71c O' to
VEGETABLE FIELD DAY
AGRICULTURAL RESEARCH AND EDUCATION CENTER
BELLE GLADE, FLORIDA
flAY 10, 1979
UNIVERSITY OF FLORIDA
INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES
VEGETABLE FIELD DAY
Agricultural Research and Education Center
Belle Glade, Florida
flay 10, 1979
Kenneth D. Shuler, Presiding
Palm Beach County Extension Agent
8:30 A.il. Registration
9:00 Introduction and Remarks
Kenneth Shuler and Thomas Zitter
WATER, SOIL AND RICE RESEARCH
9:10 Crop Production at a High Water Table 1
9:20 Land Forming in the Everglades Agricultural Area 9
S. F. Shih
9:30 The Economic Potential for Incorporating Rice Into Vegetable 12
G. H. Snyder* and J. Alvarez
SWEET CORN RESEARCH
9:40 Comparison of Florida Staysweet With Standard Sweet Corn 19
Hybrids Grown on the Organic Soils of the Florida Ever-
glades in the Fall, 1978
9:50 Price-Acreage Relationships for Florida Sweet Corn 22
10:00 Break Drinks courtesy of Asgrow of Florida
10:15 Lettuce Breeding 24
V. L. Guzman* and T. A. Zitter
10:25 Preliminary Investigations on the Nutrient Requirements of 26
Crisp-head Lettuce Cultivars
V. L. Guzman and R. E. Lucas*
10:35 Liquid Fertilizers 41
R. E. Lucas
10:45 Seed Priming to Overcome Thermodormancy in Lettuce During 43
A. C. Guedes, D. J. Cantliffe, Ernest Hunter, and
K. D. Shuler
10:55 Celery breeding (no written summary)
11:05 Preliminary Report on flesurolR to Repel Birds From Pulling 48
Seedling Rice Plants
W. G. Genung* and G. H. Snyder
11:15 Summary of Research on Rhizoctonia Root Rot and Stalk Rot 55
D. J. Pieczarka
SAND LAFID RESEARCH
11:25 Methods for Controlling the Most Common Vegetable Viruses 59
in South Florida
Thomas A. Zitter
11:35 Effect of Bacterial Spot (Xanthomonas vesicatoria) on 65
11:45 Vegetable Research on Sandy Soils of the Lower East Coast, 69
H. Y. Ozaki
1:15 Tour of experimental plots to include:
Celery Integrated Pest Management U. G. Genung
Celery Stalk Rot Control Trials D. J. Pieczarka
Sweet Corn Breeding E. A. Wolf
Rice Research Plots G. H. Snyder
Sugarcane -- Hater Table Research G. Kidder
CROP PRODUCTION AT A HIGH IATER TABLE
The only practical means available for slowing the rate of organic soil sub-
sidence while continuing to use the soil for agricultural purposes is the mainte-
nance of ground water tables which are as high as possible for the particular crop
being grown. A change in water table height may cause management problems not
experienced with lower water tables. These problems might take the form of reduced
production or quality of the crop, or increased difficulties with water control or
In order to evaluate the problems associated with higher water tables in
sugarcane production, an experiment was installed in the fall of 1976 at the AREC
delle Glade. In this experiment the water table has been held as near to 40 cm
(16 in) as possible since the experiment began. Two plantings were made, one in
January 1977 and the other in January 1978. The varieties being tested in Stage IV
of the variety development program were used in these experiments. Results of the
two plantings were compared with like plantings at the two Stage IV sites most
closely located to AREC Belle Glade, i.e., those on the Duda and Iledgworth farms.
We now have data from two harvests, 1977 and 1978. Tonnage of cane and sugar, and
percent sucrose are shown in the attached figures.
In the 1977 plant cane crop the most striking result was the high percent of
sugar in the cane grown under high water table conditions. At the AREC Belle Glade
location the sugar per ton of cane averaged 20 to 45 pounds higher than the average
of all Stage IV locations and all varieties produced sweeter cane there than any-
where else. Sugar per acre, the net result of sugarcane production, was lower in
the AREC high water table plots than at the Duda location but was higher than at
the I'edgworth location for all varieties. Furthermore, sugar per acre at the high
water table was greater than the average of the five Stage IV locations on sawgrass
mucks (Terra Ceia and Pahokee series). Thus it seemed from the first year's data
that high water table in sugarcane reduced the tonnage but significantly increased
the sugar per ton of cane and resulted in no overall loss of sugar production per
acre. The advantages of hauling less tonnage of cane to the mill for the same
amount of sugar is obvious.
G. KIDDER is Extension Sugarcane Specialist, University of Florida, Department
of Agronomy, located at AREC Belle Glade.
The higher percentage of sugar in cane observed in the plant cane crop grown
under high water table was not observed in the first ratoon crop. This effect,
coupled with the lower tonnage of cane, resulted in greatly lowered production of
sugar per acre under high water tables in the first ratoon crop. The data are
still being analyzed and at present it is not understood why the percent sugar
should have changed so drastically from one year to the next. It had been reasoned
from the plant cane data that the stress put on the cane by the higher water table
had resulted in the sweeter cane and lower tonnage. 1Ihy part of this effect was
lost in the first ratoon is not presently understood.
The 1978 plant cane data has not yet been analyzed. These data should help
clarify the results seen in the first planting. The experiment is scheduled to
continue until both the 1977 and 1978 plantings have produced their second ratoon
crops. By the time these plantings have run their course it is hoped that the
effects of growing sugarcane with water tables higher than customary will be better
The help of the following in carrying out this experiment is gratefully acknow-
ledged: Sugarcane Growers Cooperative of Florida for harvesting the plots; USDA
Canal Point for seed cane, assistance with data collection, and sugar analysis of
the cane; USDA Harvester Lab for assistance with harvest; and A. Duda & Sons for
loan of equipment. I would also like to acknowledge the help of colleagues at
AREC Belle Glade and to Mr. Ed Rice, USDA, for use of some of his yet unpublished
data. Some data in this report is from Mr. Rice's report, "Sugarcane Variety Test
in Florida, 1977-78 Harvest Season."
CAHE TOililAGE 1977 PLWIT CA:!E
CAlIE TOkiJAGE 1973 FIRST RATO01
PIERCE T SUGAR II] CA'E 1977 PLCi:T CAnE
.L. ,-- _ _ __ _^- - *
PERCENT SUGAR I1! CAiE 1973 FIRST RAT001O
- - -AREC
SUGAR TO;iAGE 1977 PLAi'!T CANE
SUGAR TOTIAGE 1978 FIRST RAT00R
1 \ .
LAND FORMING IN THE EVERGLADES AGRICULTURAL AREA
S. F. Shih
Land forming, which includes either land sloping, land leveling or land smooth-
ing is the modification of the topography of the land to provide a field surface
that would move water off the field rapidly enough to prevent flooding but slow
enough to permit adequate infiltration with reduced runoff and erosion. It im-
proves surface drainage by eliminating low area and areas of no slope. There are
a large number of advantages accruing from land forming. The practice of land
1) Provides a land surface that will drain water from a field rapidly enough
to prevent damage from flooding, but slowly enough to permit adequate in-
2) Improves surface drainage by eliminating low areas and areas of no slope.
3) Reduces the number of surface ditches required for good drainage because
each furrow carries its own water.
4) Reduces erosion because water cannot concentrate in natural drainage ways.
5) Reduces ditch maintenance by eliminating some deep ditches.
6) Makes possible large fields.
7) Increases machinery efficiency because point ro'!s are eliminated and ma-
chinery can be operated at higher speeds.
8) Provides better crop and soil management because the uniform ground sur-
face allows precision planting and fertilizer placement, which results in
more uniform germination and maturations.
9) Increases crop yields because of better soil and crop management.
10) Reduces the subsidence rate because the uniform high water table depth can
11) Improves the water quality due to the decreasing of subsidence rate and
better water management system.
Studies done in North Carolina have indicated that as much as 15% increase
in cropping area can be obtained under ideal conditions. All these advantages are
of course related to smooth surface topography without any depressions and bumps,
etc., in the field. Intensive research investigations done in various parts of
the United States, such as California, Arkansas, Texas and others even including
humid areas like north Carolina and Louisiana, have indicated significant increases
in yields of different crops due to land forming if executed properly. Statistics
given out in 1968 by Reynold Research and Manufacturing Corporation in McAllen,
Texas showed that savings from various planting operations on land formed area
could amount to as much as $26.50 per acre due to increase in operational effi-
ciency. Proper land forming, even without considering the additional available
cropping area, could increase field by about 8-11%.
Land forming is of special interest in Everglades because of the type of soil
we have, because of the problems associated with the subsidence, because of the
rice field for even flooding, and particularly because of the climatic patterns of
uneven wet and dry periods specific to this area. Need of maintaining high water
table to reduce subsidence of our natural resource the organic soil and to ef-
fectively control insects can be better met if the land is well formed. Shallow
muck soil with underlying uneven rock bed can be managed efficiently by improving
surface water management systems for which land with smooth topography is a must.
About eight years ago while working at North Carolina State University Dr.
George Kriz (now Assistant Director of Research there) and myself introduced five
different types of land forming designs. Ue also developed a new method of earth-
work calculations for these designs. The different types of land forming designs
afford more flexibility on basis of original conditions of the land topography and
they encompass crop requirements as well. These designs include:
Type I. According to this design, there should be uniform slope (plane sur-
face in both row and cross row directions with row and cross row drainage.
Type II. This design has variable slope in both row and cross directions
with row and cross row drainage.
Type III. This design calls for uniform slope in individual rows in row
direction and variable slope in cross row direction with row and cross
Type IV. In this design, there is uniform slope in individual rows with row
drainage and a minimum and maximum allowable cross row slope. There is
no cross row drainage provision in this design.
Type V. This design, which is the least expansive of all in terms of earth-
work volume, specifies variable slope in individual rows with row drainage
and a minimum and maximum allowable cross row slope without any cross row
Hle also developed computer programs for these designs to calculate earthwork
quantities for both regular and irregular (nonrectangular) fields. All the five
designs can be compared for a given set of field conditions and the best topography
that exists in this area, designs I and III are the most expansive as they need
more earthwork to be done. However, they represent the ideal conditions, Designs
II, IV and V, in that order, come next in the amount of earthwork to be done, but
these designs represent a certain degree of closeness to the original conditions
in the field. Depending on the requirements of the crop, the cheapest design could
be selected out of these five. However, if a flat slope (i.e., near zero slope) is
desired as required for crops.like rice, then all the designs would give similar
Field elevations taken at 100-feet grid interval provide input for the program.
The new He-Ne .laser technique can speed up process of data collection significantly
and before land forming operations is commenced, analysis of data can provide the
best type that could be used. The computed elevations could be used to guide the
laser plane to get the surface smoothed with or without grade. Land forming de-
signs comparison can be best explained by an example. le took elevation data from
a rectangular sugarcane field about 40 acres in area (belonging to Seminole Sugar
Corp). The maximum and minimum slopes used were 6 inches per mile and zero inch
(flat) in both row and cross row directions, respectively. The results of earth-
work to be done were 180, 170, 178, 111 and 110 cubic yards per acre for Design
Types I, II, III, IV and V, respectively.
The Economic Potential for Incorporating Rice into Everglades Vegetable
G.H. Snyder and J. Alvarez2
Abstract. Vegetables are grown on about 50 thousand acres of organic
soils in the Florida Everglades Agricultural Area each winter season. This
land is generally idle during the summer. Growers often flood idle land to
help control pests, to improve soil tilth and to reduce biological oxida-
tion of the organic soil. Rice (Oryza sativa) is sometimes planted as a
cover crop, but is not harvested for grain. An economic analysis reveals
that rice could be grown for grain at a profit in rotation with vegetable
crops, in spite of additional costs incurred with grain production.
Over 90 million dollars worth of vegetables are produced annually on
about 50 thousand acres in the Everglades Agricultural Area. Crops are
produced primarily during the winter season when other vegetable growing
regions of the eastern United States are not in production. During the
summer months the vegetable land in the Everglades is idle.
The Agricultural Area, which extends south from Lake Okeechobee, is
composed of organic soils that generally contain less than 15% mineral
matter, by weight. Like all drained organic soils, the Everglades soils
are being lost (subsiding) by microbial oxidation. Flooding essentially
stops oxidation and, along with the use of high water tables during crop
production, can conserve organic soils. Many growers flood their land
during the summer to aid in nematode, insect, disease and weed control.
Flooding is also used to improve soil tilth. Some growers plant rice
(Oryza sativa) in the summer to further suppress weeds and improve soil
tilth. The rice is disked into the soil before any grain is produced.
In this paper we will explore the possibilities of increasing farm
income by including rice in the normal vegetable production cycle.
Adapted from the Proceedings of the Florida State Horticultural Society,
Volume 90, 1977. pp. 380-382.
Associate Professor of Soil Science and Assistant Professor of Food and
Resource Economics, respectively, Agricultural Research and Education
Center, Belle Glade.
Fitting Rice into the Vegetable Production Cycle
The average time from seeding to maturity of rice vareities which
may produce well in Florida ranges from 115 to 140 days. Rice can be
planted from March through July and harvests can be continued through
December. Vegetable growers generally stagger plantings to provide a more
continuous harvest period. Vegetable planting in the Everglades begins in
mid to late August and harvest ends in mid-fay to June (Table 1). Thus
growers could not wait until all vegetable harvesting ceases before plant-
ing rice nor could all rice be harvested before any vegetable planting is
started. Growers would have to integrate rice and vegetable operations
during certain periods of the year. Using beans or sweet corn as an ex-
ample, fields that are harvested after the end of larch would not normally
be replanted until fall, probably no sooner than mid-August, approximately
135 days later. Vegetable planting in the fall could be delayed in those
fields that had been harvested later in the previous spring to give the
same time interval. Thus it should be possible to fit a crop of one of
the earlier maturing rice varieties into this time span. It would be more
difficult to fit a crop of rice into a radish operation, but it would be
easier to grow rice in rotation with certain leafy crops or potatoes. For
example, some lettuce fields could be available from mid-February to the
end of August, a period of nearly 200 days. Since vegetable growers do
not always plant the sane vegetable crop in a particular field that was
grown there the previous season, many combinations of successive vegetable
crops are possible. A rice crop should fit into many of these combina-
An Economic Analysis
Estimated costs associated with planting and harvesting rice have
been developed for the Everglades, using information obtained from local
growers and from other sources (Table 2). Yields of 35-55 hundred weight
(cwt) have been obtained in the Everglades. The cash return to the
grower will vary with the yield and market price, as is shown in Table 3.
In recent weeks, good quality long grain rough rice has been selling for
$8.50 to $10.50/cwt and prices are expected to continue the upward trend.
Thus profits could range from $24 to $333 per acre (Table 3): Many vegetable
growers flood their land during the summer and some grow rice as a cover
crop solely for the benefits these practices provide to the following
vegetable crops. By harvesting the rice, growers should at least be able
to recover the costs incurred in summer flooding and cover crop manage-
ment, and are likely to increase their overall income as well.
Rice has been grown for grain in the Everglades both commercially
and experimentally. Considerable information is available on rice pro-
duction in this area, though much of it was obtained in the 1950's and
is not fully applicable today. No major problems appear to preclude
rice production in this region but measures must be taken to overcome
certain disease and nutritional problems. Some production problems need
further research. These include the effect of varieties, growth stage,
fertility and planting date on diseases, insects and birds, and the ef-
fect of rice upon other crops in a rotation (soil and water management,
diseases, rice volunteering as a weed in rotational crops, particularly
in celery). Rice research presently being conducted at the AREC-Belle
Glade should help provide answers to these questions and should help up-
date and supplement the earlier reports. Of course, some problems
presently absent or unrecognized may arise when rice acreage expands.
It can only be hoped that such problems can be overcome through research
and skillful management. Considering the worldwide adaptation of rice,
the widespread intensive breeding programs that are being conducted and
the successes they have achieved, and the multitude of problems Ever-
glades growers have been able to deal with to produce the crops now grown
in this area, it seems likely that solutions will be found to any .rice
production problems that emerge.
Perhaps the biggest deterrent to rice production in the Everglades
has been the lack of local drying and milling facilities. However, last
year rice was dried here very successfully with recently constructed
equipment, and two1mills.are presently under construction which should
be available for this year's crop. These developments, plus the favor-
able outlook for rice prices, present Everglades growers a new opportunity
to augment their income without detracting significantly from their tradi-
tional main crop. Those interested in obtaining additional information on
rice are encouraged to review the following publications and the references
Alvarez, J. 1979. Field corn vs. rice in the Everglades: an application
of partial budgeting. University of Florida, IFAS, Food and Resource
Economics Department Economic Information Report 108.
Alvarez, J., G. Kidder and G.H. Snyder. 1979. The economic potential
for incorporating rice in Everglades sugarcane production systems. Soil
and Crop Sci. Soc. Proc. 38: (in press).
Alvarez, J. 1978. Potential for commercial rice production in the
Everglades. University of Florida, IFAS, Food and Resource Economics
Department Economic Information Report 98.
Snyder, G.H., J. Alvarez, J.H. ilishoe, D.L. fyhre, S.F. Shih and V.E.
Green, Jr. 1977. The economic potential for incorporating rice in
Everglades vegetable production systems. Proc. Fla. State Hort. Soc.
Table 1. Approximate planting and harvesting periods for vegetable
crops in the Everglades Agricultural Area.
Begins Ends Begins Ends
Beans (Phaseolus vulaaris)
Sweet Corn (Zea mays)
Lettuce (Lactuca sativa),
escarole and endive
Radish (Raphanus sativus)
Celery (Apium graveolens
var. dulce) -
Potato (Solanum tuberosum)
Cabbage (Brassica oleracea
Chinese Cabbage (Brassica
Aug. 15 Ilarch 31
Sept. 1 "larch 15
Sept. 1 March 31
Oct. 15 June 30
Oct. 1 June 15
Nov. 1 IMay 15
Oct. 1 lay 31
Nov. 1 June 30
Nov. 1 May 31
Dec. 15 Feb. 15
Nov. 15 April 30
Nov. 15 hay 31
Table 2.--Estimated costs and returns per acre
grown in the Everglades Agricultural
for 280 acres of rice
Item Unit Quant. Price Amount
Mach. & equip.
Interest (6 mo.)
Total variable costs
Mach. & equip.
Total Fixed costs
aIncludes harvesting, hauling, drying, and destroying the levees.
Table 3. Estimated annual returns per acre assuming different yields and
prices, for planting and harvesting rice in the Everglades.
Yield/acre Price Nlet Revenue1
$256, $260, $264, $268, and $272
1Assuming per acre production costs of
for each yield assumed, respectively.
Belle Glade AREC Research Report EV-1979-5 flay 1979
COMPARISON OF FLORIDA STAYSNEET IITH STANDARD SWEET CORN HYBRIDS
GROUH ON THE ORGANIC SOILS OF THE FLORIDA EVERGLADES IN THE FALL, 1978
Emil A. Wolfl/
Three tests were conducted. Tests 1 and 2 in comnsrcial fi'ld plantings of
Florida Staysweet and the third, number 3, at the Belle Glade AREC. The first
test was planted September 15. The second and third tests were planted on
September 21. Three hybrids, lobelle, Guardian (XP370), and Silverqueen, were
compared to Florida Staysweet in test 1. The same hybrids plus Wintergreen
were used in the.other two tests.
All seed was treated with 4 oz. a.i. Difolitan per 100 Ibs seed as a slurry
and air dried prior to planting. The Difolitan treatment was in addition to the
commercial treatment already on the seed. To insure perfect stands, seed was
hand planted 3 seed per hill with hills 9" apart in 18 ft. single rows. There
were four replications in a randomized complete blocks design. Young plants
were thinned to one per hill when approximately three weeks old. Fertilization,
disease and insect control on the commercial tests were made by the growers. At
the AREC, fertilization was based on soil tests and disease and insect control
were in accordance with station recommendations.
Results and Discussion
Plant growth of all hybrids was fair to poor in test number 1,
very good in test 2, and good in test 3. Plant height for Florida Staysweet
averaged 5.3 ft. in test 1, 7.3 in test 2, and 6.3 in test 3. A comparison of
days to harvest for the different hybrids in the three tests is given in Table 1.
The shorter maturity dates for the September 21 planting in test number 2 compared
with test number 3, AREC planting, was probably due to higher fertility level
and lower water table than at the AREC.
I/f Professor (Horticulturist), Agricultural Research and Education Center,
Belle Glade, Florida.
Table 1. Days to optimum maturity for sweet corn hybrids in 3 fall trials,
1978, Belle Glade,area.
Test No. 1 2 3
Hybrid Date Seeded Sept. 15 Sept. 21 Sept. 21
Iobelle 65 69 75
Guardian 63 68 69
Silverqucen 66 70 76
Florida Staysweet 68 71 75
Wintergreen -- 67 68
Incidence of Southern leaf blight caused by H. maydis, was quite heavy on
test 1, moderately heavy on test 2, and not quite so heavy in test 3 at the AREC
(Table 2). Resistance of lobelle, Guardian, and Florida Staysweet was about the
same. Wintergreen was much more damaged. Silverqueen was most severely damaged.
Table 2. Southern leaf blight, H. maydis, disease indices* of sweet corn
hybrids at harvest in 3 fall trials, 1978, Belle Glade area.
Test No. 1 2 3
Hybrids Date planted Sept. 15 Sept. 21 Sept. 21
lobelle 3.0 2.0 1.5
Guardian (XP370) 3.0 2.0 1.5
Silverqueen 4.0 4.0 3.5
Florida Staysweet 2.5 2.0 1.5
Wintergreen 3.5 3.0
* Disease index 0.5 slight to 5.0 very severe.
Yields from the three tests are presented in Table 3. Yields from test 1
were quite low and quality of ears poor. Good yields and quality of ears were
obtained from the other two tests with the best yields and ear length (Table 4)
being obtained in test 2. lobelle gave the highest yield in test 2 but this was
not significantly better than yields from Guardian or Florida Staysweet, There
was no difference in yields between Florida Staysweet and lobelle and yields of
both hybrids were higher than the other three hybrids at the AREC. Iobelle ears
averaged about an inch longer than Florida Staysweet in test 2 and about a half
inch longer in test 3. Florida Staysweet ears were comparable to those of
Silverqueen and Uintergreen in tests 2 and 3.
The commercial planting of Florida Staysweet in the field surrounding test
2 yielded 170 crates per acre of good quality ears.
From the results of these trials, it appears that Florida Staysweet can be
successfully grown in fall plantings in the Everglades area. Ear length of
Florida Staysweet was shorter than lobelle but satisfactory and comparable to
Silverqueen and Wintergreen. Yields of Florida Staysweet may be expected to be
comparable to those from Iobelle and equal or better than those from Guardian,
Wintergreen or Silverqueen.
Table 3. Yields in crates per acre of U.S. Fancy grade ears front sweet corn
hybrids in tests, fall, 1978, Belle Glade area.
Crates per acre*
Test No. 1 2 3
Hybrids Date seeded Sept. 15 Sept. 21 Sept. 21
Iobelle (104) 105 AB** 300 A 24' A
Guardian (XP 370) 50 BC 260 AB 125 C
Silverqueen 25 C 185 C 150 C
Florida Staysweet 160 A 235 ABC 250 A
Wintergreen 230 BC 160 B
* 5 dozen ears/crate.
** 1ieans having same letter are not significantly different according to Ouncan's
multiple Range Test (5% level).
Table 4. Average length of U.S. Fancy grade ears in inches from sweet corn
hybrids in tests, fall, 1978, Belle Glade area.
Test No. 1 2 3
Hybrids Date planted Sept. 15 Sept. 21 Sept. 21
Iobelle 7.4 A** 3.0 A 7.6 A
Guardian (XP 370) 7.0 A 7.6 AB 7.2 B
Silverqueen 6.9 A 6.9 C G.8 C
Florida Staysweet 7.1 A 7.1 BC 6.9 C
Wintergreen 7.4 ABC 6.8 C
** Means having same letter are not significantly different according to Duncan's
iiultiple Range Test (5% level).
FOR FLORIDA SWEET CORN*
Florida markets sweet corn during the fall, winter, and spring seasons. The
erratic behavior of sweet corn prices, and the degree of correlation that seems
to exist between prices and harvested acreage, have led growers to consider acreage
reduction policies in times of low prices. Such policy, however, does not always
lead to the maximization of total revenue.
Multiple regression was used to estimate the price-acreage relationship for
Florida sweet corn during the fall, winter, and spring seasons. Price-acreage
flexibilities and the corresponding price elasticities of demand were computed.
Data used covered the 1954-76 period.
Demand elasticity is a measure of the responsiveness of quantity demanded to
price changes. A straight-line demand curve (extended to both axes) has unitary
elasticity (e=l) at the midpoint, is elastic (e>l) above the midpoint, and in-
falls, total expenditures of consumers
remain the same, increase or fall when
demand elasticity is equal, greater, or Price
less than one, respectively. Revenues to
producers will therefore go in the same
direction. Since maximization of total e
revenue occurs at the point where e=l,
the Florida sweet corn industry ideally
would like to produce at that point. At
acreage levels greater than this, revenue
can be increased by restricting production
can be increased by expanding production. Harvested acreage
*This report summarizes a paper that will be submitted to the Florida State
Horticultural Society for possible presentation at this year's annual meeting.
JOSE ALVAREZ is Area Economist, Food and Resource Economics Department,
University of Florida, Agricultural Research and Education Center, Belle Glade.
Results show elasticity values of 5.11, 6.86, and 1.90 for the fall, winter,
and spring seasons, respectively. Therefore, the industry has been operating in
the elastic portion of the demand curve and could not have increased total
revenue by reducing harvested acreage during the period under consideration.
Furthermore, acreage reduction policies, while exerting an upward pressure on
prices, take producers away from the total revenue maximization objective.
V. L. ,uzman and T. A. Zitter
During the last season 433 breeding lines ,"ere evaluated, from which 663 plant
selections were made of the crisphead type, and 69 of the cos, leaf, an- butterhead
types. Seed increases in our facilities were made of S lines with a total of 1375
plants. Six lines were increased at Ferry-lorse Seed Co., 3 at Joseph Harris Seed
Co., and one at Cornell University. Seed increases of Fla. 12S0 at 'atzke and
Leach Farms in Berlin, '!isconsin were unsuccessful.
Crisphead types susceptible to lettuce mosaic virus (LIV). Florida Al is in
the process of being released. A tentative name suggested by Dr. G. Raleinh is
'Shawnee', after the farm where he made some of the selections for this outstanding
line. Lines Fla. 1255 and 13GG are also considered for release as soon as seed in-
creases are available. The fall commercial lettuce crop was severely damaged by
root rot, particularly in farms receiving heavy rainfall or when olantini was done
in vet soil. Transplanted' lettuce appeared to be more susceptible to the malady
than direct-seeded. 'iinetto' and 'Ithaca' are highly susceptible. 'Iontello' and
'Green Lake' are very tolerant to the malady and outyield the standard cultivars
where the disorder is present. 'lontello' and '"reen Lake', however, are highly
susceptible to rib cracking. Crosses made several years aqo were evaluated under
field conditions for resistance to root rot as well as for horticultural character-
istics (F4 propenies). Five lines involving crosses of ('Fulton' x 'ilinetto') x
'Creen Lake' showed promise and their seeds are being increased for further testing.
Another problem becoming more serious each year is downy mildew, cause by Iremia
lactucae Regel. So far as known, all our standard cultivars in Florida are sus-
ceptible. Attempts to identify tie race prevalent in Florida by Dr. n. Pieczarka
has met partial failure because of inadequate temperature facilities in the nrow'th
chambers. It is anticipated that after race iVentification, screening of all our
breeding material now available will be the first step toward production of resis-
tant cultivars to this disease.
Crisphead types resistant to LIV. The work continues with selections of Fla.
25060 an, Fla. 25042 for improvement of horticultural characteristics. The field
tolerance of these lines to L1V is excellent, but occasionally LIV symptoms develop
in the flowering stage. It appears that other workers in Europe an1 California had
the same problem. At this point it is not certain that seed from plants showing
L;V symptoms at the flowering stage transmit the virus.
Cos types resistant to LiV and bidens mottle virus ("i1V). One season testing
of Fla. 24069 in lettuce farms indicates that it performs similarly or better than
'Valmaine'. Fla. 24059 bolts about the same time as 'Valmaine' or after. In most
cases Fla. 24069 outyields 'Valmaine'. This line is resistant to LMV and BIlV but
susceptible to root rot.
3utterhead and leaf type lettuces. Crosses, selections and backcrossings
continue in an attempt to create a dark green butterhead and leaf lettuce resistant
to LIV and adapted to Florida's organic soils.
Belle Glade, AREC Research Report EV-1979-4 April, 1979
PRELIMINARY INVESTIGATIONS ON THE NUTRIENT REQUIREMENTS
OF CRISP-HEAD LETTUCE CULTIVARS
V. L. Guzman and R. E. Lucasl
The nutritional needs of head lettuce were investigated in the middle seventies
by Dr. H. W. Burdine. Based on his studies, fertilizer recommendations are made
from soil analyses. Since that time two new cultivars were released, Montello and
Green Lake, which are being grown due to their resistance to root rot. These two
outstanding cultivars, bred by Dr. Luis Sequira of the University of Wisconsin, are
well adapted to south Florida. However, both Montello and Green Lake are highly
susceptible to cracking of the rib and at times tend to produce heads too large for
the 24 head carton required by the trade. The intent of this report is to summarize
briefly part of the results obtained and to point out the similarities or differences
with respect to Minetto and Ithaca, the standard cultivars used in south Florida.
Montello and Green Lake are sister lines of a cross of Marquette x Fulton. It is
assumed that their nutritional requirements are similar. Iontello was used in this
Materials and Results
The first lettuce experiment (Exp. 700) followed sugarcane. The soil analysis
just after flooding gave a pH of 7.0, 3 lb P and 24 lb K. The soil samples were
taken when the soil was very wet which may have lowered considerably the P and K
content. The land received 4000 pounds per acre of sulfur and a month later the pH
was 5.6. The liquid fertilizer used was formulated to give 3 rates of P, and 3
rates of K in all possible combinations. The fertilizer was broadcast at the rate of
2000 Ib/A across the width of the field in a swath of about 30 feet, and several
four-bed plantings were made along the length of the field with Plinetto and flontello
seeds. Although the design was not randomized, it gave the opportunity of three
samplings across each treatment for each variety. Minetoo and Montello lettuce were
seeded on October 1 and harvested on December 4. Data in Table 1 report the results.
Even though the heads were small, there was no significant improvement in weight per
head or yield by the additional fertilizer over the 240 P205 and 240 K20 pound per
-/ Professor (Horticulturist) and Visiting Professor (Soil Scientist), Agricultural
Research and Education Center, Belle Glade, FL.
acre rate. Minetto outyielded-Montello by about 60 cwt per acre because Minetto
was more uniform and produced more marketable heads per acre.
Plant analyses were made on petioles at harvest. Some interesting results were
obtained when compared against Dr. Burdine's standards.
Plant Nutrient Ninetto Montello by Burdine
N percent 3.39 3.65 5.00
P 0.76 0.85 0.57
K 4.86 4.85 8.25
Ca 2.26 2.22 1.75
Mg 0.92 0.87 0.40
Cu ppm 5 6 10
Fe 80 79 --
fin 18 18 30
Zn 45 48 40
The standards of Dr. Burdine suggest the plants were low in nitrogen, potas-
sium, copper, very low in manganese and high in phosphorus, calcium and magnesium.
Of the two cultivars, Montello significantly had a higher nitrogen and phosphorus
content. Additions of 100 and 200 pounds of potash did not reflect in higher potas-
sium levels in the plant tissue. This certainly is hard to explain.
In the second experiment (702), two cultivars, Ithaca and Montello, were
planted in plots receiving 500, 750, 1000, 1500 and 2000 pounds per acre of 5-20-10
containing 0.24% Cu, 0.24% Zn and 0.02% B. The liquid fertilizer was applied in a
similar way to that used in Experiment 700, except that the plots were 60' in width
across the width of the field. This field was cropped to lettuce for the past six
years, flooded and 3000 pounds of sulfur per acre applied about one month before
Data in Table 2 show the results of the trial. Optimum yield was obtained at
about 1000 pounds of 5-20-10 fertilizer per acre for Montello and 1500 to 2000
pounds for Ithaca. Montello showed only slight root necrosis due to root rot, where-
as Ithaca showed severe damage. Despite the root conditions, Ithaca produced a good
crop. The fertilizer trial suggests that Ithaca requires higher nutrient levels
than Mlontello. In this trial, the difference may reflect the condition of the roots
Data in Table 3 report the results of the petiole analyses collected at harvest.
SThe design of Experiment 701 compared direct seeded and transplanted lettuce.
The cultivars were Ithaca, 1Minetto and Montello. In early December, soil tests were
made on each plot. They tested about 9 pounds of water soluble phosphorus and 80
pounds of 0.5 rN acetic acid extractable potassium per acre. The soil had.a pH of
6.7. Sulfur was applied at the rate of 2000 pounds per acre.
Phosphate fertilizer was applied at the rate-of 240, 380 and 540 pounds per
acre. This amount was estimated to raise the soil test to 20, 27 and 35 pounds per
acre, respectively. The actual soil tests at harvest were 43, 60 and 77 pounds per
acre (see Table 7). The potash was applied at the rate of 240, 340 and 440 pounds
per acre and was estimated to raise the soil. K test to 200, 250 and 300 pounds per
acre, respectively. The actual soil tests on January 12 were 152, 178 and 205
pounds per acre (see Table 8).
Nitrogen was applied on all plots at planting, time at the rate of 60 pounds
per acre. Sidedress treatments compared were 0, 20, 40 and 60 pounds per acre. The
experiment was designed so as to compare all possible combinations for the 4 nitro-
gen, 3 phosphate and 3 potash rates. Each combination was replicated 3 times.
The direct seeded lettuce was planted December 19 and on the same day seedings
were started in the greenhouse to grow transplants. These were planted in the field
21 days later January 10. The transplants gave nearly a perfect stand whereas the
direct seeded plants were thin because of wind-whipping.
Results of Experiment 701
Data in Table 4 report the average head weights and yields for direct seeded
cultivars. The nitrogen treatments show little effect on head weight but some in-
crease in yield. Thus, the number of marketable heads account for the difference.
Phosphorus significantly increased the weight per head. This Increase may be
due to earlier maturity. rlo doubt plants on low phosphorus treatments were a few
days behind in growth. As reported in Table 1 and Fig. 1, the weights were 1.93,
2.10, 2.15 and 2.18 pounds per head for 0, 240, 380 and 540 pounds of phosphate,
respectively. Yield differences are illustrated in Fig. 1, but less differences
were obtained when reporting yields as carton numbers. Potash had little effect on
head weight but yields were increased. This would again indicate more marketable
Data in Table 5 report the results for Ithaca and Montello transplants. The
transplanted lettuce out-yielded the direct seeded crop by 350 cartons per acre.
Weight per head was increased from 1.78 pounds for "0" phosphate to 2.05 pounds for
the 580 pound phosphate application. Potash did not show any head weight differ-
ences. Neither P nor K improved the number of cartons. However, as illustrated in
Fig. 2, the total weight was improved with phosphate fertilizer.
The cultivars show differences in the amount of crack-rib. The percent of the
heads showing the disorder were as follows: Minetto 62%; M.ontello 47%; and
Ithaca 34%. Much of the crack-rib was related to stage of maturity. 'linetto at
harvest was rated over-mature. lontello was considered mature and Ithaca slightly
immature. The effect of maturity was noted on rMontello, which showed 28% crack-rib
for somewhat immature heads and 52% four days later for mature heads. These results
support the practice of early harvesting of Montello to reduce crack-rib.
Brown rib, a disorder in lettuce, was present in some parts of the field.
Counts were made but they could not be associated with any particular plant nutrient
treatment. Ribby lettuce can be a cause for poor quality but was not rated in the
experiment. General observations seem to indicate better appearance with the higher
rates of nitrogen and phosphorus. Ribbiness is usually associated with adverse
weather conditions and/or low phosphorus levels. Root rot was not a major problem
in Experiment 701, but was present in :inetto and Ithaca.
Dollar Returns for Fertilizer
Many have shown that one should strive for about 95% of maximum production for
field crops. The additional expense of fertilizer for full production usually does
not give a profitable return. In the case of vegetables such as head lettuce, it
usually pays to obtain over 97 percent of the maximum production. Most field trials
cannot statistically evaluate yield differences of less than 3%. !e had the same
problem; nevertheless, average yields can give us some estimate on net return. Data
in Table 6 point out some economic returns. They suggest for winter arown crisphead
lettuce the use of 120 pounds of nitrogen, 380 pounds of phosphate and 340 pounds of
potash per acre which costs about $130 to $150 per acre.
A study of the yield (cartons) results for the transplant crop showed no bene-
fit from the application of P, K fertilizer. This in part may be due to the high
fertility level used in the transplant soil mix. Head weights, however, were im-
proved using phosphate fertilizer. Even increasing the phosphate rate from 240
pounds to 580 pounds per acre increased the:weight 0.12 pounds per head. For a
yield of 1100 cartons per acre:this amounts to 3170 additional pounds of lettuce.
The amount of P or K fertilizer needed for crops greatly depends upon residual
fertility. Dr. Burdine and others have suggested soil fertility levels of 30 pounds
of phosphorus and 200 pounds of potassium per acre. The site selected for Experi-
ment 701 was expected to show good response. Soil samples for each P, K plot were
collected Dec. 6 before fertilization, on Jan. 12 and at harvest time, Mar. 8. The
results of the soil tests for the check plots (no P or K added) indicated marked
changes'in pH and P for different sampling dates. This in part was due to the sul-
fur treatment. The soil tests,for the check plots were as follows:
Soil Sampling Soil Test
Date pH P K Soluble Salts
Dec. .6 6.7 9 81 640
Jan. 12 6.4 16 105 1320
Mlar. 8 6.2 22 37 1430
The pH change illustrates how the degree of soil acidity can easily affect the water
soluble phosphorus test.
A guide line used to estimate soil P changes is to apply 20 pounds of P205 to
increase the soil P test one pound per acre. For Experiment 701 calculations in
Table 7 show that about 10 pounds of P205 are required to increase the soil test one
pound which is low as compared to most studies. Similar calculations for.potassium
reported in Table 8 show a need of 4 or 5 pounds of K20 to change the soil test one
Some Past Soil Test Results;
Soils differ in chemical, physical properties. Unless we know the properties
of a specific soil, we still must rely on the results for a number of situations.
.Data in Table 9 show how P, K applications changed the soil tests for two other ex-
periments. Data in Table 10 show how soil acidity markedly affected the soil phos-
phorus test. This effect of acidity helps explain the results obtained for our
1. Lettuce planted in October had small heads. linetto outyielded Montello
by about 60 cwt per acre and had more uniform heads. Phosphate and potash applica-
tions greater than 240 pounds per acre did not show any significant improvement in
quality or yield. Plant analyses showed that Montello had a higher nitrogen and
phosphorus content in the petiole than the Minetto. The plant tests indicate low
nitrogen, potassium, copper and especially manganese.
2. A field trial comparing fertilizer rates showed that Ithaca required over
1500 pounds of a 5-20-10 while Montello required about 1000 pounds per acre. Root
rot was severe in the Ithaca but only light in the Montello. This root condition
may account for the difference in fertilizer requirement for the two cultivars.
Tissue analyses showed that Montello roots had a higher phosphorus content than the
3. Trnasplanted lettuce outyielded direct seeded lettuce by about 350 cartons
per acre. Lower yields in the direct seeded crop were caused by "wind whip" which
reduced stands. In the fertilizer trial the major response was an increase in
weights per head from the phosphorus addition. For direct seeded lettuce the weights
were 1.93, 2.09, 2.14 and 2.18 pounds per head for 0, 240, 380 and 540 pounds of
phosphate per acre, respectively. Similar comparisons for transplants were 1.78,
1.93, 2.00 and 2.05 pounds per head.
4. Soil tests after flooding show nearly neutral soil reaction (pH 6.7 6.8)
and tested low in available phosphorus and potassium. After a few weeks and on ad-
dition of sulfur the water soluble phosphorus test increased markedly. This change
in the test makes it difficult to estimate the phosphorus fertilizer requirements
In general, the guideline of 30 pounds of water soluble phosphorus and 200
pounds of weak acetic acid extractable potassium as ample amounts of P and K for
head lettuce appears to be supported by the field trials in 1978-79.
Cracked rib was high in both Minetto and Montello. i1inetto, however, was over
mature when crack rib ratings were made. Root rot was not a problem in the early
Table 1. The effect of P-K fertilizer on weight and yield of lettuce planted
in October (Exp. 700).
Fertilizer Pounds per head Yield cwt/acre
per acre iNi netto lontello Minetto Montello
240l/ 1.6 1.9 330 240
380 1.6 1.7 317 255
540 1.7 1.7 303 275
2401/ 1.6 1.8 323 265
340 1.7 1.7 310 254
440 1.7 1.7 317 241
1/ Soil test at harvest time: pH 5.6; P 24; K 70.
Table 2. Effect of different rates of a 5-20-10 on yield of Ithaca and Mlontello
head lettuce planted November 28 and harvested February 13 (Exp. 702).
5-20-10 Ithaca lontello-/
Lbs/A Heads/A Cwt/TA Lb/Head Heads/A Cut/A Lb/Head
500 10200 199 2.0 13100 243 1.8
750 10700 189 1.8 15000 266 1.8
1000 11600 246 2.1 14000 268 1.9
1500 13500 276 2.0 13100 258 1.9
2000 12600 270 2.2 11600 223 1.9
[lean 11600 236 2.0 13100 251 1.9
I/ Slightly immature with about 5% of the heads showing cracked ribs.
Table 3. Tissue nutrient content at harvest of
organic soil with 3 fertilizer rates,
2 lettuce cultivars grown in
Fertilizer Percent PP"
Lb/A N P K Ca Iig Cu Fe ;in Zn
Table 4. Effects of [I-P-K fertilizers on weight and yield of direct seeded head
lettuce (Exp. 701).
Lbs/Acre Ithaca Minetto i ontello Average
------------------- ---Pounds per head ----------------------
YIELD Cartons per acre (by number)
I/ Weight for the zero P205, and zero
Difference mostly due to the
Table 5. Effects of P, K fertilizer on
weight and yield of transplanted lettuce.
Lbs/A Ithaca .ntil)o Average
Pounds per Head
1/ The check plot no phosphate, no potash added.
Table 6. Return from fertilizer for direct seeded head lettuce.
Pounds/Acre Cost/Acre Value Increase-/ $ Net
N Nitrogen 0 184/Lb4/
60 $ 10.80
80 14.40 + 2.002/ 2.003 14.40
100 18.00 + 2.00 32.00 12.00
120 21.60 + 2.00 44.00 20.40
P205 Phosphate 0 20t/Lb5/
240 $ 48.00 78.00 30.00
380 76.00 136.00 60.00
540 108.00 120.00 12.00
K20 Potash 0 9t/Lb/
240 21.60 44.00 22.40
340 30.60 146.00 115.40
440 39.60 140.00 100.40
1/ Head lettuce valued at $2.00 per carton standing in the field.
2/ $2.00 cost for application.
3/ See Table 4 for yield increase.
4/ Assumes 380 Ibs. P205 and 340 Ibs. of K20 applied.
5/ Assumes 90 Ibs. r1 and 340 Ibs. of K20 applied.
6/ Assumes 90 Ibs. N and 380 Ibs. of P205 applied.
Table 7. Changes in soil P test as related to the amount of phosphate applied
Soil Sampling Pounds P205 Applied/Acre
Date 0 240 380 540
Soil P Test Lb/Acre
Dec. 6 9 -- -- --
Jan. 12 15 32 40+ 40+
i;ar. 8 22 43 60 77
Amount of P205 fertilizer to change soil P test 1 lb.
Dec. 6 "9" test 7 7.5 8
Ilar. 8 "22" test 11 10 10
Table 8. Changes in the soil K test as related to the amount of potash applied
Soil Sampling Pounds K20 Applied/Acre
U 240 340 440
Soil K Test Lbs/Acre
Dec. 6 81 -- -- -
Jan. 12 105 152 178 205
[Mar. 8 37 127 151 105
Amount of (20 fertilizer to change soil K test 1 pound
Jan. 12 "81" test 3.4 3.5 3.5
"105" test 5.1 4.7 4.4
;mar. 8 "81" test 5.2 4.9 5.4
"87" test 6.0 5.3 5.6
Table 9. Soil test changes as
phosphate and potash application (data
Fertilizer applied Fertilizer required to increase
Lb./Acre Soil Test the soil test 1 pound
Table 10. Effect of pH on the amount of water soluble phosphorus.
A. A Sandy Mluck Currin Farm (1970-71)
B. Organic Soil at the Research Center
pH P Test
C. Duda Farm (1970-71)
Sulfur (4500 lb/A)
D. Okeelanta Peaty luck 1950 report by U. T. Forsee
% P in Celery
y L. -
~, i C)
L F TTUC&FZ
-~r P(DLj 1L u PC. PPfA
L E TT UC
T (r"j~iSPLtF nrTS
:iRTOn3 PF R gCRE
f~7~( i)~ -POuF~D5 P6K PWP
p j3< I
R. E. Lucas1
Liquid fertilizers have been marketed for several decades. Still, many
users do not know the difference between liquid and dry fertilizers and many
costly mistakes have been made. This bulletin should answer some of the
problems occurring with liquid fertilizers.
What are Liquid Fertilizers?
Any liquid that contains one or more available plant nutrients is a
liquid fertilizer. The plant nutrients may either be in complete solution
or part in solution and part in suspension.
The main advantage of liquid fertilizer is greater ease of handling and
applying. Liquids permit more uniform application. The produce is more uni-
form in analysis. Certain pesticides are compatible. Thus "weed and feed"
programs are possible.
Liquid fertilizers require special storage tanks, pumps and hoppers
which can greatly add to costs. Salting out in cold weather can also occur.
Adding micro-nutrients and magnesium often creates a problem of sedimenta-
tion. Picronutrient chelates and polyphosphate materials have overcome some
of the problems. Complete H-P-K fertilizers, especially those containing
micronutrients, contain relatively low plant-nutrient content.
Availability to Plants
Nearly all the active ingredients in liquid or dry fertilizers commonly sold
are water- or citrate-soluble. Thus, they are equally available for plants.
Although the fertilizer salt may be 100% water soluble, there may be a rapid
change to compounds of low water solubility after application to the soil.
For example, a liquid fertilizer containing 100,000 ppm of phosphorus will
likely test no more than 0.3 ppm in the soil solution after application.
Residues from Dry Fertilizers
Liquid fertilizers seldom show any residues in the soil when band-placed
as do many dry fertilizers. This residue should never be cited as an example
of poor recovery for dry fertilizers. These residues are usually conditioners,
inert materials, by-produces such as gypsum and impurities. Some of these
residues may be calcium, magnesium or sulfur which are essential plant nu-
trients for which no claim has been made. If such materials were added to
liquid fertilizers they would normally cause sedimentation.
All mineral fertilizers can cause injury to plants when applied in ex-
cess. Unless diluted with water, most liquids of comparable formulation are
as toxic as dry fertilizers. Fertilizers can show differences in burn which
are measured by a "salt index." This index is compared against an equal
weight of sodium nitrate. The salt index for some common fertilizers:
Salt Salt Index
potassium chloride 116
ammonium nitrate 105
sodium nitrate 100
potassium nitrate 74
ammonium sulfate 69
calcium nitrate 65
potassium sulfate 46
superphosphate (0-46-0) 10
mono potassium phosphate 8
diammonium phosphate 31
*From Rader et. al. Soil Sci. 55:201-218
Liquid fertilizers made specifically for application to the foliage of
plants, on the seed, or for household plants, should have a low salt index
value. Double nutrient salts such as ammonium phosphate and mono potassium
phosphate help keep the salt index down. Additional information about types,
uses and characteristics of fertilizer can be found in Michigan State Univer-
sity Extension Bulletin E-896.
By the Gallon or by 'Jeight?
Most liquid fertilizer concentrates weigh 10 to 11 pounds per gallon.
Thus it takes about 9 gallons of liquid to compare to 100 pounds of dry fer-
tilizer. If the dry fertilizer costs $9.00 per hundred (180P.00 per ton),
then you should be on guard if the liquid fertilizer of the same formulation
costs more than $1.00 per gallon. Fertilizers of the same grade, formula-
tion, placement and rates give nearly identical response whether liquid or
Fertilizer with the Seed
Either dry or liquid fertilizers can be applied with the seed at planting
time. Row spacing, soil moisture conditions and type of seed greatly modify
the amount that can be applied. If in doubt, do not follow the practice.
Dry soil accentuates the problem. For wheat and other small grains planted
in moist soil and in 7-inch rows, apply up to about 100 pounds of plant nu-
trients per acre (N + P205 + K20). For field corn planted in 38-inch rows,
the upper limit is about 15 pounds. Beans, soybeans, cucumbers and melons
are very sensitive to salt injury. Do not use fertilizer applied on the
seed for these crops.
Some vegetable crops such as spinach, red beets, tomatoes and onions
can benefit from a small amount of a high phosphate fertilizer placed in the
same band as the seed, especially when the soil is cold. A suggested ma-
terial is 10-34-0 at 5 to 10 gallons per acre for 12-inch row spacing or 2
to 3 gallons for 36-inch row spacing. Use the lower rate for sandy soils
since they likely contain less water. Solutions such as 10-3^-0 are usually
diluted four or more times with water to help reduce salt intensity and to
give a more uniform application.
Fertilizers on or near the seed are more likely to benefit snall seeds
than large seeds such as corn and beans. The salt-index value of the various
solutions need to be considered when applying fertilizer on the seed.
Liquid Nitrogen Fertilizers
Anhydrous ammonia and certain liquid ammonia solutions need to be in-
jected into the soil to prevent ammonia losses. Hater mixtures containing
ammonium nitrate and urea (2R to 32% N) are popular products, competitively
priced, and can be rapidly applied broadcast. Hov'ever, follow the recom-
mended practices to prevent urea volatilization, whether applied dry or in
a liquid solution. Losses are greatest when: urea is applied to dry sur-
faces, the soil temperature is high and the soil is above pH 7.0. To
reduce losses, water the urea into the soil or apply into the moist soil.
Plant nutrients can be absorbed through the leaves, but the amount that
can be applied without burn is limited! The minimum nutrient requirements
for plants are rather specific regardless of the method of application. Thus,
do not expect any benefit from leaf feeding or any other program if the plant
already has ample amounts. For example, ample nutrient levels for corn ear
leaves at silking time are about 3.0% nitrogen, 0.3% phosphorus and 1.75
potassium. Plants will take up additional nutrients but without any in-
crease in yield. Ile sometimes call this situation "luxury feeding."
Leaf feeding can be used to good advantage where spray programs are
necessary for pest control and the fertilizer material is compatible. The
practice of applying only the major plant nutrients (N-P-K) by leaf feeding
generally gives poor returns because of the relative high energy and labor
costs per unit of plant nutrient applied. Extra field trips also increase
soil compaction problems. Thus, leaf feeding should be considered a supple-
ment to, not a substitute for, the regular soil application of fertilizers.
licronutrients such as manganese, zinc, copper, iron, boron and moly-
denum can be applied by leaf feeding because of the small amounts required
for normal plant growth. In comparison to that needed by soil application,
the amounts are greatly reduced for leaf feeding. See Table 11, M1SU Exten-
sion Bulletin E-486, for the suggested rates and sources of secondary and
micronutrients used for leaf application.
Liquid fertilizers are often used to make starter solutions for trans-
plants. The fertilizers in solution are immediately absorbed. This
promotes new growth and better plant survival. There are also many all-
soluble dry fertilizers which can be used in starter solutions. To prevent
clbudiness, use soft or low-lime water. Rain water or distilled water is
best for making a concentrated starter solution from dry fertilizers.
The maximum amount of fertilizer in a starter solution will depend upon
the carriers. Follow the manufacturer's recommendations. Normally, 5 to 8
pounds of the all-soluble dry fertilizer are added to 100 gallons of water.
Concentrated liquid fertilizers such as 10-34-0, 10-20-10, etc. are diluted
100 to 150 times by volume. The starter solution is applied directly to
the transplant at the rate of one-half pint per plant. Extension Folder
F-194 "Starter Solution" illustrates some good formulations that can be
Fertilizers through the Irrigation System
Flitrogation or fertigation are terms sometimes used to describe the
application of nitrogen or other fertilizer nutrients through the irriga-
tion system. The most common fertilizer applied is 23% nitrogen solution
because it is easily obtained and causes little or no problems when added
to the water. All soluble dry products such as urea, ammonium nitrate
and potassium nitrate can be dissolved in water and then metered into the
irrigation system. Anhydrous ammonia, phosphate materials and aqua ammonia
should not be applied through an irrigation system because of precipitation
problems and losses of ammonia into the air during application.
The amount of nitrogen that can be applied through the irrigation sys-
tem is limited only to the capacity of the injector pump. Even with a
high rate of injection, the nitrogen will be so dilute that it will seldom
cause injury to crops. Most situations call for rates of 20 to 50 pounds
of nitrogen per acre per application. Additional information on this method
of application can be obtained in a mimeo prepared by F. L. Vitosh of the
Crop and Soil Sciences Department, MSU.
Many greenhouse operators and vegetable growers are equipped to apply
fertilizer through their watering system. They generally make up a con-
centrate solution and dilute with an injector 100 to 300 tines with the
water. rlany strive for a final concentration of about 100 ppm nitrogen
in the water. Twenty ounces of 20% nitrogen fertilizer added to one gal-
lon of solution and then injected into the water at a ratio of 1 to 200
will make a final solution containing 150 ppm nitrogen.
Nutrients in One Gallon
As already mentioned, a gallon of liquid fertilizer weighs, at most,
about 11 pounds. Thus, a gallon of 5-20-5 analysis has about pound of
nitrogen, 2 pounds of phosphate and pound of potash. Except possibly
for a starter benefit, do not expect wonders from a few gallons per acre.
In midseason, rapidly growing crops such as corn will take up daily 4 to
7 pounds of plant nutrients per acre. The total nutrient uptake for a
130 bushel corn crop is about 175 pounds of nitrogen, 70 pounds of phos-
phate and 160 pounds of potash. There are products on the market which
are recommended at rates of only 1 to 2 quarts of NI-P-K fertilizer per
acre. Obviously, this is not enough to meet the crop needs. A good
fertilizer program takes into account the plant nutrient uptake of the
crop, the soil test and the expected return.
Extension Bulletin E-933, January 1976
Cooperative Extension Service, Michigan State University
SEED PRIMING TO OVERCOME THERRODORIIAfICY IN LETTUCE DURING GERiIIATION
A. C. Guedes and D. J. Cantliffe
Vegetable Crops Department, University of Florida, Gainesville
Florida Lettuce, Inc., South Bay
K. D. Shuler
Extension Agent, Palm Beach County, Belle Glade
As soil temperatures rise above 30C (830F), lettuce seed becomes dormant
(thermodormancy). Many seed treatments have been used in an attempt to overcome
thermodormancy. They include application of growth regulators, such as kinetin,
ethephon, ethylene, thiourea, humic acid and fusicoccin, increased oxygen or carbon
dioxide levels, or removal of the seed coat. These treatments have generally been
quite successful in allowing lettuce seed to germinate at 350C under laboratory
conditions. Unfortunately, when these same treatments were used in the field they
During hot weather in California, where some 220,000 acres of head lettuce is
grown annually, lettuce seed is planted in dry soil then irrigated in the early
evening. The seed imbibes water when the temperatures are lower at night. As soil
temperatures rise again the next day the "dormancy block" has already been bypassed.
This method of overcoming thermodormancy is not possible in Florida, where soil
temperatures remain constantly high, day and ninht, in the late summer.
Recently, new techniques have been developed whereby seed is soaked in an os-
motic solution which restricts the amount of available water to the seed. Ry al-
tering the temperature and-the amount of time that the seed stays in contact with
the soak solution a seed can be brought to the brink of radicle emergence. This
process is called seed priming.
"e felt that if lettuce seed could be properly primed, the termination block
which leads to thermodormancy might be bypassed. Laboratory experiments using the
lettuce cultivars 'Hinetto', 'lesa 659' and 'Ithaca' were primed at temperatures of
5, 150 and 25C in various concentrations of polyethylene glycol 6000 (PEG), potas-
sium phosphate (K3PO4) or water alone. VIhen the seeds were imbibed in the labora-
tory at 35C in petri dishes or soil, termination occurred only in the primed seed
treatments. The highest percentage germination occurred when the seeds were soaked
in 1% K3PO4 for 9 hours in the light and the seeds were air dried after treatment.
Germination of primed lettuce seed at 35C, in normal laboratory tests.
Cultivar Control Hater K3PO4 PER K3P
Minetto Od 59b 71a 9c 35b
Ithaca Od 33b 49a 13c 33b
Mesa 659 Oc 41b 58ab 55b 68a
ilaximum germination varied between cultivars, however, in several laboratory
tests termination percentages exceeding 90 were obtained.
Similar tests were conducted in Palm Beach County with Florida Lettuce, Inc.,
in a commercial planting on muck soil. The experiment was planted on September 20,
1978, when maximum day temperatures were 3"C and minimum night temperatures were
21C. Soil temperatures were not high enough to induce thermodormancy in 'Iinetto',
'Ithaca' and a line 7423-4; however, primed seed geminated more rapidly than the
A romaine type of lettuce ('Valmaine') was observed to be very sensitive to
high temperature during germination. "!hen the temperature for termination was
raised from 250 to 30C control seeds did not germinate, while primed seeds did but
at a decreased percentage. In a field test with Florida Lettuce, Inc., under simi-
lar conditions as the previous experiment, emergence of 'Valmaine' was higher with
primed seeds than the control. Only 50% of the untreated seeds emerged while 30%
of primed seeds emerged. Seed priming significantly advanced the crop's commercial
From these experiments it was determined that thermodormancy of lettuce in the
field can be overcome by seed priming. The priminn conditions for maximum qermina-
tion may have to be determined for each seed lot, however, a soak of 1% KPO in th
light for 9 hours with aeration generally led to between GO and 70% emergence.
Further studies will be conducted to determine the benefits of lettuce seed priminn
under more extreme temperature conditions.
Belle Glade AREC Research Report EV-1979-6 May 1979
PRELIMINARY REPORT ONI MESUROLR TO REPEL BIRDS FROM PULLING
SEEDLING RICE PLANTS
U. G. Genung and G. H. Snyder1/
Bird damage to corn, rice and other grain seedlings is so well documented we
could not begin to list the citations here. The principle species involved in this
damage in the south have been the red-winged blackbird (Agelaius phoeniceus), boat-
tailed grackle (Cassidix mexicanus), common grackle (Quiscalus quiscula), brown-
headed cowbird (Molothrus ater), starling (Sturnus vulgaris), house (English)
sparrow (Passer domesticus) and to some extent the meadowlark (Sturnella magna),
Beal (1948), Genung and Green (1974), Genung, et al. (1976), Green (1973), Neff and
Meanly (1957) and Meanly (1971).
During the present spring we observed the most complete destruction of rice
seedlings we have ever seen in the Everglades, 60 acres of rice completely destroyed
to nearly destroyed on one farm, mainly by red-winged blackbirds. Since these large
flocks were composed mainly (90%) of males, we assumed these were mostly migrant
rather than local race(s). The fields that sustained the greatest damage were ad-
jacent to favorable roosting and resting areas.
With the resurgence of a rice industry in the Everglades, Alvarez (1978) and
Snyder, et al. (1977), after a Federal ban of nearly two decades (due to presence
of Hoja blanca (white leaf) virus disease and its delphacid vector (Sogata
orizicola), Green and Panzer (1958) it appeared that an acute bird problem might
threaten a return of this promising industry. At the same time we are, and have
long been on record as cognizant of the importance of birds in the natural control
of major insect pests, Hayslip, etal.(1953), Genung and Green (1974), Genung, et al.
1/Professor (Entomologist) and Associate Professor (Soil Chemist), respectively,
Agricultural Research and Education Center, Belle Glade, Florida.
Today the utilization and husbanding of all the beneficial fauna arayable
against injurious insects is even more important than in the recent past decades,
due to insecticidal resistance, insecticidal restrictions, and use cancellations.
This concept is an equal factor with judicious use of pesticides, cultural prac-
tices, and pest resistant varieties in integrated pest management systems. Our
advocacy of alternatives to destructive bird control and expressed desire for ef-
fective and harmless bird repellents is documented (1974, 1976) and is in
recognition of the great capacity of birds for good in Florida agriculture.
The bird species that cause the greatest damage to crops are also among those
of great potential value to agriculture because they are highly insectivorous, occur
in large numbers, have great mobility that enables them to assemble at points of
heavy insect infestation, and have a great feeding capacity that is immensely en-
hanced during the nesting season since the young icterids are fed almost entirely
on insects. It is hoped that the use of recently developed bird repellents can
greatly reduce bird damage in the few susceptible crops and enable us to take fuller
advantage of their beneficial attributes. Herein we report on our preliminary
trials with Mesurol used in various formulations and different application methods.
resurolR, 3, 5 Dimethyl-4-methylthiophenol methylcarbamate2/, is an insecti-
cide molluscicide that has strong bird repellent properties. This material has
clearance as a repellent for sprout pulling blackbirds in the east and for birds
attacking cherries in Michigan (1977).
Investigations of mesurol (methiocarb) by various agencies, on a wide range
of bird susceptible crops, bird species, and continental areas, Herman and Kolle
(1971), Guarino (1972) and Crase and DeHaven (1976), Mottet al (1976)'have geh-
erally indicated considerable effectiveness in bird repellency.
Materials and rMethods
The trials in each case were unreplicated, 1/5 acre comparisons of Mesurol
treatments with an untreated check of the same size. As shown in Figure 1, the
experimental area and its adjacent lands was unusually uniform and one would expect
approximately uniform bird invasion of treatment and check unless a repellent factor
intervened. The distance between treatments and checks was at least 100 to 150
2/Supplied by Mobay Chemical Corporation, Agricultural Chemicals Division, Kansas
Experiment 1: It was theorized that if the birds would accept a bait placed
in well exposed stations prior to rice germination that this might reduce material
amounts and be even more economical than overall seed treatment. Cracked corn bait
stations were scattered through the treatment plot prior toseedling emergence.
The cracked corn was treated at a rate of lb. 75% seed treatment/100 lbs. of seed.
Experiment 2: iesurolR 75% P spray was applied to the treatment area after
emergence of the rice plants at 2.00 Ibs/active-ingredient/acre. Nlo material was
applied in the check area.
Experiment 3:. Rice seed was treated with.k lb 75% MesurolR seed treatment/100
lab of rice seed, The seed were planted with a grain drill. A similar untreated
planting was made 100 yards north of the treated plot, Figure 1i Observations on
effectiveness were commenced with rice seedling germination.
Experiment 1: In this case the cracked corn bait did not appear to attract
birds, possibly suggesting that when used in this way smaller amounts of the active
ingredient would be required. After emergence of rice 89 plants were destroyed in
the treated area, 44 in the check. No bird mortality was observed in or around the
Experiment 2: Apparently we delayed too long before mesurol HP application
was made and the rice seedlings in both the treatment and check had ceased to be
desirable to the birds. No bird mortality could be observed in or around the ex-
Experiment 3: Observations were made at daily intervals at first sign of ger-
mination, except during a day of heavy and continuous rain. Figure 1 gives the
cumulative count of pulled plants, the bird species and numbers observed in the
plots, and shows the general locale of the test. There were 16 times as many
pulled plants in the check as compared with the mesurol seed treatment. It appears
quite significant that all damage in the treatments was marginal whereas that in
the check occurred throughout the plot. Boat-tailed grackles and meadowlarks were
frequently observed working in the check for prolonged periods, but only 2 grackles
were observed, briefly in the treatment. Killdeers, (Charadrius vociferus) observed
in both treatment and check would not be expected to have any significant contact
with treated plant material. The mourning doves (Zenaida macroura) and savannah
sparrow, (Passerculus sandwichensis) observed only in the check were probably feed-
ing only on the exposed or wasted seed. The northern mockingbird (Mimus poly-
glottos) would not be expected to feed on this type of plant material. Neither the
lesser yellowlegs (Tringa flavipes) nor solitary sandpiper (Tringa solitaria) are
deemed likely to make significant contact with mesurol treatment. 'No bird mortality
was observed in or around the experimental area.
'lesurol seed treatment in a preliminary test looked exceptionally good in pro-
tecting rice seedlings from being pulled by birds. A protective period of about
a week is required following germination. We feel that although the bait treatment
was not effective, that both it and a better timed seedling topical application are
worthy of further testing. Possibly a more acceptable bait (rice?) or reduced
amounts of the repellent would give better results since the stationed bait would
not be acted upon by the soil or germination and growth processes. We were pleased
that no ev idence of bird mortality occurred in any of the experiments. Possibly
continued development and use research on compounds of this nature will result in
broader protection of susceptible crops from excessive bird damage without resort
to destructive bird control techniques, and thus permit the fuller utilization of
this natural insect control resource.
Alvarez, J. 1978. Potential for commercial rice production in the,Everglades.
Ec. Information Rept. 98, Food.and Resource Economics-Dept., Agr. Exp..
Stations, IFAS, University of Florida.
Anonymous-1977. Pesticide roundup. Farm Chemicals 40(1):44.
Beal, F. E. L. 1948. Common birds useful to the farmer. USDI, Conservation
Bull. 18, USDI, Fish and Wildlife Service.
Case, F. T. and R. H. DeHaven. 1976. VMethiocarb: its current status as a
brief repellent. Proc. Seventh Vertabrate Pest Conference. 46-50.
Genung, W. G. and V. F. Green, Jr. 1974. Food habits of the meadowlark in
the Everglades in relation to agriculture. Environ. Entomol. 3(1):39-42,
Genung 11. G., fl. J. Janes, and V. E. Green, Jr. Insects and other dietary
items of Maynard's red-winged ~blackbird in relation to agriculture. The
Fla. Entomol. 59(3):309-16.
Green,'Jr., V. E. 1973. Birds injurious to the world rice crop. 1 part 2,
Western hemisphere. Revista i1 Riso Anno. XXII, n. I. 59-68.
Green, Jr., V. E. and Panzer, J. D. 1958. "Hoja Blanca" How, the disease was
discovered in Florida. The Rice Journal 61:16-26.
Guarino, J. L. 1972. Methiocarb a chemical bird repellent a review of its
effectiveness on crops. Proc. Fifth Vertabrate Pest Conference. 108-111.
Hayslip, N. C., H. G. Genung, E. G. Kelsheimer and J. %. Uilson. 1953.
Insects attacking cabbage and other crucifers in Florida. Univ. of Fla.,
Agr. Exp. Stas. Bull 534.
Herman, G. and !. Kolbe. 1971. Effect of Seed Coating with R'esurol for
protection of seed and sprouting maize against bird damage with considera-
tion to varietal tolerance and side-effects. Pflanzenschutz nachrichten.
Meanly, B. 1971. Blackbirds and the Southern Rice Crops. Resource Pub. 100
USDI, Fish and Uildlife Service, BSFU.
[iott, D. F., J. L. Guarino, E. W. Schafer, Jr. and D. J. Cunningham. 1976.
Methiocarb for preventing blackbird damage to sprouting rice. Proc.
Seventh Vertabrate Pest Conference. 22-25.
Pleff, J. A. and B. Meanly. 1957. Blackbirds and the Arkansas rice crop.
Univ. of Arkansas, Agr. Exp. Sta. Bull. 584.
Snyder, G. H., J. Alvarez, J. U. rishoe, D. L. rIyhre, S. F. Shih and V. E. '"'
Green, Jr. 1977. The Economic Potential for Incorporationing Rice in
Everglades Vegetable Production Systems. Proc. Fla. State Hort. Soc.
:r uuuxt' I.-
SEED TREATMENT EXPERIMENT
FALLOW FIELD (Weedsand Grasses)
7 2 1 PULLED-RICE PLANTS 45
Birds below dotted lines
No bird mortality observed in and
around the experiment area
4 B.T. GRACKLES
4 MDW. LARKS
2 R.W. BLACK BIRDS
I SV. SPARROW
I SOL. SANDPIPER
:; seed i
: :treat~m. ::
;: 1/5A ::
;*;*;*'**** ;* ;;;;
;; : :; :;
PASTURE (ST. Augustinegrass)
(Not to Scale)
SUMMARY OF RESEARCH OH RHIZOCTONIA ROOT ROT
AND STALK ROT OF CELERY
D. J. Pieczarka
Root rot In 1977 it was determined that a root rot of celery seedlings in
commercial seedbeds was caused by Rhizoctonia solani. Studies since that time
have indicated that the celery varieties Florimart, Earlibelle, June-Belle, Florida
2-14, Florida 683 and breeding lines 1624 and 2192 were equally susceptible to
Rhizoctonia root rot when tested under greenhouse conditions. In the field, tests
were conducted to determine the influence of plant densities and the addition or
removal of toppings on root rot severity. In three experiments testing the
influence of plant densities which included 20, 40, 60, 80 and 100 seedlings per
sq. ft., there were no differences in the severity of Rhizoctonia root rot between
treatments. The addition or removal of toppings from seedbeds also had no apparent
influence on root rot development
In chemical control trials for root rot the following replicated and randomized
fungicide treatments were tested in celery seedbeds as drenches: Dithane 1-45 (3
Ibs/A), Kocide 101 (3 Ibs/A), Benlate (1 Ib/A), Benlate + Dithane 11-45 (1 + 3 Ibs/
A). Benlate + Difolatan (1 lb + 6 qts/A), Bravo 6F (2 pts/A) and Difolatan 4F (6
qts/A). In an additional treatment Terraclor Super-X granular was applied as a
single application when the seedlings were 3 weeks old. The fungicide.drenches
were applied once weekly (in 1 gal of water/40 sq.ft.) starting when the seedlings
were 3 weeks old. A total of 9 drench applications were made before the seedlings
were pulled and rated for root rot. In the control (no fungicide drench) 9% of the
plants sampled exhibited root rot symptoms. Significantly less root rot developed
in the Bravo, Kocide, Benlate + Difolatan and Difolatan treated plots only, and the
corresponding percentage of infected plants was 5.8, 5.2, 4.7 and 4.3.
Stalk Rot An intensified study on the epidemiology and control of Rhizoctonia
stalk rot of celery was initiated in the fall of 1978. The goals of this study are
to better understand the disease and to develop an effective scouting procedure
that would assist in controlling stalk rot with minimal and timely use of fungi-
cides. In September, 1978, a field experiment was conducted to trace the develop-
ment of stalk rot and compare fungicide control programs based on scouting with
preventive spray programs started at week 1 and 6 after transplanting.
Disease free seedlings of the celery variety 'Florida 2-14' were transplanted
on September 19-20, 1978. Fungicide treatments commenced on Sept. 25 and were con-
tinued mainly on a 4 to 5 day schedule until Dec. 6, 197,. A total of 19 fungicide
applications were made. Each treatment was replicated A tines in a randomized com-
plete block design. Spray applications were made with a motorized sprayer operated
at 100 psi and equipped with over-the-row and drop nozzles. The fungicides used
were Manzate 200 (1.5 lbs/A) and Benlate (.75 lbs/A). withinn 14 days before har-
vest Kocide (1.5 lbs/A) was substituted for Manzate. The treatments consisted of:
1) Control, no fungicides
2) Manzate only
3) Manzate only, but when scouting revealed that stalk rot was
developing Manzate + Benlate was applied
4) Manzate up to week 6 after transplanting, but Manzate +
5) Manzate + 3enlate
In treatment 2-5 Manzate was used alone on a 4-5 day preventive spray schedule
to control early blight. Manzate + Benlate was used for controlling stalk rot
because this combination was shown to be very effective in controlling the disease
(J. 0. Strandberq, unpublished data). During the duration of the experiment, plots
were scouted weekly by destructively sampling 16 plants per treatment and deter-
mining the extent of stalk rot damage. withinn 1 week after transplanting lesions
were evident on outer petioles. In all treatments stalk rot developed slowly during
the first 6 weeks after planting. At week 7 and 8 there was a significant increase
in the number of petioles infected per plant in treatments 1, 2 and 3. In treat-
ments 4 and 5 (preventive control for stalk rot) the number of infected petioles
per plant remained low. In treatment 3, four fungicide sprays (2 Manzate +
Benlate, 2 Kocide + Benlate) were applied to control stalk rot. These were ap-
plied on NIov. 17, Nov. 22, Dec. 2, and Dec. G. The first application was based on
the appearance of lesions on larger petioles that would possibly be part of the
marketable stalk. Subsequent fungicide applications were based on further develop-
ment of the disease as determined by scouting. After the second application of
ianzate + Benlate there was a reduction in the number of petioles infected per
stalk. This resulted from a loss of petioles due to senescence and a reduction
(control) in disease development. At harvest, treatment 3 (scouting) provided
yields similar to those from treatments 4 and 5 (preventive spray programs) where
only light petiole stripping was necessary because of stalk rot damage, resulting
in limited yield loss (Table 1). In the control and Manzate only treatments con-
siderable stripping was necessary (2.9 and 1.6 petioles per plant, respectively)
resulting in significant yield loss on a weight basis (Table 1). Therefore, fungi-
cide applications for stalk rot control, based on weekly scouting for disease de-
velopment, resulted in fewer fungicide applications and disease control was similar
to treatments with a preventive spray program started 1 or 6 weeks after planting.
Experiments are currently under way to more accurately define stalk rot
scouting procedures and factors influencing development of the disease. In addi-
tion, cultural control measures are being investigated as well as other fungicides
and fungicide combinations for stalk rot control.
Table 1. Rhizoctonia damage to marketable petioles at harvest.
Infected petioles Reduction in stalk
Treatment per stalk wt. due to stripping
No fungicides 2.9 A 45% A
started week 1 .6 B T6%
Hlanzate + Benlateb
+ scouting 0.6 C 6% C
?lanzate + Benlatec
started week 6 0.6 C 6% C
Manzate + Benlate
started week 1 0.6S C C% C
a Four to 5 day spray schedule.
See text for rates.
u Two sprays of fanzate + Senlate applied at week 8 and 9 (nlov. 17 and '!ov. 22)
after transplanting. Kocide + Benlate were applied instead of Mlanzate + Benlate
on week 10 and 11 (Dec. 2 and Dec. 6).
c Manzate only on a 4 to 5 day schedule prior to week G after transplanting.
METHODS FOR COISTROLLINIG THE MOST COMMON
VEGETABLE VIRUSES Ii SOUTH FLORIDA
Thomas A. Zitter
Attached is a table which summarizes the 11 most common vegetable viruses that
occur in south Florida and the methods used to control them. This table is an ex-
cerpt from a forthcoming research report (EV-1979-7) with the above title. Although
aphids are responsible for the spread of 9 of the 11 diseases (exceptions are tobac-
co mosaic virus spread by contact and pseudo-curly top virus spread by treehoppers),
these control measures are not directed at aphids per se. Rather, these proven con-
trol measures developed over the past 10 years have drawn upon 1.) scientific in-
vestigations aimed at virus identification, establishment of vector-virus relation-
ships, and utilization of genetic resistance; 2.) extension programs for weed sani-
tation and seed indexing; and 3.) excellent qro'ier cooperation assuring initiation
of crop-free periods and seed certification. This cooperative effort has contributed
to successful disease control and a rewarding experience for researchers.
Table 1. Summary of the most common vegetable viruses in south Florida.
Susceptible Crop Virus Source and Location Transmission Control
including carrot and
of family Cucurbit-
summer types (yellow
str. neck and crook-
winter types (acorn,
virus strain 1
only members of
(WMV-2) with a
host range occurs
in central Florida.
Weed hosts include mock-
capillaceum and wild cherry
(Apium Ieptophyl um).
Both are annuals found in
southern and central Florida.
Celery itself is the main
source and will also infect
carrots and parsley.
Extensive host range,
although Commelina spp.
wanderingq jew or dayflower)
is most common reservoir
Weed hosts so important are
charantia) and creeping
cucumber (Melothria pendula)
plus the susceptible cucurbit
Because of limited
host range (infects
plants) a celery
break cycle. Oil
spray, though not yet
tested on celery,
should deter spread.
Commelina is low,
therefore clean ditch-
banks will remove border
effects and keep virus
out of crop, where
spread is greater.
Two major weed hosts
difficult to eliminate.
Twice weekly oil sprays
are approved for use
on squash and cucumber
assuring good protec-
tion. Clearance pend-
ing for other cucurbits.
Table 1, contd.
Susceptible Crop Virus Source and Location Transmission Control
and Endive (members)
of family ComDositae)
virus (CMV). Rarely
a problem, but
Capable of infect-
ing all three
endive and all
except Cos variety
with this form of
Commelina spp. Natural
infection noted in Everglades
and Ft. Pierce area during
past 10 years was clearly
associated with this weed.
Seed-borne in probably all
lettuce types but not in
escarole and endive. Weed
hosts not important; can
occur wherever lettuce is
Two major weed hosts through-
out the state are hairy
beggarticks (Bidens pilosa)
and Virginia pepperweed
(Lepidium virginicum), plus
other weeds. rot seed-
Infections are rare,
therefore rely on ditch-
bank sanitation to
control Commelina and
State controlled lettuce
seed indexing has all
but eliminated this
virus as a problem.
Soon to be released
although ability to
seed transmit still in
Good ditchbank sanita-
tion especially for
key weed hosts will
hold infections to a
bare minimum. New
lettuce varieties under
development also carry
resistance to this
Table 1, Contd.
Susceptible Crop Virus Source and Location Transmission Control
of family Solanaceae,
and applies to bell,
cubanelle, and other
No strains to
Potato virus Y
(PVY). No strains
to be noted.
Tobacco etch virus
(TEV). Two strains
are recognized and
for the common
isolate and TEV-S
for a severe
Commelina spp. Only 2
instances of natural infec-
tion over past 10 years
and only in Cos varieties.
Nightshade (Solanum spp.) and
groundcherry (Physalis sp.)
important source in lower east
coast area where virus is
commonly found. Also noted
in Immokalee area.
Harbored in solanaceous weeds
especially nightshade and
groundcherry. Common virus
infecting peppers grown
throughout the state and
especially east and west
coasts, areas in between
and south to Homestead.
Like PVY, TEV is common where
solanceous weeds occur. TEV-C
was the major east coast
virus during the 1977 to 1979
seasons. Also found in
western areas but not'at
Rarely seen, therefore,
normal -ditchbank sani-
tation will suffice.
Most pepper varieties
are susceptible with
the exception of 'Delray
Bell' and 'Greenleaf
Tabasco'. Use oil
sprays weekly during
periods of aphid flights
Newly released varieties
'Delray Bell' are resis-
tant to all isolates of
PVY'currently known in
Florida. Weekly oil
sprays work effectively
to reduce spread.
'Florida VR-2' resistant
to TEV-C but not TEV-S.
'Delray Bell' resistant
or tolerant to both. If
are grown and virus is
a problem, weekly oil
sprays during the season
Table 1, Contd.
Susceptible Crop Virus Source and Location Transmission Control
Commelina spp. Disease only
occurs along the east coast
but could be a problem in
along with weekly
Tomato (members of
and applies to all
fresh market types,
also speciality types.
strains exist in
the state, one of
which is seed-
borne in pepper.
Potato virus Y
Tobacco etch virus
only 1 strain
Solanaceous weeds, therefore
common disease in all pro-
duction areas. Abandoned
fields a source of
Solanaceous weeds. TEV-C
was the predominant east
coast tomato virus during
past two seasons. Aban-
doned tomato and pepper
fields are common sources.
Rarely a problem for
pepper, although most
varieties are suscep-
tible; 'Florida VR-2'
is resistant to common
strains; avoid hand
and machinery contact.
No resistant varieties,
therefore rely on weed
control and weekly oil
sprays in areas where
production is vulner-
No resistant varieties;
because this virus can
be so prevalent in
weeds and surrounding
crops like pepper,
growers need to con-
sider using weekly oil
sprays as a preventa-
Table 1, Contd.
Susceptible Crop Virus Source and Location Transmission Control
virus (TYV). Name
applied to yellow-
ing disease first
identified in 1978.
Primarily a disease
of tomato, but also
potato. Pepper is
a doubtful host.
virus (PCYV). Very
plant growth and
Nightshade is a very common
reservoir; also abandoned
Limited primarily to
solanaceous hosts, with
nightshade the major source;
groundcherry and Datura spp.
also susceptible. Can be
a serious disease in west
coast production areas.
Nightshade and groundcherry
are reservoirs, and probably
some plants outside
Solanaceae; can occur
throughout south Florida.
Commelina spp. in particular;
rarely occurring, so of no
Always a potentially
serious virus and
masked at times in
varieties; no complete
spread by contact.
and abandoned tomato
fields; weekly oil
sprays have shown
some success in reduc-
ing spread; no resis-
tant varieties known.
weed hosts before
regarded as a warm
weather insect, easily
controlled with insec-
Use normal ditchbank
sanitation; oil sprays
used for controlling
tomato viruses would
also be effective for
EFFECT OF BACTERIAL SPOT (Xanthomonas vesicatoria) O! PEPPER YIELDS
Bacterial spot of peppers incited by Xanthomonas vesicatoria, contributes a
great threat to successful production of bell peppers, especially in southern
Florida. No accurate estimates of losses incurred by this disease have been deter-
mined because of the unpredictability of this disease, which is dependent on the
weather conditions. This study was undertaken with the following objectives:
1. Determination of yield reduction due to bacterial spot.
2. Evaluation of various cultivars and plant introduction
(PI) accessions for their field tolerance to this dis-
Location: AREC, 'lorikami Farm
ilaterials and 'ethods:
29 bell pepper cultivars and 8 PI accessions (Table 1) were used in this study
The experiment was a split-plot design with 4 replications. Half the plots re-
ceived copper sprays (Kocide) once a week and the other half did not receive any
copper sprays. All plots were sprayed with oil to prevent the spread of virus
diseases. The other cultural operations were followed according to the standard
One month old seedlings were transplanted on November 3, 1970. Harvesting was
started on January 27, 1979, with one replication per week. !hole plants (tops)
were harvested and the following observations were made:
1. % defoliation (based on the number of leaves un to the
2. % fruitset (based on the first seven fruiting nodes).
Defoliation or the loss of leaf is one of the effects of bacterial spot infec-
tion. Defoliation is very important since the fruit size is directly dependent on
the leaf area within a given cultivar.
Early or the first few fruits are very important since they are larger and
ideal for fresh market. The effect of bacterial spot disease on the fruitset of
peppers have not been determined.
Results and Discussion:
The percent defoliation in plots receiving with and without Kocide are summa-
rized in Table 1. Percent defoliation was very high in both Kocide sprayed and
unsprayed plots. This was probably due to the occurrence of frequent rains during
the duration of the crop which might have washed off the sprayed materials from the
foliage. However, the plots receiving no Kocide had greater defoliation (Table 1).
The cultivars differed in their defoliation (Table 1). The popular cultivar
'Early Calwonder' appeared to be more tolerant to defoliation compared with the
virus resistant 'Florida VR-2' and 'Delray Bell' in the Kocide sprayed plots; how-
ever, in the unsprayed plots only 'Florida VR-2' showed greater defoliation compared
with 'Early Calwonder' or 'Delray Bell' (table 1). Although the actual defoliation
counts were not made on the PI accessions, visual observations indicated that some
of the accessions were superior in their leaf retention.
Fruitset from Kocide sprayed and unsprayed plots were not significantly dif-
ferent from each other (Table 1). This result again can be attributed to frequent
rains, which washed off the Kocide sprays from the plant foliage, thus leaving the
plants unprotected from the bacterial spot disease. This indicates that under fre-
quent rainy conditions bacterial spot infection may be severe and can result in
Cultivar differences in their capacity to set fruits were also noted. The
range of fruitset for various cultivars ranged from a low of 7.63% to a high of
49.93% in the Kocide sprayed plots whereas a low of 6.63% to a high of 65.1% was
noted in the unsprayed plots (Table 1). 'Early Calwonder' was not significantly
different from 'Florida VR-2' or 'Delray Bell' with regard to fruitset. The PI
163192 had better fruitset than all the others and may have a value in future
Summary and Conclusions:
This preliminary study indicates that under rainy wet weather conditions of
southern Florida, bacterial spot of peppers can result in heavy losses of the crop.
The commercially used copper sprays were ineffective under these conditions. Bac-
terial spot affects both defoliation and fruitset. Cultivar variations and per-
formance of PI accessions suggest that breeding peppers for bacterial spot resis-
tance may be an alternate and better approach to overcome this disease problem for
successful pepper production in south Florida.
Table 1. Average
values of % defoliation and % fruitset of
and unsprayed plots with Kocide
various cultivars in
% Defoliation % Fruitset
Varieties Source + Kocide Kocide + Kocide -Kocide
6c x 57 (F1)
Keyst. Res. Giant
nc x 4014
Calif. Under PS
Hyb. hybell (F1)
Yolo :Jonder A
Yolo Wonder L
P3 (F )
PI 163192 C. anni
PI 260434 C. cha
PI 322719 C. anni
PI 271322 C. ann
PI 281423 T. CiT
PI 260579 C. pen
PI 260571 C. peni
PI 260582 C. pen
Slouse & Groot
VEGETABLE RESEARCH OTI SANDY SOILS OF THE LO!ER EAST COAST, 1978
AREC, Iorikani Farm, Delray Reach
H. Y. Ozaki
Pepper Variety Trials (in cooperation with A. A. Cook and T. A. Zitter). In
a test without virus, Early Calwonder produced better quality pods than the pods
produced by Delray Bell. Early Calwonder produced 15 tons (33 tonnes) of U.S. fancy
plus U.S. 1 pods and 12 tons (27 tonnes) of fancy pods per acre (ha), which were
significantly higher than the 10 to 11 tons (22 to 25 tonnes) of fancy plus U.S. 1
pods and 6 to 10 tons (14 to 22 tonnes) of fancy pods produced by Delray Bell,
5C-X80, Starr, Florida VR-2, Pip, Hybelle Hybrid, OS, and Grande Rio 66. The last
group were not significantly different from each other for fancy plus U.S. 1 pod
yields. Delray Bell produced 13,000 (46,000) flat shaped pods per acre (ha); sia-
nificantly more than the 0 to 11,000 (27,000) flat pods produced by the other varie-
ties. Several other observations also indicated that Delray Bell produced flat pods
during the coldest winter in 10 years. Further observations were made on virus
tolerant lines superior to Delray Bell and Cuban El.
Pepper Insect Studies (in cooperation with U. G. renung). A pyrethroid, SD
43775 (Pydrin, 0.2 and 0.4 lb AIA; 0.22 and 0.45 kq Alha) applied at 3-5 day inter-
vals and O-S-dimethylphosphoramidothiate (Honitor 4, 1 lb AIA; 1.12 kq AIha) applied
at weekly intervals reduced the number of pepper weevils beaten from plants to 0.
The check plants had approximately 10,000 weevils per acre (25,090 per ha). The 0.5
lb AIA (0.56 kg) 0-S-d. treatment resulted in 4,000 (10,000) weevils.
In a second test with all treatments applied at 3-5 day intervals, the pyre-
throids, SO 43775 (0.2 and 4 lb AIA), and permethrin (Ambush, 0.1 and 0.2 lb AIA;
0.11 and 0.22 kg AIha) reduced the 16,000 (40,000) weevil count per acre (ha) of
check plots to 3,000 (7,000). The 9,000 (22,000) count from the 1 1b AIA (1.12 kg
AIha) treatment of 0-S-d. was not significantly different at the 5% level of statis-
tical significance from the check or from the other insecticide treatments.
Bean Variety Trials. NCX 8010, Tidal Have and Exp. 160 produced approximately
260 bushels (8,5 tonnes) of quality bush, snap bean pods per acre (ha) in the
Southern Cooperative Replicated Trial harvested in May. Other varieties tested were:
Raider, Plateau Provided, Exp. 139, H 197-5-1, BB1 GV 109, Early Gallatin, rP 72-115,
Cape, Strike, Triumph, Sprite, Rebel. Lines 6 BP-5, Exp. 169 and H285A-4-3 produced
approximately 140 bushels (5 tonnes) of quality pods in the observational trial.
Other entries were: Conquest, Exp. 121, Exp. 195, I.S.B. 9, ',!.H.P. 1. Valiant, GP
72-122 and Early qallatin.
Integrated Pest M[anagement for Bush, Snao Bean (in cooperation with H. G.
Genung, D. J. Pieczarka, and H. L. Rhoades). In the winter trial, eight weekly
sprays of mancozeb (ilanzate 200) plus wettable sulfur resulted in 140 bushels
(4.7 tonnes) of pods per acre (hectare). The.untreated check plots produced 170
bushels (5.8 t) with a market value of $7.66 per bushel ($228/t). The weekly sprays
reduced powdery mildew on the pods and increased the market value to $12.33 per
bushel ($357/t). Four mancozeb plus wettable sulfur sprays, with applications
started when the disease appeared (plus DOD-iencs plus ten diazinon sorays for leaf-
miners) resulted in 17. bushels (5.8 tonnes) of pods with the higher market value.
Four chlorothalonil (Bravo) sprays, with the first spray applied when disease ap-
peared, resulted in 140 bushels (A.7 t) of pods with higher dollar value. The check
leaves had 4 leafminer mines per leaf; diazinon sprayed leaves- 2; permethrin plus
oxyanyl leaves 0 mines.
In the spring harvested trial, seven mancozeb plus wettable sulfur sprays (plus
DD-lencs plus eight methonyl plus 10 dimethoate sprays) increased the yield above
the 9 bushels per acre (0.3 tonnes/ha) of unsprayed plots to 163 bushels (5." t).
The check pods had a zero value, but the sprayed pods were worth $5.50 per bushel
($164/t). Six mancozeb plus wettable sulfur sprays, first application sprayed when
rust appeared, (plus )D-'lencs plus five methomyl plus nine dimethoate treatments)
resulted in 123 bushels (4.3 t) of pods with a market value of $5.64 per bushel
($1G7/t). The six chlorothalonil sprays, first applied when disease appeared on
foliage increased the yields to 122 bushels (4.1 t) with a market value of %5.50
per bushel ($193/t). The mancozeb plus sulfur sprayed pods were lighter in color.
The check plot leaves had 94 rust pustules per leaf; mancozeb plus wettable sulfur
sprayed leaves -13 and 25, respectively; the chlorothalonil treated leaves averaged
36 pustules. The check leaves and dimethoate sorayev leaves averaged 9 leafminer
mines per leaf early in the season. Pernethrin leaves sprayed before oxyamyl treat-
ments started, had 2 mines. Later in 'ay the check averaged 4 mines per leaf; dime-
thoate sprayed leaves 13 and permethrin plus oxyanyl 10 mines per leaf. The check
leaves produced 11 leaf hooper nymphs per leaf but the sprays reduced the population
to zero. Average rootknot larvae counts per 100 cc of soil were: check 550;
DD-mencs fumigated 4; oxyamyl sprayed 700.