INSTITUTE OF FOOD AND FLORIDA
AGRICULTURAL SCIENCES COOPERATIVE
UNIVERSITY OF FLORIDA EXTENSION SERVICE
I I II II I I
.June 17, 1981
Prepared by Extension Vegetable Crops Specialists
C .A. Ma r lo e
r i f e Ks, o r
Assist n t
Assistant Pro F -: r
4;e i a t e Professor
(: COUNTY EXI'ErN3LON DIRECTORS AND AGENTS (VEGETABLE AND
I T f C LT U R E )
:RO'M: M. Stall, Extension Vegetable Specialist )' v.fi
Vegetable Crops Department
1255 HS/PP Building
University of Florida
Cainesville, FL 32611
VF~ETARIAN NEWSLETTER 81-b
[N THIS ISSUE:
T. \NTES OF INTERI.ST
A. Coming Events
B. New vubl cations
C. Susni Gray Leaving Vegetiable Crops Department
tIC. COMMERCIAL VEGETABLE PRODUCTION
A. 1981 Field Blossom-end Rot Problems
H. Using Rates of Maturity as a Management Tool
I [t. HARVESTING AND HANDLING
A. Chlorine Management
IV. HOME VEGETABLE GARDENING
A. When to Pick the Vegetable Garden
B. Know Your Minor Vegetables Rakkyo
The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity Affirmative Action Employer authorized to provide research.
educational information and other services only to individuals and institutions that function without regard to race, color, sex, or national origin.
COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS, STATE OF FLORIDA, IFAS, UNIVERSITY OF
FLORIDA, U. S. DEPARTMENT OF AGRICULTURE, AND BOARDS OF COUNTY COMMISSIONERS COOPERATING
I. NOTES OF INTEREST
A. Coming Events
Be sure and mark these events on your calendar.
Detailed programs will be included in subsequent issues.
Tomato Institute will be held Thursday, September 10,
1981 in Naples.
Tomato Packinghouse Conference will be held Friday
morning, September, 11, 1981 at Marco Island.
The State 4-H Congress is rapidly approaching. It will
be held July 27-30, 1981, with State Events Day being
Tuesday, July 28. Two horticultural events will take place
at that time: The Horticultural Demonstration Contest and
The Horticultural Identification and Judging Contest. Both
events will be held at the Horticultural Science/Plant
Nine district champion demonstrations are scheduled For
the demonstration contest, and each county may enter a t ean
in the Identification and Judging event. I encourage all of
you to partLcipate. Please contact me if you need further
information. Though I will no longer be here after June 30,
I will be coordinating both events.
June 30, 1981 will be my last day of employment in the
Vegetable Crops Department. I want to express my
appreciation and thanks to each of you who have made the
past 7 years so fulfilling and enjoyable for me. I regret
very much the fact that I must leave.
The cooperation I have received in the hurticul ttiral
youth and Master Gardener programs has been excellent. I
feel we have accomplished much in both areas and wiqh for
this progress to continue.
There are so many people I would like to thank for the
support they have given to my work. Without that support
and cooperation, our success would not have been possible.
I ask all of you to continue your support of these program
Thanks again to each of you. I sincerely appreciate all
of your efforts on my behalf. Best wishes.
II. COMMERCIAL VEGETABLE PRODUCTION
A. 1981 Field Blossom-end Rot Problems
Blossom-end rot of tomato, pepper and watermelon first
becomes apparent as a water-soaked lesion or series of
lesions on the blossom-end of the fruit. This can happen at
anytime during fruit enlargement and maturation. The tissue
breakdown usually develops rapidly, eventually becoming
sunken, dark and leathery.
Blossom-end rot is a calcium deficiency disorder. This
year, however, we are seeing the disorder in soils with
optimum to high available calcium.
The reason for this is several fold.
1. Ca Uptake
Interactions with other ions can strongly influence
uptake of Ca by the plant. Non-specific competition
(cation antagonism) notably by K, Mg, and Na and NH4
can substantially depress Ca uptake. Of these
cations, ammonium tends to decrease calcium uptake
the most, sodium the least.
2. Ca Translocation and Distribution
A low Ca content in the fruit, causing blossom-end
rot may not be a result of insufficient Ca but
rather a problem of distribution in the plant.
Calcium transport in the plant is relatively slow and
primarily in water in the xylem. Transpiration then
becomes a prime mover of xylem water and Ca.
Shortage of water or an irregular water supply
results in reduced Ca translocation, especially into
fruit. Fruit have low transpiration rates but a
high Ca demand.
When water is supplied to drought stressed plants,
water in the plant moves primarily to leaf tissue
and not to fruit and results in Ca deficiency.
In contrast, withholding water has little effect on
Mg and almost no effect on K influx into the fruit.
This tends to increase the Mg+K/Ca ratio in the
fruit which makes Ca deficiency more severe.
Where blossom-end rot is starting to become a problem in
fruiting vegetables there are several control measures that
can be suggested.
1. Maintain a good soil moisture content. In times of
severe drought as this year, irrigate more often
with less water per irrigation. This will eliminate
the flooding-wilting cycle and increase the amount
of calcium reaching the fruit.
2. Foliage sprays of calcium, using calcium chloride or
calcium nitrate can be used to supplement a limited
soil solution calcium supply. This may allow more
calcium to reach the fruit and prevent the
development of blossom-end rot.
3. Do not sidedress with fertilizers that contain
tremendously high ratios of NH4, Na, K and Mg.
These can be antagonistic to Ca uptake. This is
more important in extremely dry years such as this
one has been.
4. Before planting subsequent crops, make sure soil Ca
is adequate with all major and minor nutrients in
B. Using Rates of Maturity as a Management Tool
Extension agents and fieldmen who work with vegetables
are often asked about the length of time it takes from
flowering to harvest maturity for various crops. The answer
has to be qualified with two very important points involving
the growing season and the stage of maturity desired.
1. Growing Season
If the growing season is moderately warm and good soil
fertility and moisture are maintained, vegetable crops can
be expected to perform quite consistently within the limits
shown in Table 1. The plant does not clock calendar days as
we know them. Plants clock or integrate simultaneously ten
or twelve different environmental factors which influence
growth and development. As these accumulate the plant
responds with new roots, new or larger leaves, flowers
and development of fruit. Air temperature, soil tempera-
ture, relative humidity, soil moisture, the number of hours
of certain wavelengths of light at a given intensity, rela-
tive humidity, soil moisture, and various other factors
influence growth and development. Soil and air temperatures
are generally considered to have the greatest influence on
rate of growth.
Table 1. Approximate Time From Pollination To Fresh Market
Maturity Under Warm Growing ConditionsI
Bean, Bush 7-10 Pepper, Green 46-55
Corn, Sweet 18-23 Squash, Summer 6-7
Cucumber, Slicing 15-18 Squash, Winter, Acorn 55-60
Eggplant 25-40 Tomato, Mature green 35-45
Muskmelon 42-46 Tomato, Red Ripe 45-60
Okra 4-6 Watermelon 43-45
1Adopted from: Lorenz, C.A. and D.N. Maynard 1980
Knott's Handbook for Vegetable Growers, Second
Edition, John Wiley and Sons, New York.
If a grower planted beans every week throughout an
entire summer he would find that the plantings in the warmer
periods would reach harvest maturity on almost the same date
as many of the plantings made many weeks before when the
weather was cooler. He would also find that a large drop in
yield associate with plantings made in mid-summer as shown
in Table 2.
Green Beans in Relation to Time of
Gainesville, 1978. (Yield, Bushels per
-- L -I------- ~
Provider Contender Harvester Bush Blue Lake
(Courtesy Prof. L. H. Halsey, Vegetable Crops
In some crops such as sweet corn and peas for proces-
sing, these environmental factors can be recorded and used
for prediction of harvest maturity. A temperature base
line, derived from long term research studies, is used in
most prediction systems. After a given number of growing
units above the base line have been accumulated, the crop is
checked to be sure the crop development has reached the
stage predicted, and if it has, harvesting is started as
soon as possible.
2. Stage of Maturity
The term maturity has several meanings to the horticul-
turist, although most fruit type vegetables are consumed in
the immature stage. Botanical maturity indicates that the
fruit and seed are at fullest development; market maturity
is a stage which will allow for effective handling and
transportation from the field to consumer, and horticultural
maturity when optimum culinary value (taste, texture, color,
etc.) has been reached. The horticultural stage is often
referred to as "the fleeting moment of perfection", and all
of us who have had fresh picked, prime stage sweet corn just
out of the pot know what that means!
A few examples of the three types of maturity are:
Crop Maturity Category
Market Horticultural Botenical
Mature green to Hard ripe to Soft ripe to
Tomato hard ripe soft ripe early decay
Beans, Bush Slight to Very little to Pods dry,
moderate seed slight seed seeds hard
Okra Pods moderate Pods small, Pods
size, seeds seeds soft seeds hard
soft to firm
Maturity concepts are important management factors for
the grower-shipper, roadside market operator, and home
vegetable gardener.* Sometimes, but not always the market
and horticultural maturity stages can be the same, and that
is happiness for the consumer!
They can be helpful in planning labor and harvesting
supplies, scheduling harvest periods, and development oF
A. Chlorine Management
It Is recommended that all water that comes in contact
with produce (other than lettuce) in vegetable packinghouses
be chlorinated (1). Chlorination does not disinfect the
tissues of contaminated fruits or vegetables but it does
prevent the spread of decay-producing organisms in the water
of dump tanks, washers, and hydrocoolers. Chlorine should
also be used in cleanup water to sanitize grading belts,
packing lines, sizers, picking containers and other sites
that come in direct contact with the produce.
The aqueous chemistry of chlorine is complex. In
packinghouse water chlorine exists in both available and
unavailable forms. Only free (available) chlorine is
effective as a disinfectant. Free chlorine decreases as the
leaves, stems, soil and other debris increase in dump tanks
and hydrocoolers. It is suggested that free chlorine levels
be maintained between 100 and 150 ppm (mg/L).
Every packinghouse manager should have a test kit for
monitoring free chlorine levels, even if automatic
chlorination equipment and monitoring services are
contracted. Test kits that test only total chlorine are not
useful by themselves because total chlorine includes both
the available and unavailable forms. A DPD (N, N. Diethyl-
P-Phenylenediamine) kit is necessary to test for free
(available) chlorine. Some test kits allow the user to test
both free and total chlorine in less than 5 minutes. Other
kits provide a rapid test for free chlorine only. Unfor-
tunately, these kits test in the range from 0 to 2.5 or 3
ppm (mg/L). To use in packinghouse water tests, managers
must dilute the water sample one hundred times to bring
samples on scale. Water used for dilution should be
chlorine-free and distilled or deionized water would be
best. The dilution can be done simply by bringing 10 ml of
packinghouse water to 1000 ml (1L) with chlorine-free
water. Another alternative is to bring 1.25 fluid oz. of
sample water to a gallon with chlorine-free water. Diluted
samples can then be tested and readings multiplied by 100 to
reflect the chlorine concentration. For dump tanks,
chlorine concentration should be tested at least twice a day
and more often in especially dirty conditions. Dump tanks
and hydrocoolers should be emptied daily and thoroughly
cleaned of debris.
Poor chlorine management can be a serious problem in
vegetable packinghouses. Too many managers assume that
because they have automatic equipment the job is being
done. Prior to the freeze substantial decay losses occurred
in some tomato shipments. A check of packinghouses revealed
that free chlorine levels were as low as 0 ppm in some
As part of the Postharvest LET project, 15 counties will
soon be equipped with test kits to aid Florida vegetable
packers and shippers in chlorine management. County agents
can assist packinghouse managers, in cutting losses due to
poor chlorination by establishing programs to accomplish the
1. Make operators aware of the need for chlorination
2. Help operators locate a source of chlorine-free
water for dilutions.
3. Make periodic follow-up checks with your own test
kit to verify packinghouse findings.
Agents needing help in establishing these programs
should contact Dr. Mark Sherman.
1. Hicks, J. R. and R. H. Segall. Water Chlorination for
Vegetable Packinghouses. Vegetable Crops Fact Sheet,
VC-1. Supplies are available from the Vegetable Crops
IV. HOME VEGETABLE GARDENING
A. When to Pick the Garden Vegetable
Most garden vegetables cannot be enjoyed at their best
unless they are harvested at just the right time. In the
case of English peas and garden beans, two or three days may
make a big difference. Even with today's stringlesss"
varieties of string beans, the pods may tend to become
stringy after they have reached a certain stage.
"String" beans, or more appropriately "snap" beans, are
best quality when they snap readily and have soft pliable
tips. Seeds should be rather immature. Shell beans, of
course, must be left until the pods are well-filled with
The Lima bean is a type of shell bean. Gardeners should
check to see that there are well-developed yet tender seeds
in the pods before harvesting. They should check the
foliage carefully near ground levels for the earliest pods.
Likewise, Southern peas should have seeds developed, yet
picked when the pods are still green and tender. Some
southern pea pods should be harvested when seeds are
immature so that the pods may be "snapped" for added variety
to the cooked dish. Pole beans should be picked regularly
so that the vines will continue to set more pods.
Potatoes may be dug as soon as the vines begin to dry
out, although the tubers will keep on growing for some weeks
after. A few may be dug at a time, or the entire crop at
Head lettuce does not always have to be as hard and firm
as a head of cabbage before it is ready to eat. Young
lettuce leaves go well in a tossed salad.
Kohlrabi grows rapidly, so it must be watched to make
sure it does not get too large. Kohlrabi must be eaten
before the skin hardens, which means before the bulb gets as
big as a baseball. Radishes also depend on early picking to
be good and free from hotness and pithiness. Other root
vegetables, which easily may get too large and tough are
turnips, rutabaga, carrots, beets, and parsnips. Young
carrots are especially good, and they should be pulled when
tender and less than two inches in diameter.
Most cooking greens are ready as soon as leaves are
large enough to grasp. Pull off a few leaves from each
plant, leaving the bud-growth to replenish the supply. Use
beet greens when the attached beet root is only about 1 inch
Swiss chard is ready for the table when the outside
leaves are a foot high, although it is well to cut lightly
at first to keep the plants growing. When near maturity,
the outside leaves will have large midribs, which can be cut
out and used as somewhat of a substitute for asparagus, the
rest of the leaves being boiled like spinach.
Collard greens may be harvested in two ways. The first
is to pull the entire plant when about 2 feet high. The
second way is to remove leaves individually from the bottom
of the stem, called "cropping."
Summer squash must be picked before the shell hardens.
Zucchinis are at their best when not more than two thirds
grown. However, those that get old should not be discarded,
as various recipes utilize them. Never let squash stay on
the vine too long, as this depresses further fruit
Cucumbers should be harvested when young, tender imma-
ture) and still green. Yellow is a sign of over-maturity
and poor quality.
The members of the melon family are sometimes difficult
to determine when ready for harvest. Muskmelonss "slip"
from the vine at maturity and usually show slight color
change from green to orange. Bright yellow means over-
maturity and loss of flavor.
Honeydews turn from pale green to a subtle yellow-cream
color at maturity. Watermelons sometimes fool even the
experts. Each variety has its own characteristics to
indicate its flesh is sweet and ready to eat.
Other fruiting vegetables which may be harvested when
mature are tomato and strawberry. Peppers, eggplants, okra,
and sweet corn should be harvested at an intermediate
maturity stage. The point of harvest is especially critical
for sweet corn. When the silks first turn black, the
kernals should be plump, milky, and sweet. The sweetness
develops almost overnight, and disappears almost as
quickly. Sweet peppers may be harvested green or red, as
long as the pods are crisp, firm, and fresh.
It is important for gardeners to know all the signs, if
for no other reason than to stay one jump ahead of nature's
harvestors bugs, birds and raccoons.
B. Know Your Minor Vegetables Rakkyo
Rakkyo (Allium chinense G. Don.) is an onion relative.
It is also called ch'iao t'ou. It is important as a
vegetable in the Orient, and is grown and used mainly in
this country by people of Oriental origin. The plants do
not produce seeds and are propagated by bulb division. In
Florida, the bulbs should be planted in late summer, early
fall and the crop harvested in early summer of the following
year. Several small bulbs are obtained from each bulb
planted. Rakkyo bulbs are mainly pickled, some canned, and
others used as a cooked vegetable. The leaves have hollow
blades. Rakkyo should be grown as bulb-set green onions.
Harvest about 10 months after planting. Do not confuse with
wild leeks, or ramps, which have flat, bladed leaves and
grow well around the state.
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