June 9, 1975
Prepared by Extension Vegetable Crops Specialists
J. F. Kelly
S. R. Kostewicz
J. R. Hicks
J. M. Stephens
R. K. Showalter
TO: COUNTY EXTENSION DIRECTORS AND AGENTS (VEGETABLES AND HORTICULTURE)
AND OTHERS INTERESTED IN VEGETABLE CROPS IN FLORIDA
FROM: Stephen R. Kostewicz, Extension Vegetable Specialist
VEGETARIAN NEWSLETTER 75-6
IN THIS ISSUE:
I. NOTES OF INTEREST
A. Call for Papers -- 1975 FSHS Meeting
II. COMMERCIAL VEGETABLE PRODUCTION
A. Reflections and Observations on Existing Greenhouse
Tomato Production in Florida
B. Water Quality--Problems and Solutions in Vegetable
C. Two "Soil Activators" Extensively Tested with Negative
III. VEGETABLE GARDENING
Timely Gardening Topics
Know Your Vegetables Citron
NOTE: Anyone is free to use the information in this newsletter.
possible, please give credit to the authors.
COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS. STATE OF FLORIDA, IFAS, UNIVERSITY
OF FLORIDA. U, 8, DEPARTMtLNT OF AGRICULTURE. AND BOARDS OF COUNTY COMMISSIONERS, COOPL RATIN(
FLORIDA COOPERATIVE EXTENSION SERVICE
UNIVERSITY OF FLORIDA
INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES
VEGETABLE CROPS DEPARTMENT
Tli EGETARI AN! Newsletter
f p I f l,~
THE VEGETARIAN NEWSLETTER
I. NOTES OF INTEREST
A. Call for Papers -- 1975 FSHS Meeting
Any member wishing to present a paper in the VEGETABLE SECTION at the
November 4-7, 1975, meeting of the Florida State Horticultural Society should send
his title and two copies of an abstract of 100 to 150 words to me at the following
address not later than July 1, 1975: University of Florida, IFAS, Vegetable Crops
Department, 3026 McCarty Hall, Gainesville, Florida, 32611. The senior author of
the paper must be a member of the Society. Other authors are encouraged to be
The Society prefers papers that describe completed applied research pertaining
to horticultural plants and products, or new developments and practices that have
been put in use by growers, processors, allied industries, or other horticultural
interests in Florida. Papers written by growers and processors are definitely desired.
The Society does not prefer purely basic research papers, papers of a pro-
motional nature, progress reports, or papers in which the growing, harvestin.,
handling, marketing and processing of Florida horticultural plants is only remotely
I will notify senior authors concerning the acceptance, handling and schedul-
ing of their papers. If there are any questions, my phone number is 904-392-1794.
II. COMMERCIAL VEGETABLE PRODUCTION
A. Reflections and Observations on Existing Greenhouse Tomato Production in Florida
County extension personnel in north and west Florida are acutely aware of
the recent surge of interest or popularity of greenhouses for tomato production.
Hardly a day passes without this office learning of a new "house", or answering
questions from interested parties seeking information on this type of production.
Our position on the feasibility of this type of production remains unchanged
in that we do not unqualifyingly encourage people to undertake this type of culture.
We continue to point out the many difficulties and urge very close scrutiny relative
to marketing outlet and cost of production for tomatoes grown in this manner. In
other words, we are not overly optimistic yet, we try to be as objective as possible.
It is unfortunate that most of the people we find operating these houses have had
very little prior exposure to agriculture, let alone the intensive type of pro-
duction required for vegetables, and the even more intensive culture of greenhouse
tomatoes. Most are lured into purchasing these houses by the claims of high returns
reported by most outfits selling these units. These claims are theoretically attain-
able, but most of the figures have been interpolated fron production areas outside
of Florida and the southeast. As yet, we have been unable to find a house in Florida
attaining the high yields claimed.
This office has and will continue to offer assistance with production pro-
blems for agents with greenhouse operations in their counties. However, the problems;
most frequently encountered by this author have been with fertilizer practices and
THE VEGETARIAN NE NSLETTER
In the area of fertilizer elements, nitrogen, potassium, magnesium and
calcium have been the most frequent problem areas. Usually on questioning the pro-
ducer as to his fertilizer practices, one finds that he knows very little about the
details. The response usually is, "I use 1 teaspoon of Brand X fertilizer per
gallon every time I water". The analysis is not known by the producer, but this is
what the instructions with the house said to use.
Specifically, this author has observed the following:
(1) Excessive nitrogen fertilization resulting in;
(a) poor fruit set,
(b) a dense canopy offering poor air circulation resulting
in disease problems.
(2) Potassium deficiency accompanied by;
(a) poor growth, typical foliar deficiency symptoms,
(b) plant responses to KC1 applications.
(3) Calcium or water stress resulting in;
(a) blossom-end rot,
(b) recovery in young fruit following application of calcium.
(4) Magnesium deficiency accompanied by;
(a) severely yellowed leaves showing the dark veins typical
of the symptoms.
(5) Soluble salt injury
(a) resulting from too much fertilizer too frequently,
(b) leading to typical burning of leaves beginning at base
of plant and progressing upward.
The usual response of the producer without any knowledgeable help is to start
switching brands of fertilizer until his crop "recovers" or is lost. Diseases have
been a serious problem in most of these houses, and one might say, "If the fertilizer
program doesn't get them, the diseases usually will". Leaf mold and botrytis have
been the most damaging. On a good spray program with proper ventilation to keep
humidity below 85-P9%, these diseases can be held in check. The problems with these
diseases usually can be traced to one of the following in most houses this author
(1) Spray program lacking or erratic.
(2) Poor spray coverage.
(3) Excessive humidity usually caused by:
(a) poor air movement in the house,
(b) excessive foliage (high N or poor pruning) which results in
poor air circulation into the plant canopy.
As most know, these problems are severe and reduce yield potential drastically.
Other problems, cultural and managerial in nature, usually can be found in most
houses and indeed few to our knowledge are making money when one considers all the
facets of this intensive culture. We remain willing to cooperate with agents on
houses having problems in their county in the best way we can. This author plans
to contact counties in the future in an attempt to pinpoint and have a clearer
picture as to the status of these operations in the state. Your cooperation in
this regard will be much appreciated.
THE VEGETARIAN NEWSLETTER
B. Water Ouality--Problems and Solutions in Vegetable Production
This is the second in a series of articles dealing with problems encountered
by producers of vegetables in Florida using poor quality irrigation water. This
article discusses changes in production practices which might be used to cope with
these problems. The reader is referred to our introductory article of last month
for a discussion of water quality--definition, measurements, classification, etc.
Irrigation water to be used for vegetable production should be analyzed for
total soluble salt (TSS). A water-quality analysis permits growers to make plans
for modification of production practices, if necessary, to avoid or to reduce the
injurous effect of high soluble salts. Following are some of the production
practices which can be modified to reduce the effects of poor quality irrigation
(1) Select "salt-tolerant" crops
Crops vary in their susceptibility to salt injury. Strawberries, beans,
celery and radish are highly susceptible (very low tolerance) to injury from high
TSS. On the other hand, tomato, broccoli, cabbage and cauliflower are quite
tolerant as shown in Table I. This does not mean that those crops in the "tolerant"
groups cannot be injured by high salts. It only means that they are not injured
as readily as the others by high concentrations of salts. For example, cucumber
and cabbage growing side by side in a field in Central Florida last spring and
irrigated from the same well responded differently to high TSS. Cucumber was
severely injured by high salts, but the cabbage crop appeared to be normal.
Table I. Relative Tolerance of Vegetable
Crops to Salt Injury
Relative Tolerance Crops
Bean (Bush & Pole)
Very low Celery
Medim Sweet Potatoes
Very high Kale
THE VEGETARIAN NEWSLETTER
(2) Modify bed shape
Soluble salts move in soil water. During periods of evaporation,
they accumulate at the center or the highest point in the bed. Flat-top beds are
recommended as a means of reducing salt injury to single-row crops. Two-row crops
might best be planted on a crowned bed.
(3) Use containerized transplants to start crops, where possible
Seedlings of all crop species generally are susceptible to salt injury.
As seedlings grow, they become less apt to be injured by high salts. Containerized
transplants, where applicable, can be used instead of direct seeding to reduce
seedling injury from salts.
(4) Modify irrigation methods
Many vegetables are grown under seepage or sub-surface irrigation. As
soil moisture evaporates, salts accumulate at or near the soil surface proportionate
to the amount of TSS in the water and the length of the evaporation period. High
salt concentration near the soil surface can be damaging to seedlings. Moved by
a light rain to the root zone of a growing crop, the same salts can injure the more
mature crops, as well.
To counteract this problem, it is suggested that growers switch to over-
head sprinkler irrigation when using low-quality water. By continually moving the
salts down, surface salt accumulation can be reduced significantly. NOTE: Recent
developments in drip irrigation looks promising as a method of not only conserving
water, but lessening salt problems.
(5) Irrigate heavily to wash salts below root zone
Using overhead sprinkler systems as suggested above, it would be wise
to irrigate with sufficient quantity of water to move the salts below the root zone
each time. By doing this, soluble salts accumulating in the effective root zone
can be maintained at lower levels than otherwise.
(6) Modify fertilizer and fertilization practices
There are a number of practices in fertilization which can be modified
to reduce TSS. It should be remembered that fertilizers contribute to TSS soluble
salts as does irrigation water. Following are suggestions for managing a vegetable
fertilizer program where soluble salts may be a problem.
(a) Use the low-salt index materials in all fertilizers.
(b) Apply the fertilizer more frequently and in smaller amounts.
(c) Broadcast and mix into the soil part or all of the basic or initial
application of fertilizer used before, at or following plantings.
It is possible for growers to modify their production practices to produce
most crops satisfactorily with their present supplies of irrigation water provided
they are not overly high in soluble salts. However, the simplest solution to poor-
quality water problems would be to find a better source of water. This subject
will be covered in a succeeding article.
(Montelaro and Locascio)
THE VFTFT4r IAN NEWSLETTER
C. Two "Soil Activators" Extensively Tested With Negative Results
A number of materials, under various trade names, are being sold to vegetable
growers as "soil activators." Purportedly, the soil activators offer a myriad of
benefits ranging from disease control to biological conditioning of the soil. Are
they really worthwhile? No, says a report published recently for at least two
soil activators tested extensively. The study is summarized in Southern Cooperative
Series Bulletin 189 entitled "Effect of Two Soil Activators and Activities of Soil
Microorganisms in the Southern United States."
The study was conducted over a three year period by twenty soil scientists
from eight state experiment stations and the USDA. It covered field and laboratory
studies with a number of crops under a wide variety of climatic and soil conditions.
The results can be relied upon to be accurate. The results obtained with the two
soil activators tested (Medina and Supernate) are as follows:
"1. Based on laboratory analyses, Medina and Supernate
contain plant nutrients that are already common to soils.
Amounts of these elements, that would be added to soil, based
on manufacturer's recommendations, would be low in relation to
crop nutrient requirements.
2. Application of these products at recommended rates did
not alter the number or activity of microorganisms that were
naturally present in soil. The microorganism population in the
products was considered to be too low for the products to be
regarded as soil or plant inoculants.
3. The severity of cotton root rot was not reduced in
greenhouse tests or in well-designed field trials where plots
were of reasonable size for plant or yield evaluation.
4. Yields of grain sorghum, cotton, oats or bermuda-
grass forage, soybeans, rice, peanuts, or tomatoes were not
significantly increased with recommended application of Medina
or Supernate. Products were evaluated both with and without
conventional fertilizers, on a wide variety of soils, and in
irrigated and dryland fields. Where yields of succeeding crops
were obtained, there was no indication of a delayed benefit."
It is not the intent of this article to condemn all new "products and services
as some may have potential for use in crop production. However, the results should
convince vegetable growers to look into new products and services very carefully
before spending money on them.
III. VEGETABLE CARDENIN:
A. Timely Gardening Topics
These questions and answers are suggested for agents' use in developing
periodic (weekly) radio or newspaper briefs. They are based on letters of inquiry
from Florida gardeners.
THE VEGETARIAN 'rV LETTER
(1) Timely Topic for week of June 15-21.
Recently, I have seen advertised garden watering kits called trickle irriga-
tion. What are these and are they of value?
Trickle or drip irrigation is a relatively new method of irrigation, as far
as gardens are concerned. The technique involves supplying plants with constant
moisture at a low delivery rate and at very low operating pressures through
specially designed tubing. Several systems are available to home gardeners, although
most have to be ordered from distant supply companies. All systems need a source
of water such as the house spigot, a distribution system to each row, pressure
regulator, a filter, and most important, the drip lines. Most common drip lines
now available are Chapin Twin-wall, Drip-Eze Biwall and DuPont Viaflo.
The advantages are many, some of which are: water conservation, energy
savings, ease of wetting on deep or sloping sands, reduction of weed growth in row
middles, ease of water application, fertilization through water under plastic,
avoidance of wetting and rinsing leaves, and minimum disturbance of soil structure.
(2) Timely Topic for week of June 22-28.
We are interested in starting a community garden project. What are some of
The most important requirement for any successful community garden project
is a "leader"--someone with enthusiasm plus a gift for organizing.
Next, you will need land, some sources of which are community-minded com-
panies, local planning authorities, church groups and public spirited private
The best location is within easy reach of the majority of participants, and
with access to a water supply. Secure a location that is not temporary.
Hire someone to plow the entire area, then keep in mind the need for toilet
facilities, lockable tool shed and a fence to prevent vandalism and thievery. Divide
the land into equal plots, allocating one plot to each gardener or family group.
Gardening the entire area like one big "commune" doesn't always work. Each person
with his own area to plant and care for is best. Keen plots small so gardens are
(3) Timely Topic for week of June 29-July 5.
I often see potato sprouts or buds for sale as seedpieces. Will these sprout
and produce a crop?
THE VEGETARIAN NEWSLETTER
Such a sprout is usually a bit of tuber about the size of the thumbnail
which contains a single eye (a bud). Yes, seednieces will sprout and produce a
plant, but research has shown that best yields are obtained from larger seedpieces
which average at least 2 ounces in size and, of course, which contain at least one
(4) Timely Topic for week of July 6-July 12.
What are some good cover crops for my Florida home garden?
A good cover crop should be leguminous; that is, have the ability to convert
atmospheric nitrogen to organic nitrogen. Actually, one of the best choices for the
average home gardener would be Southern peas. Their use as a summer cover crop can
provide two-fold benefits--soil improvement and food production; although most
varieties produce more vines than pea pods in the summer. Other good choices, depend-
ing on local adaptations, are crotalaria, hairy indigo, sesbania and lupine. Sesbania
requires a wet low land soil for good growth. Keep in mind that seeds of Crotalaria
spectabilis are toxic to livestock.
Besides cover cropping, gardeners have several other good ways to improve
garden soil such as incorporating compost and animal manures.
B. Know Your Vegetables Citron
Citron, Citrullus lanatus var. citroides, is also known as stock melon and
preserving melon. It shoiulTnot be confused with the citron of the citrus fruit
family (Citrus medical) whose peel is candied and frequently used in fruit cakes.
The citron melon is a plant of the same species as watermelon, but the fruit is
inedible in the raw state. These fruits resemble small watermelons, being round to
oval, up to 6 inches long, light green with darker green stripes, and smooth-
surfaced. The flesh is white and so tough that the fruits can be bounced on the
floor with only a small chance of bursting. The seeds are not marbled as often as
those of watermelons. Each of the low, "running" plants, like the watermelon, has
both male and female flowers, requiring bees for pollination. Due to the close
relationship to watermelon, cross-pollination between the two occurs often. Gardeners
should not be concerned with the results of such crossing, unless seeds of the
melons are saved for planting.
Volunteer citron plants are commonly found scattered around old fields and
road-sides throughout Florida. They are not often cultivated, but where desired,
they should be grown in a manner similar to watermelons and cantaloupes. The flesh
and rind are sometimes used for making preserves and pickles. Other reports indicate
occasional use as hogfeed.