COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS
STATE OF FLORIDA
COLLEGE OF AGRICULTURE. AGRICULTURAL EXTENSION SERVICE
UNIVERSITY OF FLORIDA, AND a COUNTY AGENT AND
UNITED STATES DEPARTMENT Vegetable Crop Specialists HOME DEMONSTRATION WOR
OF AGRICULTURE, COOPERATING GAINESVILLE, FLORIDA
No. 9 VEGETARIAN February 15, 1951
FREEZING INJURY: Br-r-r-r-, wasn't it?
May as well get something good out of this 'unusual' weather. Recognizing that
the gamble is always there on tender crops, let's have a look at the nature of freez-
ing injury on some of the hardy plants. It comes from the manuscript of a publicatim-
to-be by Dr. A. H. Eddins,Plant Pathologist in Charge, Potato Investigations Labora-
"Crucifers are hardy plants but may be injured or killed by freezing depending
upon age of the plants when frozen, lowness of the temperature and length of ex-
posure. Cabbage tissue freezes at 31TUF. young plants are injured more severely by
freezing than older ones.
"Leaf tissues tolerate formation of ice and thawing and recover without injury
provided they are not frozen too hard and do not remain frozen too long. Frozen
areas become water-soaked when the ice melts and water accumulates in the intercellu-
lar spaces. If the cells are still alive, some of the water will reenter them and
the tissues will appear wilted. If the cells are killed, water evaporates causing
the tissues to dry or it remains and the frozen parts become a soft, leaking mass.
Tissues injured but not killed by freezing turn pale green to white.
"The pith of a stem of a severely frozen plant which has survived becomes
spongy and turns white. Later the pith dries and shrinks and the stem becomes hollow;
functional parts left are the outer tissues which include the vascular bundles and
"Common injury to heading cabbage consists of death and discoloration of parts
of the foliage leaves and the appearance of discolored, wilted and soft spots on tops
of the heads which make them unsalable. When soft rot bacteria enter tissues killed
by freezing the affected parts soon decay. Freezing injuries also serve as points of
entrance for the fungus causing sclerotiniose.
"Losses due to freezing of cabbage, cauliflower and broccoli in November, 1950
were the greatest ever recorded in Florida. (Hastings)..Most plants were young and
tender and not conditioned to withstand low temperatures. Seedlings which were be-
ginning to emerge from the soil and older cabbage plants nearing maturity escaped
serious injury. Likewise, plants situated in seedbeds and fields in which the soil
had been made wet by irrigation were not damaged as severely as those growing in
November and December weather delayed production of these crops in the Hastings
area about six weeks. Dr. E. N. McCubbin, Horticulturist, Potato Investigations
Laboratory, says that where broccoli normally grew 12-15" in height over a period of
60 days, this year it grew 6-8" and developed small heads with no room for side
shoot growth. He plans observations on what happens when this central cluster is
pinched out. It was about the same story on cauliflower--small plants, small heads,
and no leaves of jacket size.
STING NEMATODE: not root knot.
Here's a new slant on the nematode situation through work of Dr. A. N. Brooks,
Plant Pathologist in Charge, Strawberry Investigations Laboratory, Plant City. He is
interested in determining the distribution of the sting nematode,Belonolaimus gracilis
Steiner on strawberries. It has already been reported from Seminole, Hillsborough,
Hardee, Polk and Manatee counties.
"This nematode lives outside of the roots and feeds on the younger roots and
root tips, resulting in a system of old coarse, stubby roots and no fine feeders.
Leaflets on affected plants are small and have dark brown edges, a common symptom of '
root injury. Plants gradually decline in size and after several weeks may die. Small,
infected spots may be found in the field to begin with, which gradually increase in
size--usually in a circle."
If you observe this pattern, and can satisfy yourself that the cause is not
fertilizer burn or incorrect pH, select an affected live plant, get about a pint of
soil around the roots and place the soil and plant in a shipping container. If the
soil is rather dry, dampen it. (Mail to Dr. Brooks, Strawberry Lab.Box 5$2, Lakeland)
WATERIMELONS: ice box and seedless types--and rats.
Queried Dr. G. K. Parris, Plant Pathologist in Charge, Watermelon Investigations
Laboratory, Leesburg, on ice box types for the gardener. No one seems too enthusias-
tic about the possibilities but chances are you'll have some of the same questions
directed to you.
we've e grown the New Hampshire Midget, a small, round, striped, white-seeded
melon, weighing 10 to l-pounds or less. It is relatively early and has fair
quality. The rind is thin, and there seems to be no resistance to wilt and other
"The Japanese Seedless is a new development gardeners may ask about. This is an
Fl hybrid, round, dark green and weighs 10 to 15 pounds. One ordinary melon plant
should be planted along with every 5 to 10 seedless plants to serve as a pollen pant
Dr. Parris passed along the reminder that the cold weather reduced the food
supply for mice and that watermelon seed are especially attractive. If the soybean
lecithin spreader recommended in Circular S-17 is not available, mineral oil, corn
oil or some other vegetable oil can be substituted.
DDT-OIL SPRAYS FOR CORN EARWORT CONTROL
Three Florida Agricultural Experiment Station entomologists are working under an
agreed plan in a concerted effort to get even more accomplished on effective control
measures for the corn earworm---definitely the success of which stands as a trumD
card in the sweet corn deal Dr. E. G. Kelsheimer, Bradenton, Mr. N. C. Hayslip,
Ft. Pierce, and Dr. J. W. Wilson, Sanford, (check their Bulletin h66, January,1950)
are cooperating to get the answer to just where the new DDT-oil sprays fit into the
Florida picture. Several agents have inquired on the present status. Dr. Wilson
gives---"DDT-oil spray for earworm control continues to be in the trial stage in
Florida. Other areas (Vest) report success with 2- gallons of horticultural oil of
85-90 viscosity, used with 3 quarts DDT 255, made up to 25 gallons with water. This
is applied at the rate of 25 gallons per acre, 60 pounds pressure, using four .026
orifice fan-type nozzles per row, at the first appearance of silks and 2 to 3 days
"Number and timing of applications, gallonage, number and type of nozzles,
pressure and formulation are not as yet determined for Florida conditions. VHe hope to
have some tentative suggestions after the coming spring season."
USE WATER ;JITH THAT MUCH SALT? -- heard that one yet?
When reminded that county agents too often run into questions concerning just
how much salt in irrigation waters can or cannot be tolerated by plants,Dr.P.J.West-
gate, Associate Horticulturist, Central Florida Station, Sanford, offered the follow-
ing: "These are the best answers I am able to give at the present time. I hope thy
are better than no answers at all, If any of your observations should contradict I
would very much like to bring my thinking in line and up to date.
"Very salty water from artesian wells should not be used for irrigation. One
well near Sanford shows 8000 p.p.m. C1 and is capped. 900 p.p.m. C1 (or 1260 p.p.m.
NaCl) is about as high a salt content as can be used for continued irrigation in th:
area. There is no one concentration of soluble salts which divides 'good' and 'bad'
irrigation water. A lot depends on the amount used, duration of use, temperature,
evaporation, humidity, crop, hardpan, drainage, soil type, etc.
"The following table will give some idea of the quality of water depending on
the soluble salts concentration, expressed in various ways.
Excellent to Good Good to Injurious Injurious to Unsatisfactory
0 to 700 700 to 100 2100 and up* Total soluble salts (p.po.m)
0 to 420 420 to 1260 1260 and up. NaCl (p.p.m. salt)
0 to 300 300 to 900 900 and up. Cl (p.p.m. chlorides)
0 to 100 100 to 300 300 and up. Conductivity (iHOS X 10"5)
"For our artesian well waters the following approximations hold fairly well:
(1.) Conductivity (MHOS X 10-5)X 3 equal p.p.m. Cl1
(2.) X 7 equal p.p.m. total soluble salts.
(3.) p.p.m. Cl X 1.4 equal p.p.m. iaCt
"Artesian wells around Sanford remain constant in salt content regardless of
season or year, even though some wells are more salty than others. Continuous use
does not change their salt content. This is not always the case with pumped wells
near the coast, such as at Homestead or Clearwater, where salt water intrusion may
come in from the ocean. Our inland artesian wells are dissolving out their salts
from ancient salt deposits left by former inland seas.
"In rDiagnosis and Improvement of Saline and Alkali Soils', U. S. Regional
Salinity Laboratory, Riverside, California, crops are listed in three groups depend-
ing on their tolerance to salt; i. e.
I. Good Salt Tolerance : Beets, kale, cotton, etc.
II. Moderate Salt Tolerance : Tomato, lettuce, pepper, etc.
III. Poor Salt Tolerance : Celery, cabbage, beans, etc.
"Plants in Group III have only a slight tolerance and a conductivity of the
saturation extract (soil solution) equal to 400 MHOS4 X 10-(0O.1% or 1000 p.p.m.
salt in medium textured soil) may cause signiicant reduction in growth.
"At Homestead, beans were the first vegetable to die out with salt intrusion,
cabbage next, then tomatoes, and finally beets. Here at Sanford beans and corn
are very sensitive and will not stand as much salt as celery, cabbage and escarole.
Vegetables on marl and muck soils will stand more salt than on sandy soils.
"Once the soil solution is loaded up with soluble salts it is dangerous to dry
out the soil, since reducing the percentage of moisture by 50% will double the con-
centration of soluble salts in the soil solution.
"Keep from turning on the salty wells as long as possible but, 'once you turn
them on don't turn them off', is*the way one celery farmer phrased it. The dry
farmer and the wet farmer get by, but the farmer who fluctuates his moisture gets
hurt." (Sad but true.)
IRRIGATION ON SANDY SOILS--
Dr. Victor F. Netls, Assistant Horticulturist, Florida Agricultural Experiment
Station, Gainesville, recently summarized a six-year study on irrigation (overhead)
of beans, onions, corn, cabbage, peas and broccoli in the Gainesville area.
"In general, 1/2 to 3/4 acre inch of water every six days, either applied by
sprinkler or as recorded rainfall has been satisfactory. Irrigation was not always
essential or economical but in some years it was the difference between success or a
complete crop failure. For example with beans in 1946 irrigation resulted in little
benefit but in 19-L7 the yield was increased nine times. Sweet corn yields have been
increased in both dry and normal years.
"Large applications of water will leach many plant nutrients, while too small
an amount coupled with too frequent applications will result in shallow rooting of
the crops. These frequent applications are also uneconomical,
"Although plants can use the soil water supply as well from field capacity down
to near the wilting point, one must plan irrigation operations to apply water before
the soil reaches the wilting point. Current rainfall records are of great assistance
in determining when to irrigate. Nothing, however, completely replaces experience.
"Some of the factors affecting frequency of application are type of soil,
humidity, winds, cloudiness, age and type of vegetable. The rooting systems of
celery, lettuce and cabbage are classified as shallow or near two feet. The rooting
system of cucumber goes to a medium depth of four feet while tomatoes and watermelons
extend to approximately six feet
"A question often asked is what time of day should irrigation be made. Actual-
ly, it should be when it is most convenient and economical. Generally less evapora-
tion loss occurs during the night and such diseases as late blight of tomatoes and
mildew on cucumbers might be lower if water was applied in the early morning. The
amount of equipment often makes this impractical.
"Irrigation cannot do it all. Good cultural practices including adequate ferti-
lization, incorporation of orgiaic matter, and spray schedules for disease and insect
control must continue. Irrigation is only an adequate insurance for better crops
when all the other factors for plant growth are favorable."
Dr. A. H. Eddins, Plant Pathologist in Charge, Potato Investigations Laboratory,
Hastings, wrapped up this compatibility problem rather neatly the other day. Glad to
see it? Us too. (Not Compatible, Questionable and Compatible.)
Dr. Eddins states in the source of this information, "based mostly on informa-
tion submitted by plant pathologists of the Florida Agricultural Experiment Station
for publication in the 1950 revision of the Handbook on Pesticides and Their Uses in
Florida Agriculture." (May add that some combinations of insecticides and phygon
may cause injuries to crops. See seedbed late blight on tomatoes.)
VEGETABLE FIELD DAYS COMING UP
Recognizing that well-organized vegetable field days of the Florida Agricultural
Experiment Stations give invaluable information to agents and growers, we circular-
ized on January 23rd for some approximate dates you could line in red and watch
for-- The latest guesses we have follow:
Belle Glade: ?
Homestead : 'Maybe 3rd week February, pot
Sanford : 'Sometime in March unless sudi
Leesburg : 'Approximate date June 61
Plant City : ?
Hastings : 'Tentative date chosen is Mar
Bradenton : 'Around April 201
Gainesville: 'Probably second week in Mayl
LIME IN CR LIE OUT---nabam
You'll be delighted to know that finally this business of omission of lime in
nabam formulations for tomato late blight control is straightened out as of early
February---in the pesticide manual manuscript. O.K., so you knew it. No lime with
F. 3o JAMISON
Vegetable Crop Specialist
AVERAGE PLANT FOOD CONTENT OF FERTILIZER MATERIALS
t t'Reaction per 100 Ibs.
'Percent Plant Food Availability' Material
A mmo-Phos B
Nitrate Soda Potash
Citrus seed meal
Cocoa Shell Meal
Tung Nut meal
Steamed Bone Meal
Raw Bone Meal
Ground Rock Phosphate
' N 'P22o
' Acidit' Alkalinity
Sulfate Potash Magnesia
Calcitic Limestone -
Copper Oxide -
Iron Sulfate -
Manganese Sulfate -
Zinc Sulfate -
Aluminum Sulfate -- -- -
(Tongue-in-cheek, recognize variability of
Quickly, 7-10; Mod. Quick, 15; Slowly, 21
availability--Rapidly, 3 to 5 days;
; Very Slowly, 30-35 days--under the very
' K120 Oxides'
-- -- Moderately
-- -- HModera tely
-- -- Rapidly
S -- Rapidly
.5 -- Slowly
2.5 -- Slowly
5 -- Slowly
1.5 -- Slowly
.8 -- Mod. Slow
0 8.5 Ca Slowly
2 -- Moderately
1.5 -- Slowly
15.5 -- Slowly
1.5 t.5 Ca Very slow
5 -- Slowly
0 33 Ca Mod. Quick
0' 31.5 Ca'Slowly
-430 Ca, 15Fe'Quickly
-- Very slowly
20 Ca Quickly
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