 01 o 4-1 cfl E o a c CO u C 4J CJ [fl 0 E rJ c >N .a Cfl 0] c l-l CO O -a qj u c E H 01 CO >h CO u O CO CX H M a CrC T3 N en CO •rH 01 4-) (J C O 01 CO 4-1 \ o CO to 0) CO u CO o O CO -a rH CO N cfl 33 ex Eh J Ph CO •H 0) 4J M C U 0) CO u O O 3 0 |H rj CO v o •H H CJ C o cj co oo CN co co 01 A! CJ •rn 3 o CN -i oo CN 4-1 c cfl a, co a a M H m E in o 4J CJ in co CO E O 3 4-J 3 CJ CN CO CO co tin o i a E cfl P l .C 3 co CM CO CO CN CO c I a E cfl O cfl j o u I cx o o CN CO CN on o O i — 1 in vo in o co CO CO cfl CO E 4H M 0 X) 4-J O •H > i-H Cfl O 3 4J )H 01 o rH rH | CO •H CJ ta rH

PAGE 59

51 These data indicate that insecticides failed to provide 100% aphid control. No significant differences occurred between the three treatment strategies, when the leafminer average was considered (Table 21). Heliothis spp. eggs were detected for the first time on March 25. The maximum number of eggs found was 10 per 100 plants on May 7 and the highest number of larvae (4 per 100 plants) occurred on May 7 and 14 (Table 22). Pinworms were present from April 16 to May 14. Two larvae per 100 plants were found each time (Table 23). Hornworms appeared on the last two weeks and large larvae were observed consuming green fruits. Four larvae per 100 plants were recorded on March 21 (Table 24). Tables 25 and 26 show the number of arthropods collected by the pit-fall trap in the Commercial plot. During the nine sampling weeks, 116 individuals were captured. Of this amount, 56 (48%) were considered as beneficial, 32 (28%) as pest and 28 (24%) as scavengers. The beneficial arthropods were predators, parasites and pollinators, most of the pests were pathogen vectors insects and most of the scavengers were members of the Nitidulidae family. Check Plot N Life table. The life table shown in Table 11 indicates that there were three major mortality factors during the Transplant period. Loss of plants due to mole crickets, cutworms and damp-off were 3.0%, 8.0% and 1.0% respectively, which is equivalent to 26, 71 and 9 fruits lost per plot. These values are lower than those in the Management and Commercial plots because they are based on the yield obtained from 50 plants. The mortality factors mentioned before, reduced potential fruits by 106 per plot.

PAGE 60

52 u 0) CJ 0> ra i — I •H > CO o (3 •H u 0) 3 4J 0) •H U CD > co CJ o o hi o IH ra 4J cx o u o M H CO H ex C u cn IX 0) | o c 4J X CO U T3 O 0) ^ — i cx M o cj O M rH 0) CX Xi E 'H 01 p, o ^ C rH 0 (0 u H (1) P101 E 3 2 O C )-l T3 a n c u u O (0 -3 o 60 rH c a, •H > H i •H 01 i — ) CX -C T3 U O 3 iH O w M 01 a cx o CM 01 o •H H O c o o u G a CX 01 c 3 h H o o o o c o CM CO r^ CD 3: 3a 05 3 •H 3 0 (J CJ o CJ •H J= os TD 01 (0 3 ra XI Cj H to a > 3 .3 U CJ E 3 C a 3 XJ O ra 3 O T3 01 CO 3 43 0 rH ft M CJ ft 3 fH •ic

PAGE 61

53 No plants in the Bloom period suffered mortality, thus 88 plants were present and the potential yield was 776 tomatoes. During the Fruit Set period a severe disorder was noted, which caused a reduction of 38 plants per plot. Symptoms included stunting, loss of vigor and no growth, The plants were consequently considered as dead since they never recovered and although some were alive at the harvest time, no fruits were produced (Table 11). The Maturation period presented 50 plants with a potential production of 441 tomatoes per plot. Table 11 shows that the same three cull factors were operative, namely insects, diseases and mechanical injury. Heliothis spp., pinworms and hornworms caused loss of 105 tomatoes. Soft rot, blossom-end rot and cracking reduced the potential yield by an additional 93 tomatoes. Mechanical damage accounted for only 10 fruits per plot (Table 14). Economic analysis The potential fruit production value per acre was estimated at $922 (Table 12). This value was reduced $28 by mole crickets, $74 by cutworms and $9 by damp-off, during the Transplant period. Together, these values accounted for $111 per acre. A potential revenue of $811 was estimated for the Bloom period. No mortality factor was recorded in this period. The severe disorder visible during the Fruit Set period, caused a reduction estimated at $349 per acre. The economic loss due to Heliothis spp., pinworms and hornworms was $110 per acre, $97 due to diseases and $14 to mechanical damage, during the Maturation period (Table 12). After subtracting all losses due to damage by destructive factors, an income of $240 was obtained. This value represents ca. 26% of the estimated potential of $922 per acre.

PAGE 62

54 (1) Q ^? ^ O CO CNJ 1 — I 1 — \ (__) 1 CO I 1 Q CU — | ( ^ eg •H H [s] ca 4-1 o to .n -a 41 o 3 -h o U 5i CU in CM M o •H M u 0 o CN CJ> C ca — i a w G ca H o O o o o o o o o o o o o c o o C~ 1 (U c CJ o 1 4-J E rO ca o 3 cd o c C •H CJ 3 CJ C cn rH c S CO CJ o O o o o o o • • • • • rH rH r-i CTi —1 rH \D CO CO CO CO O o OA O • T3 H m C H ro 4H 4J E c C 4J o 3 cd a o c o o R CO IZ is H cn cu 4J CO g •rl 4J CO o o o O o 01 o o c o o • • • • c rH rH CM CM CM o rH i — 1 v£> 00 CO -T cd cn B 4-1 >-i cu TJ 4-1 o •H 3 > rH ca o 3 4-> CU o rH M CO •H CJ pq Pn S 5H

PAGE 63

55 Insect populations The fluctuation in insect populations was recorded weekly and the results are shown in Tables 20 to 24. No significant differences occurred between the three treatment strategies when aphid averages were considered. On April 16 the highest infestation of aphids was recorded (28 per 20 plants). By May 14 the aphid population had disappeared from the plot (Table 20) Leafminers showed a pattern similar to that previously mentioned. The maximum number (140 per 100 plants) was found on April 23. During the last two weeks no new leafminers were observed (Table 21). Heliothis spp. eggs were observed on March 25 and larvae (3 per 100 plants) on April 16. Eight larvae per 100 plants were observed on April 30, was the maximum number (Table 22), Pinworms appeared early on March 25. The population showed a relative stability during the season, but on April 30 and May 7, a level of 6 larvae per 100 plants was found (Table 23) Hornworms were observed on the last two sampling dates, May 14 and May 21 (Table 24). It is possible that the infestations would not be a hazard for a vigorously growing plant, but for a mature plant the damage occurs to the fruits, and therefore is intolerable The numbers of arthropods captured by the pit-fall trap are shown in Tables 25 and 26. From a total of 141 individuals collected, 92 (65%) were identified as beneficial, 23 (17%) as pests and the remainder 26 (18%) as scavengers.

PAGE 64

u OJ a a a •H C ra u -J £ •a c a m 0) in fl aj go •H "3 O -i On 4-1 H tO AJ 4-1 O O — I h a. u oj xi u u M o £ 6 o u c a e oj a co c -a CD K Q E to O •K M T3 cu in cu > u •a cu a to to Q e tO Q K M X) Oi u OJ > U tO ss o co m m -am fl fl CO vO CM 00 CM i — I vD CM CM CM CO CO ro cm m co m m rH (M H CO CM CM vD rH O r> r>r~ 1 I 1 1 l CO CO co CO H i — i CM CM 1 1 l 1 vO 1 CM o H EU ss CU M OJ CO o -J W c fl u C >. — E fl P. ft CO fl t-l OJ u OJ c X3 o a CO a G CO o O. cfl a. x> CO w

PAGE 65

M o -J •H c co C u QJ E T3 C n QJ to CO 0) CO •rH T3 4-1 u oj co c QJ 00 a E id T3 *a C to t) qj 4J CO a > M CO u 0) u H o M aj E E O 4-J a u E QJ CX n) vO os CO 4-1 4J O O rH CO H ^ CN t — 1 CN I — 1 vD O rH QJ £)fl O VO co CO ft! — i 1 — 1 CN i — I OS E rH Tn CN CTS vO C'J CN CO N o o o ~cf rH O ON iH rC > CN CN < vO co o vC OS o vO O CO O CN CO CN rH •H tH rH )H rQ cu cu K CN 0"N vD as in o -vT rH CO -K rH CO CO tH rH •H N CO Q rH 0) tO *1< •H CO — CO CN o en m m ON M Q (H H CO CO CN iH co rH rH r-. CN rH tH 00 C 1 E> CO CO vC as in as CN rH H 4H CN CO CN rH CO H 14H rH QJ 0 SC CO u U H DJ CU ^-s 3 to >H CO OJ 0) 4-1 CO X) iC vo CJ CO r4 vo VO vO 1) 0) o 01 r- r— vO vo r-s r-~ VD CO CO CO I CN I h r-^ i I rH C •H -H 4-1 1 1 m CN o 1 CO — Q TD CO CN r i rH CM CO VO 4-1 a 1 in I i i 1 1 i O -K I/I vO VO -.o vO H

PAGE 66

58 Table 15. Costs and benefits tomatoes* of alternative control methods for Method Number of applications Cost $ (Insecticides only) Benefit $/acre Net return $/acre 1975 Man. a g 6in en t 5 75 1,956.41 1,881.41 C n mm ptp t n 1 V..UJ11IUL 1. l_ J-dJ. i n 1 u i jU 1 ,48/ 26 1,337.26 < 11CL tv n u u 869 44 869.44 1976 rianagciuen u u 0 1,906.21 1,906.21 1 u 2,314 61 2,164.61 Check n u U 139 60 239. 60 Average Management 2.5 37.50 1,931.31 1,893.81 Commercial 10 150 1,900.93 1,750.93 Check 0 0 554.52 554.52 Based on Tables 2, 4, 6, 8, 10 and 12.

PAGE 67

59 CN o o o o o o rH cd CN o O > C_> < o o o o o o f~rH r ON CN M H N 0\ N j CO On O c CN CO o c 3 U Q C X m rrj u co 4-1 Xi c 00 0) !M ON OJ 00 14H rH 14H •H o o rH 4J CO c r-CO U •H l*H •H o oo 00 •H 00 CO CN 4J o c O 0) u CO 00 iH oo 0J CN S rH CO CO OJ r! o I i OJ < a B) t-i • OJ 4-1 > CO CO OJ 4-1 c E 0) 3 00 rH C O CO

PAGE 68

60 CN 5 CSI >, IS co rt cs a < CN < C < < < 3 o n4 o i-H fin < o cn o CN n co o ko >H cn co rt < •~ • oj 4-1 > CO co co 4-1 C 6 CD 3 00
PAGE 69

61

PAGE 70

a 0 id ux o p CN >, CO CO d a 3> S-i Q. < CN N H < < u < 3 o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o CN O CN CN O o o o o o o o o o o
PAGE 71

63 c o ^ co to CO 4-1 o> o co H is CO 2 o co M < co cj M ft < U ft < a. < ft CM M 3 o <2 c H Cx OA CO 00 CN rH o o o o o CO o o c o CM h cm co co o cc o CO CO CO \0 O IN h CO CO i— ( co m in cm o o o o o o o o o o CM 00 CM O CM O" CM O CM O c co m o cm m co CM CO a -3f CM O CM iH CO CO rH m m vo co -j CO o CO QJ SO CO >CJ > < lO CO H H O o o o o o H CM CO in CTJ cu | Q, Q Ti o CO c CO o u Q 1— I m 00 m aj (— M CD eg QJ 1( | t ) 1 rH TJ 4J 03 C CT3 £J CN •H i-H ^fi OJJ •H C/] tr co o CN r-> M 0) t-l nj CU 4 > CJ rH CD cd (N w CN Ml rrt -O f—\ Tj ^— > td u o QJ CJ

PAGE 72

c o CO CO CO J-> OJ o a o < CO cj ft < u ft < r4 a < S-J cc < in CN CO a o c rH ft co a w co n vO vO CO H sT o o o o o o o o o o 00 o o o o -d" CM VO CN jd m cn < vo vo a\ oo n rH cn cn m o o o o o o o o o o O O O CN o "> t — 1 4J c CN CO CJ lO •H rH 4-1 •H C 00 •H crj CO 00 • 4-1 rH O c QJ M CO CTJ O U OJ rH 4J 4-1 QJ rH CJ E vO CO CO V ^ 0) 4J CO CM TD CM CJ 3 O H i — 1 o a) 4-1 oo ctj CO CJ cu bC > CO j-j OJ 4-1 > CO CO 0) 4J Es QJ P oc rH C O CO U r4

PAGE 73

CO E rH O vO o o o O CN CN O O O O O O CN O O O CN O C CN o o o O O CN O CN o o o o o o o o o o cn o
PAGE 74

rH CN >n CO s rH CO r-. >> CO ^ • i-H D vD CO ON 1-t H ft < i U QJ O rH H a. CO ft 0 cm CO Jh C/J rH 0) ft ft l+H < o QJ x: M 03 CO rH rH P CO IH St ft < re T 1 i-H QJ ON u •H (H M ft H iH CO iH rH o CO pei 4J o H co rsl 4-1 o QJ rH rH Ph CO H o o o o o o o o o o O O O CN O O O CN o o CN O O CN O CN O O O O O O CN O O CN ,-N 3 3 O O O CN CN CN O O CN O CN CN o o o o CN O O CN CN i-H 3 rH rH O 3 i — I 3 i — 13 rH 3 rH CN 3 3 rH 3 3 CN 3 3 rH 3 rH 3 CN 3 3 CO 3 3 3 3 3 3 3 3 3 3 rH 3 CN 3 I — I 3 3 3 3 3 r-i CD O O C 3 3 3 3 3 3 3 3 3 3 3 3 rH rH rH rH 3 3 3 3 H CM CI ^ in c QJ 8 OJ to CC c re S rH CM CO < in re •H O >n QJ rH CN CO
PAGE 75

rH CN CM CO rH CN • 1 — 1 CO rH rH /— ) i f\ \J M r"~1 FA U a. en CN CN Li ,C O O cu 4-t id CO 4-1 M rH CN X H co CrH < Cg u 3 TJ C CM CO 53 H d. rH < O r — \ CM • — / CM CM CO U 00 (X rH 00 < 0) •a c m CO CM CM — l-l rH CO rH v / 53 dl cO > u CO rH 1 — 1 o CO P< 4-1 o H CO o o o o o CN CM CM CM CM O O O -vT O O O CM CM o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o a o o o o o o o o o o o o o o o o o o o o o o o o o o o o O 3 O O O o o o o o CM O CM O O CM O CM O O O O CM O O o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o O 3 O O O o o o o o o o o o o o o o o a o o o o o o o o o o o o o o o CM O CM O CM O 3 3 O O CM 3 CM 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 rH CM CO v-f U~| c
PAGE 76

68 to KJ i— f P< co i-J C U QJ -~ p: r* 0 u CJ 01 J3 U 13 c CO C) i — 1 rH CTi •H CO i-l 4-1 QJ •H C rH u QJ 0 r4 • 4—1 \-i QJ CO o 6 i — i P-H 6 o u 0) rH /-< r-H o 2 -H <-* -w> CO co 4-J I— 1 Q c c rH 4J 01 H a o e to H 0) e> c oo •H CO 0) li u >s c CJ 0) 01 c C OJ u QJ •H D5 u 3 3 a* co cm o QJ -a c a u 0 -H o o a. ^ e £ CO 4J CO r4 CO QJ C •H C 14H o CO 4-1 0) 3 >-J O 3 ^ 4-1 OC a. 3 CO O cj U X. a 4-> CO u CO 4-1 QJ o rH 4-1 i— I CO co e Mh O I 4J 4-1 •H 14-1 a, o m CM rO CO H a c E E 0 u cj •H U co QJ E CO c u u CO Cn X ~J 4-1 • H M H H 3 g CJ co IH U o 0 •> • | : CO n co co c 43 •H CO a i — i 01 rH CU i— I •H 00 I— 1 H co >^ cO c CO c CO 3 >s CO rH i-H 3 13 o 3 13 o 3 13 O rH 3 13 (0 >h X U on X) a ui -a M T3 QJ 3 CO •H > •H > a •H > 4= c cO c H M C T3 CJ 3 > >h > OJ > >H c 4-1 0 CJ o > 3 0 •H o •H QJ (0 •H 0) co •H oj o CO co •H 4J CO > 13 CO -a CO T3 0] 13 CO CO X CO 13 CO 13 a. CO H QJ CO C a C J3 C CO OJ a) OJ CJ c cO OJ "3 U 01 H 0 o •H o 0 •H o 01 in CO u CO H o CO c u tfl u >H co 3 3 H QJ 4-1 01 u 4J QJ o 4-J 0) 4J c4J (X 4-1 3J p. rH a CO sco In CO M T3 a c 3c CO' h c H ro aj a u a o 0) H co >H a u c QJ u H C u 5 •H 5 •H s 9 E u u u CJ 3 'J < o u 1h 0 4J CO XJ OJ 1-4 O CO co CN 00 cc a < 0) 10 -3 E •h c H— c 4-1 CO 4-1 13 CO 0) 0) t-i Cm CO, to O CN O CM O OJ M 3 hO C d Oh QJ CO TJ •H r4 U O 4J [fl 13 CO >H Cm r4 0) <4H XI rH -H o a Is CO co CO 3 3 4-J ro CJ co a. CO 4J 4-1 •H •H cx CJ •H P o CO E OJ E O CO u > Cco M 1! 0) E o O 1+4 4-J CO O > c o 3 o C CO CO ja QJ CJ o H a i-H PC >. u CO CO rJ QJ Cfl 13 H co O CJ >. rJ o 4J cd 13 OJ M Ph u-l CM cc >H OJ <4-l 13 rH -r-l O CX Z£ CO a CO CO co c 13 U CO 91 CO 13 •H CO o O >i rJ !h o 4-1 CO 13 QJ Ph U OJ U-l X! rH -H O D. 3 CO CJ CO •H Cfl c o rJ QJ M 3 QJ > cO CJ CO' on CM c-) C3^. CX QJ CO 0) CO ,£1 QJ CO u 3 X •H CO II 60 c a > co CJ CO C •H 0) rH rH ^ 4-J !h QJ CO OJ O rQ c CO cx 3 co to CO rH tfl 3 3 •H 3 3 CJ CO •H •H a. CO 4J rH ^ — \ c o rC CO rH 4-1 a CJ toCO CJ u 4-1 •H co 4-1 CO r-l CO 3 IH rH CJ
PAGE 77

69 to •H 4-1 qj C rH 01 o 4-1 U o o cn 4-1 z o rH rH a 4-1 O c H •H QJ CJ c QJ CJ M C U 0) a 3 o cr o QJ o r4 Ph c a •H u QJ E co c E TO u jr u u n I — 1 Q l-l a. ^, k-4. CJ G QJ o Q) Cj CJ QJ CJ 0 M 1— h 1^ QJ CJ CJ o QJ CJ Cj 114 a H > > •> "J CO H CO in G H co CO co CO •H 1 — 1 1 — 1 i — i — 1 — 1 1 (3 CO CJ TO CJ SI TO M id (H TO crj 4J 3 U 4_j 3 CO 3 TO G C -3 CO TJ CO TO -a a) X! QJ -a H •H H r-l •H rH H a H •H •H > > o > -a > TJ > T3 > -a •H ~ •H ~ TJ co H QJ •H 01 •H QJ •H CJ ~ QJ TJ CJ 0) TO TJ 4J 4H -3 4J 4-1 G v (J U TO ~3 C CO •H a G a < CO 01 cfl T3 •H J3 CO IH TO u Cfl 0) Ah J2 QJ CO rH l-l 4-1 CO QJ CJ QJ tO J3 CJ TO T3 •H 01 TO TO kl CO U M 0 u CO ~o QJ 1-1 Oh rH QJ 4-1 > QJ O QJ PS X> QJ TO •H C •H rH >, JS TO 4J CO U 0 CO 4-J 3 U U 01 -H > > co 01 fin T3 U QJ QJ TO a G r* J= a mh CO cO rH QJ PQ rH QJ M rH O 4-1 •H QJ rH Q) U ^3 co a TO -a CJ TJ TO u 01 TO TO3 •H Ih a jj TO rH W IH O 03 4-1 3 CJ )H QJ -H > > rJ CJ c o C4H TO QJ r-" co TO CO a rH c co w co J3 rH G 3 3 3 4-1 QJ U co (H C co TJ c c l|H 01 OJ CO o rH o H •H -o -3 •H •H G rH E Ih )H o 4J 4J •H a TO 10 o 3 •H •H TO a r4 •rH G X PC PX co c u w CJ CJ TO -a 0J — CO CJ co TO u TO T3 H T3 TO U CJ CO "3 •H TOJ TO

PAGE 78

70 o co 4-J O H cO D. 0 t C H •H / — S QJ U c 01 u u c u QJ 3 3 u cr u rH > u c o CO H X X CO CO 00 bO H a — j 1 — 1 3 c 3 c CO o rH nj rH T— | CO 1 — | Q Q Q Q 3 M a u lH M M co M X; X! J3 CtJ X CO CO 13 c3 x CTJ X cfl H 4J a (L c •rl 11 C a) c •H QJ c CJ •u OJ > a o > O o > 0 CO CO •H X co 13 05 H 13 co X) co •H -J co XJ Xi •X3 oj re OJ nj 13 OJ CO QJ re XI 01 10 OJ x QJ X C *J QJ 4J QJ C 4J 01 4-1 QJ C HI QJ HI 0 J o •H u co a Cfl •H a co o co •H a 01 a M CJ u 0) QJ QJ QJ QJ QJ U OJ U 4J rH x rH a u rH a rH HI rH (X rH i-H to rH c rH 0 1 — 1 c rH O 05 1— 1 0 H QJ rH 0) £ 0 M o o u O U 0 c X o X o CJ CJ a CJ u o 1 u cj CJ HI CJ HI M O HJ Cfl •a QJ 1-4 X o CN < CO a CO CO CJ •H O rH H (-1 C o CO o •H — \ X •H rH a 00 >, M QJ o •H CO 01 Lh u QJ H CO X o O CJ 3 ^— PL) E X CJ 01 CTJ cfl "3 X) •H •H CJ 0) •H CI ElO e o X X u o HI Cfl X CJ u X CO c3 XI •H > CJ rJ QJ r^ O 4J CO X QJ v-< X CO X o •H HI CO u 4-J O QJ 0) X 13 rH X H •H CO (X 4-1 rH c CO K CJ • X X X X CO CO cfl Cfl o X a cfl c CJ CJ cfl 13 H CO C X D. Cfl c X 0 4-1 CO 13 QJ X a oj a x: w a. ca c/j S x cx co CJ re "3 •H CJ CJ X a w u o cfl c c X CO 13 •H CJ •H rH QJ CO 0) X X X a. 0) n QJ Cfl H & UJ Q) Cfl X •H 4-J CJ Vj o tJ rj 13 QJ X OJ rH •H ^ 4-1 rH C/J 14-1 cfl X QJ Cfl u •H > QJ S-i QJ X X rJ c -3 '3 u X P J re H re CO X •H X CO u X a c c c r-I CJ •H X rH co X o X CO cr. 4-1 CO C 3 < -H CJ •H M X c X re C H E Cj cj: u re x •H a •h e 'H o x

PAGE 79

71 •a a) p c P o o LO CM Xi cd H ca •H 4-J QJ C rH aj o O o z 4-J o H rH cd a 4J o c H •H ai o c 0) o l-l c l-l 0 qj OT H 3 H E rH O rH CX (-1 M C 0 C cfl rC o r4 H p u c 4-1 a 0 o QJ OT 13 OT a M c a a 01 cd m o •rH Oi 4-) 0) 4J 3 u OT u Cfl CJ QJ QJ Qj x: 1 — 1 H a rH ex rH 4J H o rH o i-H C O o t-i O cu u o u u u OT QJ Cx r4 ai a p. o 14-| rd OJ rJ CO i-H CO cd X r4 a. OJ o 4-I CJ •H / — s O 4-1 r4 a •J Oi c H rH 04 M Cd cfl g u M -J cd -a 'H OJ Cd CJ •1 U OT QJ Ph OT CX a o a OT a en aj u CO • rH C o TJ Cfl QJ CO 4-J QJ O W 0) -I a, rH o o r4 u a Cfl o o CM a rH rH H rH O o CM o o o r4 TJ 01 o > QJ rQ l-l 0£ o XJ o CX 4J H 4-J Cfl QJ P u •n x: E CO o o cd CJ CTJ cx cx CX CO rH ex o — pq < OT w < CJ 23 0) Qj QJ cd QJ cd CO •a co TJ -a H TJ •H •H rH •H rH rH QJ QJ rH rH E cd cu QJ 0 rQ T) TJ OT cO CO cfl >, Vj CJ CJ l-l m •H •H Jp CJ QJ u U C/3 p c •H •H >^ > H rH Xcd cd Cj c QJ p o c "3 OT "3 OT QJ CO QJ Cd 4-1 u XI QJ CJ OT CJ CO u O rH CX iH CX H o H c o u C rJ CJ CJ u CJ 4J Cfl OJ CX Xj OJ cx P-, o X Cfl OT CO >-. CJ Qj CO -a •H "3 •H U (J < •H OT cd u cfl fX c o s 3 a c X a p c rH cd E cd cx c cx < OT 'QJ CO ~ •H R C i QJ C Xd CJ

PAGE 80

72 c v o u 4-1 c QJ 4-1 c o Cfl 4-1 O t-H cfl ft 0 L c H •H 01 •> o c QJ u u c u oi 3 3 o cr u 01 o Fr c o s 6 0 u 01 H (J c 0) co •h c cj w J3 u u CJ u 4-J 0) ft Cfl O • u • Cj M c •H C CJ 4J o C o 3 Cfl Cfl c •H Cfl •H en -a V4 a •H CJ CO i — i •H 'H (D >> J3 CJ 0) cfl g Cfl QJ — i 4J 3 U t-i CO X) C a a cd Cfl c a H c — < H •H o tH 3 CJ c H 0 c > i~ o o Cfl H -o T3 u 13 Cfl T3 Cfl T3 CJ oi cfl 0) u CJ cfl 0) CO 01 4-1 01 c 4-1 4J 4-) CJ 4-1 CJ 4J cj Cfl •H CJ 3 a O u Cfl a Cfl CJ O 11 QJ o D CJ CJ ai 1 — 1 cx 4-) H Cfl iH H a i — t a H 14-1 H o Cfl H Cfl H i — 1 H 0 rH 0 H rH o c£ & 01 O a) O M O o Cfl cj u cj Cfl a -3 U CJ o CJ CJ J3 ca cd u cfl CX CO CJ o s: 4-1 01 s c 3 a> to CJ M P 01 > CO a u-l 3 4J CJ > CJ 4-J > ai c o > CO rJ u CO cfl CO l-l CO PL, >H O 4J cd TJ 01 1-1 CX l-l o 4J cfl -3 01 M Cx 0 4-1 cfl -3 a u ft H C o a en QJ CO 4J 0) O CO 01 i — i ex o u CJ 0 0) 00 C o > CO a CO •H u 01 3 QJ CJ T3 CJ X) QJ Ad o •H t-H C i — 1 3 H •H CJ TJ 4-J 3 4J 3 4-J rH CO 1 — 1 CJ O CJ o 01 u u 0 CJ M CJ X CD c S3 w .3 u < Cfl 3 Cfl J3 3 4-J — < cfl CO Cfl 3 Cfl c 4-J 3 4J CJ M a ,3 Cfl CO rH o CO X 0) 3 'CJ •H 13 3 rH CJ 4J H 0 E 3 •H c 3 Cfl H Cfl •C CO CX CO cx •H a. Cfl XI E*. 4-1 ft cx JO cx 3 ft a 3 CO C < Cfl u Cfl < CO ex Cfl c/i <; 3 H CO • 01 c o T3 Cfl 0) CO 4-1 01 CJ Cfl 01 t-H ft H O -i CJ o U CJ Cfl cfl M 3 ex 3 O § 3 : cx CO w Cfl e 3 Cx CJ 3 -a 3 QJ 3 -a 'H 3 O •H X) •H CG QJ 3 TJ •H 3 G O 3 C4 m CJ 3 T3 •H H 3 -3 4J 3 3 CJ CJ 3 T3 •H rC 3 M 3 U QJ 3 -3 •H 3 l-l cfl CJ 01 3 -3 •H CJ 3 Cfl -3 H 3 C E 3 3 3 43 CJ 3

PAGE 81

73 T3 QJ 3 C c o u CM Cd H CO •H 4-1 O) C rH a) o 4-1 r-l O ft o 4-1 r=5 o rH rH a ta 4J c o •H H s 01 u r-l c 1-1 a) a s u c o 01 o M rH c o a) e e E co o c u cj H >4-4 H 4-1 0> C E (1) crj •H C CJ CO •H E id 4= U rC CJ 0. 0 M cj -J ro 1 j CB OJ X a 4-1 CJ C CD o co r-l CO O 01 CJ CO CO J ft rO OJ rQ rH l-l 4-1 co 0> u 0) CO rQ CO co •H 3 co WJ C co :j X. E cx C o rC c rC 3 4-1 rH 0 c -M M o C pq QJ a X •H OJ CO rQ CO S-J C3 CJ co Ob o L4 CJ c in in in c a •H •H •H >, E te rl rl rl te C cd ca cd re a •rl rH on o> on OJ on 01 on rH c 0 X 13 co ID co XI co X CO XI co OJ OJ nj QJ re QJ re V re QJ CO 4-1 u OJ 4J QJ IJ a 4-1 CJ % CJ E d 60 rH o ft E QJ cd X 4-1 u cd X •H M H CO a. H OJ a a, o rC CM cd 01 rJ QJ cd X 01 X cd CJ •H CJ CO a o •H CJ •H 4-1 c at > x < rH CH H ft QJ cd X •H P. o r-l o rH JS u CO O •H CJ C CJ > X < X H c U r-l XI 0) C 01 < rQ CO a rH CO co J3 Qj a 4-1 u cd C3 CJ rH C •H 0) 0) c ft l-l re a aX Cc rH ft H ft c ft CO IB co < co QJ a x •H c CJ l-i X a < CO QJ o 01 01 o rQ CO 0) i—3 Si QJ re x 01 E o CO >. l-l l-l o u 4-1 01 0 4-1 01 cn > CO CO o 01 l-l QJ cx ft o rJ -C CU M-l U CO W 0) QJ re x ai X re cj •H CJ U CO • 0) c o T3 05 0) co 4-1 01 CO CMj H 13 H re W ft c_ CO 00 QJ co H c re 01 o H 4-1 l-l ~ co I4H s CJ c •H r-l •H VCJ o 1+4 ft 'CJ co 4-1 U ft re re CO o CO S CM Eh QJ CO X 3 o •H 14-1 U c ft CO rH ft l-l O O U U CJ u o 4-1 CO X QJ •h Ph

PAGE 82

-a aj 3 c a £ e o u •H 4J CU C — I a) o •u S-i o ft CO 0 4-1 z 0 iH rH ex m 4-1 c o •H H N OJ cj c >, o u c u a) u ou o 1-4 Ch c 0 (U 1 E e o C u •H 4-1 QJ c e 0) n3 H cj CO X! u U M (0 • 0) c o -a ca 01 CO 4-1 0) CJ CO rH a, < — i o o >n u o 1-4 v M c 01 > td cj w 00 C •H 0) iH rH X 4J (-4 01 cfl 0) a ,o a co cfl o Cfl 3 u •H 4-J a >, M U cfl • 0) C o td cn 01 cfl 4-1 01 o CO OJ rH CL -H O O 1-4 U U Cfl a) X U •H ft < rH M cfl • o) c o -a cn 0) cfl 4J 0) O Cfl Ol rH D, rH O o u u u 1-1 o 4J Cfl -a 0) IH ft c •H rH C o T3 Cfl 0) cfl 4-J OJ o cn 01 h a. rH O o u u o Cfl cfl U cfl IH Cfl • 01 C o XI Cfl 0) cfl 4-J QJ cj cfl 0) rH O. rH O O U U CJ r-l c 4-J ~ u ft H cfl • 0) C o T3 Cfl OJ cfl 4-1 0) CJ Cfl 0) rH a, rH O o u u u CO OJ Ph Cfl • QJ C o T3 Cfl 01 cfl 4-1 01 cj cn 01 re D, rH ft 01 ^* rH Cfl cfl H DJ o 11 U Cfl Cfl •H N 0J •H 3 Cfl rH H rH N r-l a rH ft 0 £ CU 0 ft CJ ft CO cn Cfl o u o 1-4 CJ Cfl 01 ft cfl s-4 Cfl Cfl 0) 3 13 rH 3 o OJ Cfl OJ rO CJ Cfl >i ft •H ft £ ft X ft a. ft CJ ft o cn W cn < cn H C o •a cn 0) cfl 4-> 01 o cn 01 rH ft rH O O U U CJ Cfl 01 IX U 13 U 13 1-4 •H H •H H H OJ o H CJ OJ CJ rH CJ 4-J H rH i— 1 J^ CJ ft rH a 01 ft Cfl 4-J cfl 4J CJ rC Cfl 0 rC Cfl •H OJ 4J , U CJ

PAGE 83

75 Table 26. Total numbers of arthropods collected by pit-fall traps in Management (M) Commercial (C) and Check (Ch) plots of tomatoes during nine sampling weeks. Gainesville, Fla. 1976. Pests* Beneficial** Scavengers*** M C Ch M C Ch M C Ch 35 32 23 96 56 92 34 28 26 *Include virus vector insects and some phytophagous. *Most individuals were ants. *Most individuals were of the Nitidulidae family.

PAGE 84

76 Table 27. Estimated dollar loss by major mortality factors on tomatoes 1975 (Management plot I) FRUITS Growth Potential* Loss p er iod ^ / ?/acre Hazard % Loss** $/acre Transplant 2,880 Mole crickets 2.0 57.60 Cutworms 3.0 86.40 • Damp -off 1.0 28.80 Sub-total 6.0 172.80 Bloom 2,707.20 Damp-off 2.0 54.14 Fruit Set 2,653.06 None 0.0 0.00 Maturation 2,653.06 Tns er t s • j JUj IU Diseases 2.3 < 61.02 Mechanical 6.2 164.48 Sub-total 20.0 530.60 Harvest 2,122.46 Yield 2,122.46 Total 757.54 1 Cost values based on estimates of Brooke, 1976. *Based on the potential maximum yield over two seasons. **Values based on percent of loss of respective treatment strategy (Table 1).

PAGE 85

77 Table 28. Estimated dollar 1975 (Commercial loss by major mortality plot II). 1 factors on tomatoes FRUITS Growth period Potential* $/acre Hazard ; I Loss** Loss $/acre Transplant 2,880 Mole crickets 2.0 57.60 Cutworms 4.0 115.20 Damp-off 2.0 57.60 Sub-total 8.0 230.40 Bloom 2,649.60 Damp-off 1.0 26.49 Fruit Set 2,623.11 Damp-off 1.0 26.23 Mpf"iiT"3 f" inn I id L U I a L. lull Insects 9.0 233.72 Diseases 1.6 41.55 Mechanical 6.5 168.79 Sub-total 17.1 444.06 Harvest 2,152.82 Yield 2,152.82 Total 727.18 Cost values based on estimates of Brooke, 1976. Based on the potential maximum yield over two seasons. ** Values based on percent of loss of respective treatment strategy (Table 3).

PAGE 86

78 Table 29. Estimated dollar loss by major mortality factors on tomatoes 1975 (Check plot 111)1 FRUITS Growth Potential* Loss period $/acre Hazard % Loss** $/acre Transplant 2,880 Mole crickets 2.0 86.40 Cutworms 2.0 57.60 Damp-off 3.0 86.40 Sub-total 7.0 230.40 Bloom 2,649.60 Damp-off 1.0 26.50 Fruit Set 2,623.10 Damp -off 1.0 26.23 Maturation 2,596.87 Insects 20.0 519.37 Diseases 5.1 132.44 Mechanical 7.0 181.78 Sub-total 32.1 833.59 Harvest 1,763.28 Yield 1,763.28 Total 1,116.72 1 Cost values based on estimates of Brooke, 1976. *Based on the best yield over two year seasons. **Values based on percent of loss of respective treatment strat (Table 5).

PAGE 87

79 Table 30. Estimated dollar loss 1976 (Management plot by major mortality I) • factors on tomatoes, FRUITS Growth period Potential* $/acre Hazard J I Loss** Loss $/acre Transplant 2,880 Mo 1 p pri plr pf c 1 1U i — L L 1L 1\L LO 8 0 ?3f) 4fl Oil f" WOTTTI c. 3.0 86 4f) T^aTiTn — n "F f ij'dilljJ U i J. ?8 8f) Sub-total 12.0 345.60 Bloom 2,534.40 None 0.0 0.00 Fruit Set 2,534.40 None 0.0 0.00 Maturation 2,534.40 Insects 10.6 268.64 Diseases 8.8 223.02 Mechanical 8.3 210.35 Sub-total 27.7 702.01 Harvest 1,832.39 Yield 1,832.39 Total 1,047.61 Cost values based on estimates of Brooke, 1976. Based on the potential maximum yield over two seasons. ** Values based on percent of loss of respective treatment strategy (Table 7).

PAGE 88

80 Table 31. Estimated dollar 1976 (Commercial loss by major mortality plot II). 1 factors on tomatoes FRUITS Growth period Potential* $/acre Hazard I Loss** Loss $/acre Transplant 2,880 Mole crickets 4.0 115.20 Cutworms 2.0 57.60 Damp-off 4.0 115.20 Sub-total 10.0 288.00 Bloom 2,592.00 Damp -off 2.0 51.84 Fruit Set 2,540.16 None 0.0 0.00 Maturation 2,540.16 Insects 7.2 182.89 Diseases 5.3 134.63 Mechanical 7.4 187.97 Sub-total 19.9 505.49 Harvest 2,034.67 Yield 2,034.67 Total 845.33 1 Cost values based on estimates of Brooke, 1976. Based on the potential maximum yield over two seasons. Values based on percent of loss of respective treatment strategy (Table 9).

PAGE 89

81 Table 32. Estimated dollar 1976 (Check plot loss by major mor III). 1 tality factors on tomatoes, Growth period Potential* $/acre Hazard % Loss** Loss $/acre Transplant 2,880 Mole crickets 3.0 86.40 Cutworms 8.0 230.40 Damp-off 1.0 28.80 Sub-total 12.0 345.60 Bloom 2,534.40 None 0.0 0.00 Fruit Set 2,534.40 Unknown 38.0 963.07 Maturation 1,571.33 Insects 23.2 364.55 Diseases 21.0 314.26 Mechanical 1. 1 "5 /. C "7 34.5/ Sub-total 46.4 713.38 Harvest 857.95 Yield 857. Total 2,022.05 1 Cost values based on estimates of Brooke, 1976. Based on the potential maximum yield over two seasons. Values based on percent of loss of respective treatment strategy (Table 11).

PAGE 90

82 Table 33. Costs and^benef its of alternative control methods for tomatoes. Strategy Number of applications Costs $ (Insecticides only) Benefit $/acre Net return $/acre 1975 Management Commercial Check 5 10 0 75 150 0 2,122.46 2,152.82 1,763.28 2,047.46 2,002.82 1,763.28 1976 Management Commercial Check 0 10 0 0 150 0 1,832.39 2,034.67 857.95 1,832.39 1,884.67 857.95 Average Management Commercial Check 2.5 10 0 37.5 150 0 1,977.45 2,093.75 1,310.61 1,939.95 1,943.75 1,310.61 1 Based on the potential maximum yield over two seasons (Tables 27 to 32).

PAGE 91

DISCUSSION This study conducted over a two year period, is the first attempt to utilize a modified crop life table to provide a suitable rationale basis for management of tomato pests or for a multiple fruits bearing crop. The results of this study indicate that life-table analyses are suitable for tomatoes, permitting not only an insight into the time and action of the different mortality and cull factors, but a direct cost accounting of crop and fruit loss. The information provided by crop life tables can be used to improve decisions and reduce uncertainty present in some pest management programs. Transplant Period The life table format illustrates how early in the season pests often ignored can be responsible for significant losses in potential tomato yield. As soon as the plants are set in the field, mole crickets, cutworms, and damp-off become serious hazards. Although only direct effect is included in the table, other indirect effects are involved, namely costs of new seedlings and labor of checking and replanting, fertilizer and irrigation, and loss of revenue from the empty space. A rational basis for the cultural practices of fumigation and mulching could be obtained through the life table approach when these cultural practices are instituted, as in tomato production in South Florida. 83

PAGE 92

84 Although the two Experiments were planted in different areas in 1975 and 1976, mole crickets, cutworms, and damp'-off caused damage on both fields. This fact indicates that these pests are ubiquitous and cover an extension of land. The level of infestation, however, is likely to differ in other areas of Florida. Even in the same field, the damage was never uniform in the plots. During 1975, cutworms were the most important mortality factor acting throughout the Transplant period of tomato growth. The average of the three plots was 3.0% of plants killed, equivalent to 192 plants lost based on 6,400 seedlings per acre. The economic impact is in direct relation to the damage. The average loss of revenue for the three strategies was $62, but the reduction in each was different: higher in the Management ($80) and Commercial ($79) strategies, and lower ($42) in the Check. These differences are present, due to the fact that the estimated potential revenue for each approach was different. In the Management this was $2,661, in the Commercial it was $1,993, and in the Check $1,382. When the maximum yield over the two seasons is used to estimate potential revenue, it is equal to $2,880. Based on this figure a more realistic economic impact can be obtained. Each plant lost (1.0%) is equivalent to $29 (Tables 27 to 32). Based on this point of view, 3.0% of plants killed would represent an economic impact of $87 per acre. The 1976 gross dollar potential for tomato fruits was well above 1975 values on Management and Commercial approaches. All mortality factors increased the extent of damage and reduced dollar revenue in 1976.

PAGE 93

85 Cutworms were the second important mortality factor during the Transplant period in 1976, The average damage of the three plots was 4.3%, 1.3% higher than that in 1975. Plant loss was 277 and the average economic impact was $76 per acre, approximately $14 higher than that for 1975. The economic impact per acre differed in each strategy, depending on the potential revenue per acre. High differences were observed between the Check approach during 1975 and 1976, with respect to damage caused by cutworms. The difference is due, in part, to the differences in the potential dollars revenue, $1,382 in 1975 and $922 in 1976. The second most important mortality factor was mole crickets, during the first period in 1975. The pest caused, on the average, loss of 2.3% plants per plot, equivalent to 147 per acre. Again, this damage translated to economic values per acre, shows variation depending on the estimated potential revenue. Thus, for Management was $54, for Commercial $40 and for Check $42, but the average was $46 per acre. This value was Ca. 26% lower than that occasioned by cutworms. In contrast with the abundance of mole crickets in 1975, in 1976 the infestation was higher and the pest was the most important mortality factor during the Transplant period. They destroyed 5.0% of the plants per plot, on the average, approximately 320 per acre. The economic impact was $133 per acre, almost three times higher than the value for 1975 for the same growth period. Damp-off was the third mortality factor during the Transplant period in both experiments, 1975 and 1976. The average of plants lost was 2.0%, but the economic impact was $36 for 1975 and $57 for 1976 per acre, on the average.

PAGE 94

86 During the Transplant period of tomato development the mortality factors, together, accounted for reduction of revenue of $144 in 1975 and $266 in 1976 per acre. This fact indicates that the damage was higher in 1976 and that the economic impact depends not only on the level of pest infestation but on the potential revenue of the crop, such as it appears on Tables 27 to 32, and on the season. Bloom Period During the Bloom period of development, plants were not affected as severely as during the Transplant period by soil pests since the growth had started, the stem increased in diameter and the roots were firmly established. But, some plants were yet in a susceptible stage to disease agents persistent in the soil. This fact and favorable weather conditions permitted damp-off damage during the Bloom period in 1975 and 1976. The economic impact, per acre, in the first experiment averaged $29, in the second experiment $22, although the first had twice the damage of the second one in terms of numbers of plants damaged. Fruit Set Period During the Fruit Set period, plants suffered relatively lower damage in both Experiments with exception of the loss occurred in the Check plot during 1976. One disorder caused by deficiency or low availability of Ca, in the soil, diminished 38.0% of the surviving plants. The economic impact, per acre, reached $349, This was the most 1

PAGE 95

87 important mortality factor recorded during the Fruit period in both experiments. Soil pests caused damage only in the Commercial and Check plots in 1975; the economic impact per acre was $16. Maturation Period The effect of cull factors on fruit quality and quantity was more pronounced at the harvest time. No attempt was made to determine the effect of leafminers on production, since the infestations were relatively low and also because Levins et al. (1975) report that leafminers in low populations do not directly affect yield. Insects, diseases and mechanical damage were the cull factors detected at the time of harvest. Mechanical and disease damage were caused by the same factors during both Experiments, but insect species attacking fruits varied from one year to the other. Heliothis spp. and armyworms were responsible for all fruit culled due to insect damage in 1975. The Commercial plot received 10 sprays with methomyl plus dimethoate, however fruitworms caused 9.10% of cull fruits, equivalent to $162 less per acre. The Management plot received 5 sprays, but besides Heliothis spp,, armyworms were present. Together they caused a loss of $282 per acre and damaged 11.5% of the fruits. In the Check plot, Heliothis spp. injured 20.0% of the fruits and reduced the revenue in $249 per acre. The differences within percentages of damage and economic impact, stressed the fact that the potential revenue (high or low value crop), and the number of fruits damaged would have great influence on the calculated reduction of dollars per acre. The number of fruit damaged in the Management plot were equal to those damage in the Check plot, but the damage in the first

PAGE 96

W3 S 1 1 • 5 fa while in the second it was 20.0%. Due to the lack of uniformity with respect to the damage caused by Heliothis spp., the percentages of damage during 1975 support those given by Wilcox (1956), Middlekauff et al (1963), Harding (1971) and Oatman and Planter (1971). The results do not support those given by Shorey and Hall (1963), Creighton e_t al. (1971), Creighton e_t al. (1973) and Creighton and McFadden (1976), especially in relation with the damage caused to the Check plot. During 1976, Heliothis spp., pinworms and hornworms were responsible for all the fruit damage caused by insects. No sprays were applied on the Management plot, but the Commercial plot was sprayed 10 times in 1976. Regardless of chemical applications, fruits were also injured in the Commercial plot during the Experiment 2 1976. Insects damaged 7.2% of the fruits, 1.8% less than that of the Experiment 1 1975, but the economic impact was $208 per acre, $45 higher than that of 1975. In 1976, insects damaged 10.6% of the fruits of the Management plot and reduced the income by $278. The values are not different from those of the same strategy in 1975, although in 1976 the damage was caused by three species of insects meanwhile in 1975 only one species was recorded. This fact suggests that the damage caused by different species, is not accumulative and that competition or, other factors, affect the damage severity. These results indicate that the damage caused by different factors may be high in terms of number percent, but depending on the crop value, the economic impact is variable. The damage varies from one season to the other and the same mortality factors did not act with the

PAGE 97

same intensity. The final effect is a result of the forces interacting in the plant system. The replication of life table in time and space is a sound idea tending to obtain better knowledge of the constructive and destructive forces that are active in an agroecosystem. Due to the complexity of agroecosystems a team approach to pest management is advisable. Insect Populations During the Experiment 1 1975, the maximum infestation of Heliothis spp. was 6 per 100 plants in the Management plot. This pest plus Spodoptera spp. damaged 11.5% of the potential fruits. In 1976 in the same plot, there were three species of insects: Heliothis spp. with a maximum infestation of 4 larvae per 100 plants, pinworm with 4 larvae per 100 plants and hornworm with 4 larvae per 100 plants, however, the damage 9,0% of fruits was lower than that in 1975. This fact suggests that there is not a direct relationship between pest numbers and fruit damage and also that the damage is not accumulative. Heliothis spp,, in 1975, plus pinworm and hornworm during 1976, caused 9.0% and 7.2% of cull fruits, respectively, in despite of 10 insecticide applications to the Commercial plot. It is possible that the time of applications was inappropriate since older and larger larvae are more difficult to kill. The tobacco hornworm Manduca sexta (Joh.) was presented in the Experiment 2 1976. The infestation was generalized on the three plots and it was observed feeding on green mature fruits and accounted for the loss of them, became a cull factor. The infestations occurred in the

PAGE 98

90 last two weeks of sampling and near the time of harvest. So, this pest could be one hazard for the fruits when the plants have finished their physiological growth. During 1976, infestations of aphids were relatively high (5,240 per 100 plants) in the Management plot compared to the other plots, the same year and the previous year. No insecticide was applied because there are no data on the economic impact caused by this insect to tomato yield. High numbers of aphids were observed on one outside row throughout the sampling interval, suggesting a particular spatial distribution. The misunderstanding of this fact could result in one unnecessary application of insecticide. The maximum average of aphids (1,048) per plot was found on May 7, and after this date the population declined drastically to 178 per plot on May 21, A sample taken on May 21 was analyzed and a Fusarium spp. was identified. There is no previous report on this pathogen attacking aphids, From a total number of individuals captured by the pit-fall trap, in the Management and Check plots, 59% and 65% were identified as beneficial, respectively, meanwhile in the Commercial plot, only 48% were beneficial. Insecticides reduced the number of beneficial individuals, in Commercial plot 11% and 17% when compared with those of Management and Check plots. No relation was found between Arthropods captured by the pit-fall trap and pests attacking tomato plants.

PAGE 99

91 Economic Analysis The net return per acre, that is the benefit obtained minus the cost of insecticides applied, was different for the three strategies based on the value of fruits actually harvested. During Experiment 1, the Management strategy showed higher ($1,881) net return, but during Experiment 2, the Commercial was the best strategy. However, considering the average, the Management strategy had higher net return ($1,894) than Commercial one ($1,751) in the two years. Based on the potential maximum yield over two seasons, Management and Commercial strategy showed no net return difference. Consequently, the two strategies appear to be equally effective for management of tomato pests.

PAGE 100

CONCLUSION The purpose of this research was to construct a crop life table for tomato production based on quantitative crop losses caused by destructive pests and to evaluate the utility of the table as an approach to identify determinant factors in the management of tomato pests. Experiments were done over a two year period, two crop seasons, in Gainesville, Florida, The results of this study indicate that life table analysis is useful in identifying and evaluating pests and strategies suitable for tomato production. The information provided by crop and fruit life tables could be used to improve pest management programs reducing uncertainty and increasing benefits throughout a sound manipulation of resources available. The format of life table permits not only an insight into the effects of different mortality factors, but a direct accounting of crop and fruit losses. Crop life tables stress a multifactor approach in relation to crop mortality and fruit loss. The destructive mortality factors acting on tomato were cutworms, mole crickets, Heliothis spp. Keiferia lycopersi cella (Walsh.), Manduca sexta (Joh.), Spodoptera spp., damp-off, softrot (Bacteria), blossom-end rot and cracking (nutritional and physiological disorders) Excessive mechanical damage of fruit was caused by cultural practices made by hand. Also, a soil disorder accounted for considerable crop mortality, especially in the Check plot during the 1976 crop season. 92

PAGE 101

93 Cutworms ( Feltia spp.), the most important mortality factor in 1975, destroyed on the average for the three plots, 3.0% of the plants during the Transplant period. In 1976 and during the same growth period, this pest destroyed 4.3% of the plants, but was the second largest mortality factor. The average estimated economic loss per acre caused by cutworms was $63 in 1975 and $77 in 1976. Mole crickets ( Scapteriscus spp .) were the second greatest mortality factor during the Transplant period in 1975, accounting for and average 2.3% of plants lost, but during 1976, this insect was the major mortality factor and accounted for 5.0% of the crop loss. These percentages are equivalent to an average estimated revenue reduction per acre of $46 in 1975 and $133 in 1976. Mortality caused by damp-off was similar during both Experiments for the Transplant period. An average of 2.0% of the plants were lost. The average potential economic loss per acre was $36 for the first year and $57 for the second. Collectively, cutworms, mole crickets and damp-off, during the Transplant period, affected 7.0% and 11.0% of the plants and reduced potential income by $144 and $266 per acre, in 1975 and 1976 respectively, on average for the three plots. Damp-off also affected 1.3% of the plants in the Bloom period on the Commercial plot during Experiment 1 and 2.0% on the Commercial plot during Experiment 2. The economic impact per acre in 1975 averaged $29, in 1976, $22. The effect of cull factors on quality was expressed and evaluated at harvest. In both Experiments, mechanical and disease injury were caused by the same factors, but the insect species and intensity varied

PAGE 102

94 for the two seasons, In 1975, the Management plot was sprayed 5 times with methomyl plus dimethoate to control Heliothis zea Boddie and Spodoptera spp. populations. Still these insects damaged 11,5% of fruits, equivalent to $282 loss per acre. The cost/benefit ratio was 1/7,5. In 1976, this plot was not sprayed with insecticides. The main cull factors were Heliothis spp., pinworms and hornworms, which caused damage to 10.5% of the fruit and an estimated reduction of $278 per acre. The Commercial plots were sprayed 10 times in 1975 and 1976 with methomyl plus dimethoate. However, during the first Experiment, Heliothis spp. caused 9.0% of cull fruits and an economic impact of $163 per acre. In 1976, Heliothis spp., pinworms and hornworms damage fruit on average 7.2%, that is $208 per acre. The Check plot was not sprayed with insecticides. In 1975, Heliothis spp. injured 20.0% of the fruits for a loss value of $249 per acre. In 1976, Heliothis spp., pinworms and hornworms together damaged 23.3% of the fruits per plot, equivalent to an economic impact of $110 per acre. This low economic value was due to excessive plant loss caused by a soil disorder, thus does not accurately reflect 1976 conditions, During 1975, cull fruits due to disease and mechanical injury were of the following economic order per acre: Management strategy, $57 and $151; Commercial $29 and $116; and Check, $64 and $62, respectively. But in 1976, the values were higher: Management strategy, $232 and $220; Commercial, $153 and $214; and Check, $97 and $14, respectively. Based on the net return in dollars per acre, the best strategy during 1975 was Management and during 1976, Commercial, but, when both

PAGE 103

95 strategies are considered for the two years, Management appears to handle tomato pests as sound as current conventional.

PAGE 104

REFERENCES CITED Anonymous. 1965. Losses in Agriculture. U.S.D.A. Agr. Res. Serv. Agr. Handbook 291. Anonymous. 1974. Vegetable summary 1974. Florida Agricultural Statistics. Fla. Crop and Livestock Reporting Service. Anonymous. 1975. Agricultural statistics. U.S.D.A. Statistical Reporting Service. Apple, J.L. 1972. Intensified pest management needs of developing nations. Bioscience. 22:461-463. Bar, R.O. 1972. Ecologically and economically compatible pest control in Insects: Studies in population management. Geier, P.W., L.R. Clark, D.J. Anderson, and H.A. Nix (Ed.). Ecol. Soc. Austr. Camberra. (Memoirs 1). pp 241-264. Baranowski, R.M. 1959a. Effects of combining hydrocarbon insecticides with parathion or diazinon for leafminor control on tomatoes. Proc. Fla. State Hort. Soc. 72:155-158. Baranowski, R.M. 1959b. Preliminary work with systemic insecticides on tomatoes. Proc. Fla. State Hort. Soc. 72:158-160. Barrett, J.R. Jr., H.D. Dey, and J.G. Hartsock. 1971. Reduction in insect damage to cucumbers, tomatoes and sweet corn through use of electric light traps. J. Econ. Entomol. 64:1241-1249. Batiste, W.C., J. Joos, and R.C. King. 1970. Studies on sources of the tomato pinworm attacking tomatoes in northern California. J. Econ. Entomol. 63:1484-1486. Benham, C.B. Jr. 1974. Pest management: A student commentary on contemporary problems. Bull. Entomol. Soc. Amer. 20:319-326. Brooke, D.L. 1976. Costs and returns from vegetable crop in Florida. Season 1974-1975, with comparisons. Agr. Exp. Sta. IFAS Univ. of Fla. Economic information. Report 49. Bryan, H.H., and J.W. Strobel. 1967. Effects of plant populations and fertilizer rates on tomato yields on rockdale soil. Proc. Fla. State Hort. Soc. 80:149-156. Burgis, D.S. 1973a. Herbicides for the full bed mulch tomato culture system. I: Row middles. Proc. South. Weed Sci. Soc. 26:196-200. 9 6

PAGE 105

97 Burgis, D.S. 1973b. Herbicides for the full bed mulch tomato culture system. II: In the row. Proc. South. Weed Sci. Soc. 26:201-204. Burgis, D.S., and R.A. Levins. 1974. Pruning determinate tomato plants will increase dollar return. Proc. Fla. State Hort. Soc. 87:122-124. Campell, R.W. 1971. Developing a pest population management system. Proc. Tall Timbers conference on ecological animal control by habitat management. 3:9-20. Canerday, T.D., J.W. Todd, and J.D. Dilbeck. 1969. Evaluation of tomatoes for fruitworm resistance. J. Ga. Entomol. Soc. 4:51-54. Carlson, G.A. 1970. A decision theoretic approach to crop disease prediction and control. Amer. J. Agr. Econ. 52:216-223. Chalfant, R.B. 1973. Chemical control of the southern green stinkbug, tomato fruitworm and potato aphids on vining tomatoes in southern Georgia. J. Ga. Entomol. Soc. 8:279-283. Chant, D.A. 1964. Strategy and tactics of insect control. Canad. Entomol. 96:182-201. Chiarappa, L. H.C. Chiag, and R.F. Smith. 1972. Plant pests and diseases: assessment of crop losses. Science. 176:769-773. Clark, L.R., P.W. Geier, R.D. Hughes, and R.F. Morris. 1967. The ecology of insect populations in theor and practice. Methuen and Co. London. p 232. Corbet, P.S. 1970. Pest management: objectives and prospects on a global scale. In: Concepts of pest management. Rabb, R.L., F.F. Guthrie (Ed.). H.C. State Univ. Press, Raleigh. PP 191-205. Creiehton, C.S., T.L. McFadden and R.B. Cuthbert. 1971. Control of caterpillars on tomatoes with chemical and pathogens. J. Econ. Entomol. 64:737-739. Creighton, C.S., T.L. McFadden, and R.B. Cuthbert. 1973. Tomato fruitworm: control in South Carolina with chemical and microbial insecticides. 1970-1972. J. Econ. Entomol. 66:473-475. Creighton, C.S., and T.L. McFadden. 1976. Field tests of insecticidal sprays and baits for control of tomato fruitworm on tomatoes. J. Ga. Entomol. Soc. 11:101-105. Crill, J. P., J.W. Strobel, and B. Villalon. 1970. Effect of tobacco mosaic virus on fruit yield of tomato. Phytopathology. 60:1288. (Abstract)

PAGE 106

98 Crill, J. P., D.S. Eurgis, J. P. Jones, and J.W. Strobel. 1973. Effect of tobacco mosaic virus on yield of fresh-market, machine-harvest type tomatoes, riant Dis. Reptr. 57:78-81. Davis, D.R., R.R. Kincaid, and F.M. Rhodes. 1970. Mulches reduce soil temperature under tomato and totacco plants in Florida. Proc. Fla. State Hort. Soc. 83:117-119. Deevey, E.S. 1947. Life tables for natural populations of animals. Quart. Rev. Biol. 22:283-314. Elmore, J.C., and A.F. Howland. 1943. Life history and control of the tomato pinworm. U.S.D.A. Tech. Bull, p 841. Fery, R.L., and F.P. Cuthbert, Jr. 1974a. Effect of plant density on fruitworm damage in the tomato. Hort. Sci. 9:140-1'41. Fery, R.L., and F.P. Cuthbert, Jr. 1974b. Resistance of tomato cultivars to the fruitworm, Heliothis zea (Boddie) Hort. Sci. 9:469-470. Fery, R.L., and F.P. Cuthbert, Jr. 1975. Antibiosis in Lycopersicon to the tomato fruitworm ( Heliothis zea ). J. Amer. Soc. Hort. Sci. 100:276-278. Geier, P.W., and L.R. Clark. 1960. An ecological approach to pest control. IUCN Symposium. pp 225-233. Geraldson, CM. 1962. Growing tomatoes and cucumbers with high analysis fertilizer and plastic mulch. Proc. Fla. State Hort. Soc. 75:253-260. Geraldson, CM. 1963. Quantity and balance of nutrients required for best yields and quality of tomatoes. Proc. Fla. State Hort. Soc. 76:153-158. Geraldson, CM., A.J. Overman and J. P. Jones. 1965. Combination of high analysis fertilizers, plastic mulch and fumigation for tomato production on old agricultural land. Proc. Soil and Crop Sci. of Fla. 25:18-24. Giese, R.L., R.M. Peart, and R.T. Huber. 1975. Pest management: A pilot project exemplifies new ways of dealing with important agricultural pests. Science. 187:1045-1052. Gonzalez, D. 1970. Sampling as a basis for pest management strategies. Proc. Tall Timbers conference on ecological animal control by habitat management. 2:83-101.

PAGE 107

99 Hall, F.R. 1974. Bioeconomics of apple pests: cost appraisal of crop injury data. J. Econ. Entomol. 67:517-521. Harcourt, D.G. 1970. Crop life tables as a pest management tool. Canad. Entomol. 102:950-955. Harding, J. A. 1971. Field comparisons of insecticidal sprays for control of four tomato insects in south Texas. J. Econ. Entomol. 64:1302-1304. Hayslip, N.C. 1943. Notes on biological studies of mole crickets at Plant City, Florida. Fla. Entomol. 26:33-46. Hayslip, N.C, R.J. Allen and J.F. Darby. 1952. A vegetable-pasture rotation study at the Indian River Field Laboratory. Proc. Fla. State Hort. Soc. 65:148-153. Hayslip, N.C, E.M, Hodges, D.W. Jones, and A.E. Kretschmer, Jr. 1964. Tomato and pangolagrass rotation for sandy soils of south Florida. Agr. Exp. Sta. Univ. of Fla. Circular S-153. 24 p. Headley, J.C 1975. The economics of pest management. In: Introduction to insect pest management. Metcalf, R.L. and W.H. Luckman (Ed.). John Wiley and Sons, Inc., New York, pp 75-99. Hett, J.M., and O.L. Loucks. 1968. Application of life table analysis to tree seedlings in Quetico provincial park. Ontario. For. Chron. 44:29-32. Hills, O.A. and E.A. Taylor. 1951. Parasitization of dipterous leafminers in cantaloupes and lettuce in the Salt River Valley, Arizona. J. Econ. Entomol. 44:759-782. Huffaker, C.B. 1974. Some ecological roots of pest control. Entomophaga. 19:371-389. Hurting, H. 1964. The decision-making process and insect control. Canad. Entomol. 96:221-230. Jaworski, C.A. 1965. Effect of dolomitic limestone on tomato transplant growth, quality and mineral composition. Proc. Fla. State Hort. Soc. 78:155-162. Johnson, F.A., J.E. Brogdon, R.S. Mullin, T.A. Kucharek and D.W. Dickson. 1974. Commercial vegetable insect-disease and nematode control guide. Fla. Coop. Ext. Serv. IFAS. Univ. of Fla. Circular 193H. 75 pp. Johnson, A.W. N.C. Glaze, and C.A. Jaworski. 1975. Combinations of specific pesticides for multiple pest control on tomato. J. Amer. Soc. Hort. Sci. 100:203-206. Jones, H.A. and J.T. Rosa. 1928. Truck crop plants. McGraw-Hill Book Company, New York. 538 pp.

PAGE 108

100 Jones, J. P., and J. P. Crill. 1973. The effect of verticlllium wilt on resistant, tolerant, and susceptible tomato varieties. Plant Dis. Reptr. 57:122-124. Jones, J. P., and E.G. Kelsheimer. 1963. The compatibility of several fungicides and insecticides used for the control of diseases, lepidopterous larvae and leaf miners of tomato. Proc. Fla. State Hort. Soc. 76:126-130. Jones, J. P., and S.S. Woltz. 1972. Effect of soil ph and micronutrient amendments on verticillium and fusarium wilt on tomato. Plant Dis. Reptr. 56:151-153. Jones, J. P., A.J. Overman, and CM. Geraldson. 1972. The effect of mulching on the efficacy of DD Mencs for control of fusarium wilt on tomato. Plant Dis. Reptr. 56:953-956. Kelbert, D.G.A., P.H. Everett, A.J. Overman, CM. Geraldson, E.G. Kelsheimer, J.O. Jones, D.S. Burgis and E.L. Spencer. 1966. Tomato production on the sandy soils of south Florida. Agr. Exp. Sta. IFAS Univ. of Fla. Gainesville. Bull. 710. p 41. Levins, R.A. and CM. Geraldson. 1974. Production cost for ManateeRuskin staked tomatoes, 1974. Bradenton AREC Res. Reptr. G C 1974-10. Levins, R.A. S.L. Poe, R.C Littell and J. P. Jones. 1975. Effectiveness of a leaf miner control program for Florida tomato production. J. Econ. Entomol. 68:772-774. Locascio, S.J., and J.M. Myers. 1974. Tomato response to plug-mix mulch and irrigation method. Proc. Fla. State Hort. Soc. 87:126-130. Luckman, W.H., and R.L. Metcalf. 1975. The pest management concept. In: Introduction to insect pest management. Metcalf, R.L., and W.H. Luckman (Ed.). John Wiley and Sons, Inc. New York, pp 3-35. Madden, A.H. 1945. Biology of the tobacco hornworm in the southern cigar-tobacco district. U.S.D.A. Tech. Bull. 896. Marvel, M.E., and J. Montelaro. 1966. Tomato production guide. Univ. of Fla. IFAS Fla. Agr. Ext. Serv. Circular 98c. Middlekauff, W.W. CQ. Gonzales, and R.C King. 1963. Effect of various insecticides in the control of caterpillars attacking tomato in California. J. Econ. Entomol. 56:155-158. Murphy, W.S. 1965. Influence of various nitrogen fertilizers on growth and nutrition of southern grown tomato transplants. Proc. Fla. State Hort. Soc. 78:191-197. Murray, W.S. 1969. Economic and pesticides. Proc. Entomol. Soc. Ontario. 100:29-39.

PAGE 109

101 Musgrave, C.A., S.L. Poe, and D.R. Bennett. 1975. Leaf miner population estimation in polycultured vegetables. Proc. Fla. State. Hort. Soc. 88:156-160. Napompeth, B. and T. Nishida. 1974. Life table and pest management of corn. Proc. Hawaiian Entomol. Soc. 21:419-424. Nickel, J.L. 1973. Pest situations in changing agricultural systems A review. Bull. Entomol. Soc. Amer. 19:136-142. Norgaard, R. 1976. The economics of improving pesticide use. Ann. Rev. Entomol. 21:45-60. Oatman, E.R. 1970. Ecological studies of the tomato pinworm on tomato in southern California. J. Econ. Entomol. 63:1531-1534. • Oatman, E.R., and G.R. Planter. 1971. Biological control of the tomato fruitworm, cabbage looper, and hornworms on processing tomatoes in southern California, using mass releases of Trichogramma pretiosum J. Econ. Entomol. 64:501-506. Oatman, E.R., and G.C. Kennedy. 1976. Methomyl induced outbreak of Liriomyza sativae on tomato. J. Econ. Entomol. 69:667-668. ^ Odum, E.P. 1971. Fundamentals of ecology. W.B. Saunders. Philadelphia, p 574. Ordish, G. 1962. Economics and pest control. World Rev. Pest Control. 1:37-38. Overman, A.J., and J. P. Jones. 1968. Effect of polyethylene mulch on yields of tomatoes infested with root-knot nematodes. Proc. Soil and Crop Sci. Soc. of Fla. 28:258-262. Overman, A.J. 1975. Nematicides in linear drip irrigation for full-bed mulch of tomato. Proc. Soil and Crop Sci. Soc. of Fla. 34:197-200. Poe, S.L. 1974a. Emergence of Keiferia lycopersicella (Lepidoptera Gelechiidae) and Apanteles spp. (Hymenoptera : Braconidae) from pupae and soil treated with insect growth regulators. Entomophaga. 19:205-211. Poe, S.L. 1974b. Selective application of insecticides for sustained fruit yield of tomato. Proc. Fla. State Hort. Soc. 87:165-169. Poe, S.L. 1976. Reinf estation of treated tomato fields by mole crickets. Fla. Entomol. 59:80. Poe, S.L., and P.H. Everett. 1974. Comparison of single and combined insecticides for control of tomato pinworm in Florida. J. Econ. Entomol. 67:671-674.

PAGE 110

102 Poe, S.L., J. P. Crill, and P.H. Everett. 1975. Tomato pinworm population management in semitropical agriculture. Proc. Fla. State Hort. Soc. 88:160-164. Porte, W.S., and J. Wilcox. 1963. Commercial production of tomatoes. U.S.D.A. Farmers Bull. p 2045. Rabb, R.L. 1970. Introduction to the conference. In: Concepts of pest management. Rabb, R.L., and F.F. Guthrie (Ed.). N.C. State Univ. Press, Raleigh, pp 1-5. Rabb, R.L., R.E. Stinner, and G.A. Carlson. 1974. Ecological principles as basis for pest management in the agroecosystem. In: Proc. Summer Inst. Bio. Control of plant, insect and diseases. Maxwell, F.G., and F.A. Harris (Ed.), pp 19-45. Ruesink, W.G. 1976. Status of the system approach to pest management. Ann. Rev. Entomol. 21:27-43. Shorey, J.H. and I.M. Hall. 1963. Toxicity of chemical and microbial insecticides to pest and beneficial insects on poled tomatoes. J. Econ. Entomol. 56:813-817. Short, D.E., and D.P. Driggers. 1973. Field evaluation of insecticides for controlling mole crickets in turf. Fla. Entomol. 56:19-23. Simons, J.N. 1962. The pseudo-curly top disease in south Florida. J. Econ. Entomol. 55:358-363. Smith, R.F. 1969. The importance of economic injury levels in the development of integrated pest control programs. Qual. Plant Mater. Veg. 17:81-92. Smith, R.F. 1970. Pesticides: their use and limitations. In: Concepts of pest management. Rabb, R.L. and F.F. Guthrie (Ed.). N.C. State Univ. Press, Raleigh, pp 103-118. Smith, R.F. 1971. Economic aspects of pest control. Proc. Tall Timbers conference on ecological animal control by habitat management. 3:53-83. Solomon, M.E. 1972. Ecology in relation to the management of insects. In Insects: studies in population management. Geier, P.W. L.R. Clark, D.J. Anderson, and H.A. Nix (Ed.). Ecol. Soc. Austr. Camberra. (Memoirs 1): 154-164 Southwood, T.R.F., and G.A. Norton. 1972. Economic aspects of pest management strategies and decisions. In Insects: studies in population management. Geier, P.W. L.R. Clark, D.J. Anderson, and H.A. Nix (Ed.). Ecol. Soc. Austr. Camberra. (Memoirs 1): 168-181.

PAGE 111

103 Springett, B.P. 1972. On ecosystem strategy. In Insects: studies in population management. Geier, P.W. L.R. Clark, D.J. Anderson, and H. A. Nix (Ed.). Ecol. Soc. Austr. Camberra. (Memoirs 1): pp 80-83. Swank, G.R. 1937. Tomato pinworm ( Gnorimoschema lycop ersicella (Busck)) in Florida. Fla. Entomol. 20:33-42. Stephens, J.M. 1973. Growing tomatoes in the Florida vegetable garden. Coop. Ext. Serv. IFAS Univ. of Fla., Gainesville. Circular 279-C. p 16. Stern, V.M. R.F. Smith, R. .van den Bosch, and K.S. Hagen. 1959. The integrated control concept. Hilgardia. 29:81 Thompson, H.C. 1949. Vegetable crops. McGraw-Hill Book Company. New York. p 611. Varley, G.C. G.R. Gradwell, and M.O. Hassell. 1974. Insect population ecology: an analytical approach. Univ. of California Press, Berkeley and Los Angeles, California. p 212. Walter, J.M., and E.C. Kelsheimer. 1949. In the row application of soil fumigants for vegetables on sandy soils. Proc Fla. State Hort. Soc. 62:122-126. Waters, W.E. 1969. The life table approach to analysis of insect impact. J. For. 67:300-304. Way, M.J. 1972. Objectives, methods and scope of integrated control. In Insects: studies in population management. Geier, P.W., L.R. Clark, D.J. Anderson, and H.A. Nix (Ed.). Ecol. Soc. Austr. Camberra. (Memoirs 1):137-152. Webb, R.E., A.K. Stoner, and A.G. Gentile. 1971. Resistance to leaf miners in Lycopersicon accessions. J. Amer. Soc. Hort. Sci. 96:65-67. Weber, P.V.V. 1960. The effect of tobacco mosaic virus on tomato yield. Phytopathology. 50:235-237. Wene, G.P. 1953. Control of the serpentine leaf miner on peppers. J. Econ. Entomol. 46:789-793. Wene, G.P. 1955. Effects of some organic insecticides on the population level of the serpentine leaf miner and its parasites. J. Econ. Entomol. 48:596-597. Wilcox, J., A.F. Howland, and R.E. Campell. 1956. Investigations of the tomato fruitworm, its seasonal history and methods of control. U.S.D.A. Tech. Bull. 1147.

PAGE 112

104 Wilcox, G.E., and R. Langston. 1960. Effect of starter fertilization of early growth and nutrition of direct-seeded and transplanted tomatoes. Proc. Amer. Soc Hort. Sci. 75:584-594. Wilcox, G.E., G.C. Martin and R. Langston. 1962. Root zone temperature and P treatment effects on tomato seedling growth in soil and nutrients solutions. Proc. Amer. Soc. Hort. Sci. 80:522-529. Wolfenbarger, D.O. 1947. The serpentine leaf miner and its control. Fla. Agr. Exp. Sta. Press Bull. 639. Wolfenbarger, D.O. 1954. A comparison of dilute and concentrate sprays for control of insects of potato and tomato. J. Econ. Entomol. 47:537-539. Wolfenbarger, D.O. 1958. Serpentine leaf miner: brief history and summary of a decade of control measures in south Florida. J. Econ. Entomol. 51:357-359. Wolfenbarger, D.O., J. A. Cornell, S.D. Walker, and D.A. Wolfenbarger. 1975. Control and sequential sampling for damage by the tomato pinworm. J. Econ. Entomol. 68:458-460. Wolfenbarger, D.O. and W.D. Moore. 1967. Mulch treatments of squash and tomatoes with respect to virus infestations and yields. Proc. Fla. State Hort. Soc. 80:217-221. Wolfenbarger, D.O. and S.L. Poe. 1973. Tomato pinworm control. Proc. Fla. State Hort. Soc. 86:139-143. Wolfenbarger, D.A. and D.O. Wolfenbarger. 1966. Tomato yields and leaf miner infestations and a sequential sampling plant for determining need for control treatment. J. Econ. Entomol. 59:279-283. Woltz, S.S., and J. P. Jones. 1973. Interactions in source of nitrogen fertilizer and liming procedure in the control of fusarium wilt of tomato. Hort. Sci. 8:137-138.

PAGE 113

BIOGRAPHICAL SKETCH Jose Alonso Alvarez Rodriguez was born July 30, 1937, in Medellin, Antioquia, Republic of Colombia. He was graduated from "Liceo Nacional Marco Fidel Surez" in December, 1957, He received his "Ingeniero Agronomo" degree from "Universidad Nacional de Colombia," Medellin, in 1962. After graduation he accepted the position of "Entomologo Auxiliar" with "Instituto de Fomento Algodonero." He held this position for two years. In March, 1965, he accepted the position of "Entomologo Auxiliar" with "Instituto Colombiano Agropecuario In September, 1969, he was awarded a two-year scholarship from the Rockefel ler Foundation and enrolled at "Colegio de Postgraduados Chapingo, Mexico. He majored in Entomology and was graduated in September, 1971 with the degree of Master of Science. He then returned to Colombia to conduct research as an assistant in the Program of Entomology of the "Instituto Colombiano Agropecuario." In September, 1974, he started graduate studies at the University of Florida toward his doctoral degree He has been financially assisted by the "Instituto Colombiano Agropecuario" through the "Instituto Colombiano de Credito Educativo y Estudios Tecnicos en el Exterior." He is married to Lilia Dolores Aguilar Leal. They have three children, Carlos Alberto, Julio Cesar, and Luis Eduardo. 105

PAGE 114

I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Sidney L.^/Poe, Chairman Associate Professor of Entomology and Nematology I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Stephe^ R. Kostewicz Assistant Professor of Vegetable Crops I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Vernon G. Perry Professor, Entomology and Nematology I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Reece I. Sailer Professor, Entomology and Nematology

PAGE 115

This dissertation was submitted to the Graduate Faculty of the College of Agriculture and to the Graduate Council, and was accepted as partial fulfillment of the requirements for the degree of Doctor of Philosophy. March 1977 Dean, Graduate School