Title: Vegetarian
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00087399/00071
 Material Information
Title: Vegetarian
Series Title: Vegetarian
Physical Description: Serial
Creator: Horticultural Sciences Department, Institute of Food and Agricultural Sciences, University of Florida
Publisher: Horticultural Sciences Department, Institute of Food and Agricultural Sciences, University of Florida
Publication Date: March 1972
 Record Information
Bibliographic ID: UF00087399
Volume ID: VID00071
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.


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March 1, 1972

Prepared by Extension Vegetable Crops Specialists

George A. Marlowe, Jr.

James Montelaro

J. M. Stephens
Assistant Professor

J. R. Hicks
Assistant Professor

S. R. Kostewicz
Assistant Professor

R. K. Showalter

D. D. Gull
Associate Professor


FROM: James Montelaro, Vegetable Crops Specialist --r "




A. Seasonal Influence on Crop Maturity
B. Pinworm on Tomatoes
C. Late Blight on Tomatoes and Potatoes
D. Lettuce Mosaic Control
A. Controlled Ripening of Florida Tomatoes
B. Transpiration
A. Poultry Manure for Vegetable Crops
B. Florida Garden Poultry Manure Recommendations
C. Know Your Vegetables Chayote

NOTE: Anyone is free to use the information in this newsletter. Whenever
possible, please give credit to the authors.

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The VEGETARIAN Newsletter




A. Seasonal Influence on Crop Maturity

Florida vegetable growers have experienced two distinct situations
in the last two growing seasons. The 1970-71 season was one in which crops
were harvested 2 to 3 weeks later than when they were expected. On the
contrary, in the 1971-72 season, crops were harvested 2 to 3 weeks earlier
than had been planned. This wide variation emphasizes the influence the
season can exert on plant growth.

The general response of plants to unfavorable conditions is a slowing
in the rate of growth until more optimal conditions prevail. The resumption
of the rate of growth is slow and can be compared to the regaining of momentum
of a temporarily slowed flywheel. The length of this "lag period" is determined
by the severity and duration of the unfavorable conditions. It is this period
of slowed growth that results in differences between calendar and physiological
age of plants.

Temperature, all other factors being equal, exerts the most pronounced
effect on plant growth. Moderate changes in temperature can exert pronounced
changes in the growth rate. If we consider the temperature range of the last two
seasons, we find that 1970-71 was a cool, wet season. The 1971-72 season has been
a warm, moderate season. The cool weather of 70-71 resulted in slow growth of
the crops which extended the period from planting to the desired harvest stage.
Result: Harvest 2 to 3 weeks later than expected. The warm weather of the 71-72
season is allowing continuous rapid growth of the crops following planting.
Result: Harvest 2 to 3 weeks earlier than when expected. This variation is
seasonal temperatures is one of the difficulties in predicting when a crop will
be ready for harvest.

One method of measuring desired maturity, the linear heat unit system,
has been used with some success for many years by growers for certain crops
which change quite rapidly in quality after an optimal stage. The method
utilizes a system which keeps a summary of "heat units" during the season and
harvest takes place after a certain number is accumulated. The linear heat unit
system, however, is not readily adaptable to all crops.

Most crop production has relied on the calendar age method of determining
when to harvest. That is, crop X is supposed to reach desired maturity in Y
number of days. But as the results of the last two seasons have shown, this can
be misleading. There are varieties within any given crop that are classified
early, midseason, or late maturing. It is possible to find specific numbers of
days listed for a variety indicating when it will reach maturity. It often is
possible to find different numbers of days listed for the same variety but which
are from different sources. Why the variation?

It is important to know and remember that these values are not absolute.
They usually have been derived from averages of a number of seasons. One further
aspect to remember is that the average season in one area will be different from
another area. Thus, the performance of a variety may differ from its "advertised"
value due to a difference in season from where the seed was produced and evaluated
versus where the production area might be.


Another factor to consider is how the "average" was derived. That
is; is the value an average of the early and late seasons over the years, or
is it an average of only the early seasons over the years? This type of
information is relatively hard to obtain.

One of the important functions of a variety trial program is to evaluate
how varieties perform under conditions of a specific area. Thus, a "hot" variety
from another area may not be as desirable as "standard" varieties of the local

Desired maturity is directly influenced by the effects of the season on
growth and the reliance on absolute calendar age is misleading and incorrect.
The primary seasonal attribute influencing crop maturity is that of temperature
in terms of its regulation of the growth processes of plants.


B. Pinworm on Tomatoes

Tomato pinworm (Keiferia lycopersicella Busck) has been reported over the
years as a pest of greenhouse tomatoes in the north. It is a field pest of tomato
in southern California, Mexico and other Latin-American countries.

Recently, we have had several reports of severe tomato pinworm infestations
in greenhouses in north and central Florida. A home garden plot of tomatoes in
Tampa was reported destroyed by this insect. The gardener, a professional entomolo-
gist, made a positive identification of the pest. It was tomato pinworm.

The U. S. Department of Agriculture Farmers' Bulletin 2045 describes the
worm and the damage it does as follows:

"The tomato pinwornn is a small caterpillar about
inch long, with a slender yellow or ash-gray body bearing dark-
purple spots and with a light-brown or yellow head. It feeds
on the foliage of tomatoes and burrows into the fruit around
and under the stem, causing small pinholes."

Tomato pinworm has been observed in Florida tomato fields in limited
numbers. Growers should keep a lookout for it, as it is possible for it to become
a serious tomato pest in the future. Tomato pinworm has been reported to attack
potatoes, eggplant and certain weeds closely related to the tomato family.

In the meantime, greenhouse operators are advised by Mr. James Brogdon,
Extension Entomologist, to use the insecticide Sevin on a weekly basis when tomato
pinworm invades their greenhouse tomato crop.

C. Late Blight on Tomatoes and Potatoes

The February issue of the "Vegetarian Newsletter" carried an article on
late blight control after receiving reports of the seriousness of the disease this
season. A follow-up survey was made by the vegetable specialist and county agents
from Palm Beach and Dade Counties. The disease was found to be very serious on
tomatoes in Palm Beach County and serious on potatoes (not on tomatoes) in Dade County.


All involved in the problem are convinced more than ever that the
reason for failure in control of late blight is poor application techniques.
In Dade County, the Agricultural Extension Agent's Office teamed up with Plant
Pathologists from the Experiment Station in an attempt to deal with the pro-
blem. Late blight control was discussed in detail by Dr. Conover and Dr.
McMillan at a meeting held for tomato and potato growers in Homestead. The
points covered by Dr. Conover are summarized in a mimeo he prepared for the
meeting. It covers the subject from A to Z including such topics as speed,
droplet size, pressure, nozzle numbers, arrangement and size, gallonage,
frequency of application, etc. Every tomato and potato grower (as well as
producers of other vegetables) could benefit tremendously from this report.
Anyone wanting a copy can request one from this office.

D. Lettuce Mosaic Control

Lettuce mosaic is a virus disease which has been a serious problem at
certain times on all lettuce types in the major producing areas in Florida. It
also attacks escarole and endive. This disease is unique in that the main
source of innoculum is from seed and not maintained locally in wild hosts.
According to Dr. Tom Zitter, Experiment Station Virologist at Belle Glade, it
may be possible to reduce the incidence of lettuce mosaic significantly by:
(1) eliminating the source of innoculum which is introduced by the seed, and
(2) use of good cultural practices whereby infested crop residues are destroyed
shortly after harvest.

Growers from the Sanford-Zellwood and Belle Glade areas working with the
Institute of Food and Agricultural Sciences and Florida Department of Agriculture
representatives are now formulating plans to put the above ideas into practice.
Similar programs have proved to be 85 to 90% successful over a period of years
in California. Those interested in lettuce production will be kept informed of
developments in this program through the medium of this newsletter or they may
write this office directly.

For the present, lettuce growers are advised to buy the best quality
lettuce seed available. Seed that has been tested and found essentially free of
mosaic (0 in 30,000 seeds) are available for some varieties of lettuce. Even
though it is more costly, we consider it to be a very worthwhile investment. In
addition, lettuce growers should destroy all lettuce crop residues as soon after
harvest as possible.




A. Controlled Ripening of Florida Tomatoes

During the last three years, there has been a transition from shipping
green tomatoes to northern ripening rooms to grower-level ripening in
specially constructed ethylene treatment rooms.

The use of volatiles to promote ripening of certain fruits dates from
the ancient Chinese. As early as 1925, it was demonstrated that ethylene,
at concentrations of as low as 250 ppm, caused acceleration of tomato ripening.

Ethylene is a naturally occurring gas. It is non-poisonous but flammable
and explosive in concentrations from 30,000 to 280,000 ppm. However, at the
concentrations which are effective in fruit ripening, ethylene may be handled
with complete safety if simple precautions are taken while the gas is being
admitted to the treatment chambers. These precautions include elimination of
open flames, no smoking, and exclusion of equipment capable of producing sparks.

The tomato fruit is a living product, and a minute quantity of ethylene
is produced during growth and maturation. At the advanced mature-green stage,
the production of ethylene is greatly accelerated and, therefore, the tomato will
ripen naturally. The addition of external ethylene at this stage of development
will not affect the rate of ripening. Ethylene applied to less mature tomato
fruits (those which have not developed sufficient ethylene to initiate ripening)
will cause an immediate initiation of color development and other ripening processes.
Within any given box of green tomatoes, there will be fruit of varying physio-
logical age and, therefore, variation in the rate of ripening. Application of
ethylene will initiate ripening of those less mature fruit and, therefore, result
in a pack of more uniform coloration.

1. Recommendation for Treatment

Only tomatoes that are fully mature-green as commercially feasible
should be placed in a gas-tight room where a temperature of 68-720 F. can be
maintained. The relative humidity within the room should be maintained at about
90%. Ethylene should be injected into the room at a concentration of 1000-2000
ppm and circulated with internal fans. Ethylene will soon come to equilibrium
with the air, and because of its diffusibility will permeate inside of the
stacked boxes of tomatoes. The duration of gassing should be from 24 to 72 hours
depending upon response of the tomatoes. Weather conditions during growth,
cultural practices, maturity, and temperature all affect the ripening response;
therefore, all lots of tomatoes will not react the same.

During the gassing operation, the respiring fruits are consuming
oxygen and evolving carbon dioxide. In these gas tight rooms, the carbon dioxide
level can increase to 3% in less than 12 hours. High levels of carbon dioxide
have an inhibitory effect upon ethylene-induced ripening. Laboratory tests are
being conducted to determine carbon dioxide level which interferes with tomato
ripening. Accumulation of carbon dioxide in ripening rooms can be reduced by
operation of a carbon dioxide "scrubber." Such scrubbers are routinely used in



controlled-atmosphere storage of apples. However, due to excessive amounts
of carbon dioxide being evolved by the tomatoes, a "flow-through" or "trickle"
system would be far more economical. It is a common commercial practice to
gas tomatoes for 12-24 hours, then open the rooms and inspect the fruit;
tomatoes may be regassed for 24-hour intervals once or twice more depending
upon coloration of the fruit. At the recommended ethylene concentration and
use of a scrubber, rooms could be entered for fruit inspection without having
to regass afterward.

In commercial gassing rooms, ethylene is most easily metered on a
weight basis. A room having a volume of 1000 cu. ft. would require 1.25 ounces
of ethylene to obtain the desired 1000 ppm concentration.

2. Precautions

A high quality tomato must possess more than good external appear-
ance. Suitable acidity, sugars, and the flavor volatile content are character-
istics that account for repeat sales by the consumer. Immature tomatoes do not
possess these desirable characteristics, nor will they develop during the
ripening process. Gassing and sale of underdeveloped fruits will only result
in consumer dissatisfaction and enhancement of purchasing of more desirable
tomatoes from competing areas or utilization of substitute products.

If additional information is desired, contact D. D. Gull, Vegetable
Crops Department, University of Florida, Gainesville, Florida, 32601.


B. Transpiration

Transpiration is water loss (or evaporation) from living tissue. This
process is directly and indirectly responsible for a large portion of the
difference between the amount of produce which is originally sold by the packer
and the amount ultimately sold by the retailer. The direct loss is due to a
reduction in quality. A wilted commodity (example, lettuce, cucumbers, carrots,
etc.) simply does not have the appearance or texture (crispness) that is associated
with high quality. This loss of quality often results in reduced prices, if the
product can be sold at all. The indirect loss is much more discreet. Most fresh
produce can lose 1 or 2% (some commodities can lose much more) of its total weight
without noticeable effects, but there is a difference in the weight sold by the
packer and the amount sold by the retailer.

Transpiration, like respiration, cannot be completely eliminated, but it
can be controlled to some degree. Most fruits and vegetables contain between
80 to 90% water and the relative humidity in the air space within the commodity
is maintained at or above 99%. Since water vapor, like other gases, tends to
diffuse, or move from areas of high concentrations to areas of lower concentra-
tions, there will be some water loss as long as the air surrounding the produce
has a relative humidity of less than 99%. The recommended relative humidity for
most fruits and vegetables is between 85 and 95%. Below 85%, transpiration is
usually rapid enough to become a problem and above 95%, it is almost impossible
to control the growth of molds and other organisms in the storage room. In
addition, a tremendous amount of refrigeration coil surface is necessary to main-
tain a relative humidity above 95%. When air is cooled, the water holding capacity

m -


of that air is reduced. This means that in a produce storage room operating
at 330 F., the air returning to the refrigeration coils is probably a little
obove 330 and is saturated with water picked up from the produce. If the coil
temperature of the refrigeration unit is 280, that portion of the air (not all)
which comes directly in contact with the coils will be cooled to 280 with the
corresponding loss of water. This air will return to the room and remove heat
from the 330 air, cooling it to about 320 and also remove moisture from the
warmer air. This cycle repeats over and over with the moisture being picked
up from the produce and deposited on the refrigeration coils. The closer the
coil temperature is to the room temperature, the less drying effect there will
be. However, the closer the coil temperature is to the room temperature, the
greater the proportion of air which must come into direct contact with the
coils and hence, the need for larger coil area.

In relation to refrigeration and yet from a different angle, when produce
is stored in a refrigerated room, the room temperature also has a pronounced
effect on transpiration. Fresh produce will lose moisture twice as fast at 500
as at 320 and twice as fast at 700 as at 500 at a relative humidity of 90%.
Again, this is due to the greater moisture holding capacity of air at higher

The rate of air movement has a tremendous influence on desiccation of
fresh produce. As mentioned earlier, water vapor moves from areas of high con-
centration (in produce) to areas of lower concentration (air). However, gradients
of varying moisture concentration will develop if the air flow is not too great.
For example, the relative humidity in the produce may be above 99%, while at the
surface of the produce it may be 99%. A little farther away, it may be 98% and so
on until eventually, at some distance it will be 90% or at whatever the room is
being maintained. However, if the air movement is rapid and flowing directly over
the produce, the relative humidity will still be above 99% within the produce, but
at the surface it can be 90% or lower depending on the relative humidity of the

Containers also play a role in transpiration of fresh produce. They can act
in the beneficial manner described above of restricting air movement. They may also
act in a detrimental manner by absorbing water from the produce. This problem can
be reduced by using a container or liner that does not readily absorb moisture.

Waxing is another method of restricting air movement and reducing moisture lo
With waxing, as well as other types of restricting air movement, care must be taken
to avoid creating a static system where there is no ventilation or air exchange.

The type of vegetable also determines how great a problem transpiration will
be. Usually the greater surface area commodities have the greatest transpiration
rates. Lettuce and other leaf crops are prime examples of high surface area
commodities. In some commodities, such as radishes, carrots, etc., the tops, which
readily lose water, are removed to prevent depleting water from the edible portion.
Sweet corn is another example of the unedible portion being detrimental to the
edible portion. With the shank intact, the outer husks on an ear of corn will
remain green and turgid while another ear, with the shank trimmed, will show loss
of color and wilting of the outer husks. With the shank intact, the husk has access
to the moisture in the kernels. With the shank trimmed, the husk is on its own
and consequently kernel denting is much slower.

(Hicks and Showalter)




A. Poultry Manure for Vegetable Crops

Wherever still available, poultry manure should be considered as a
fertilizer and soil conditioner for vegetable gardens.

Studies were conducted on sandy soils at Auburn University in 1962-63
to determine the effects of using poultry manure alone and in combination
with inorganic fertilizer. In 1968, the researchers, L. M. Ware and W. A.
Johnson, published Bulletin 386, "Poultry Manure for Vegetable Crops."

Here in brief summary are a few findings of the Auburn study:

(1) Rates of 3, 6, and 9 tons of poultry manure per acre gave equal
increases in yields of the first crop of tomatoes. Thus, for a single crop on
sandy soil, three tons of dried broiler manure per acre would give satisfactory

(2) Rates of 3 and 6 tons per acre were adequate for only the spring
crop; however, the 9-ton rate gave suitable yields over a two-year period (a
residual effect).

(3) Best method of applying was broadcast rather than in the row. In
all cases, manure was applied 3 weeks before planting; fertilizer was applied
as 1,000 pounds of 6-6-6 at planting and repeated 4 weeks later.

(4) Manure with commercial fertilizer gave higher yields than fertilizer
without manure.

(5) Treatments receiving both manure and commercial fertilizer did not
give higher yields than those receiving manure alone either of the first two
years. However, for the residual period of three years, the fertilizer plus
manure gave higher yields than the manure alone.

(6) Repeated applications of manure did not appreciably affect soil
acidity. Repeated applications of commercial fertilizer increased soil acidity

B. Florida Garden Poultry Manure Recommendations

Based on the above study and other factors, the following suggestions
are made for the use of poultry manure in Florida home gardens. Consideration
has been given to the variability of manure due to type, age, and condition of
bird; to the kind of feed used; to the age of degree of rotting of the manure;
to the moisture content of the manure; and to the kind and amount of litter or
bedding mixed in the manure.


Suggested Application Broadcast evenly over the entire soil surface
and spade or roto-till into the soil 15 pounds per 100 square feet (about 3
tons per acre) supplemented with 1 to 2 pounds of ground rock phosphate, raw
bone meal, or superphosphate. After spreading the manure, broadcast 2 to 3 pounds
of 6-6-6 or 6-8-8 (or similar analysis fertilizer) per 100 square feet.

At planting time, band apply 2 to 3 pounds of 6-6-6 or 6-8-8 (or similar
analysis fertilizer) per 100 square feet of row. Thus, on a 1-foot wide bed
such as for radishes, you would distribute the 2 pounds of fertilizer in a band
beside 100 feet of row; whereas, with a 3-feet wide bed you would band the
2 pounds along 30 feet of the row. Sidedressings should be made (if needed) with
the 6-6-6 fertilizer.

C. Know Your Vegetables Chayote

The chayote has been grown in Florida for many years to a limited extent.
While native to Guatemala, it is popular throughout tropical regions, where it
is known by several names including "vegetable pear", mirliton", and "mango squash".

It is a tender, perennial-rooted cucurbit, with climbing vine and leaves
resembling those of its cousin, the cucumber. The light green, pear-shaped fruit,
which contains a single, flat edible seed, may weigh as much as two or three
pounds. While fruits may be slightly grooved and prickly, those in Florida are
usually smooth. A root-like, starchy tuber (also edible) forms under the crown.
In most cases, it is the fruit for which the plant is grown.

Main varieties are Florida Green, Monticello White and the imports.

Supports Some type of trellis or support for the climbing vines is
required. Most trellises in Florida have been constructed about head high to
facilitate walking beneath the vines for harvesting and other operations. Other
types of support, such as a single-row, angle-staked trellis might work as well.

Seeds The whole fruit is planted as a seed. Each fruit has a single
large, close-fitting seed which sprouts as soon as the fruit reaches maturity
unless placed in cool storage. Fruits stored at 500 to 550 F. should remain
in good condition for planting for as much as six to eight weeks.

Planting The entire fruits are planted one-per-hill in hills spaced
12 feet apart in rows spaced 12 feet apart. The fruit is placed on its side
with the smaller, stem-end sloping upward. While the stem-end is often left
slightly exposed, in colder areas of Florida growers have found that the fruit
should be completely covered with soil to protect the bud from cold damage.

Fertilizing Well rotted animal manures or composted materials are
beneficial. On most sandy soils, about 3 pounds of 6-8-8 fertilizer per plant
should be applied in three applications 1 pound at planting time, 1 pound in
the middle of the summer, and 1 pound when fruits are small. Fertilizing at
more frequent intervals might be necessary when conditions warrant.



Use The chayote may be served in many ways creamed, buttered,
fried, stuffed, baked, frittered, boiled, mashed, pickled, in salads, or
in pies. Commercially, the biggest market appears to be for pickling.

Storage Fruits may be stored in edible condition for several weeks
if wrapped in newspaper and kept cool (500-550 F.). At room temperature, the
fruit will shrivel and sprout. The longer fruits are stored, the poorer the
quality becomes.

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