COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS
STATE OF FLORIDA
COLLEGE OF AGRICULTURE.
UNIVERSITY OF FLORIDA. AND
UNITED STATES DEPARTMENT OF
V -gctablc Crop Specialists
AGRICULTURAL EXTENSION SERVICE
COUNTY AGEtIT AiND
HOME DrMONSTRATION WOR'.
TO: COUNTY AGENTS, ASSOCIATES AND ASSISTANTS
Host Plants for Cabbage Black Rot
Cabbage Varieties and Diseases
Black Heart in Celery, Endive and Escarole
I. FLOODING PRACTICES--WHAT ARE THE ADVANTAGES?
Insect Control -- Mr. Genung states that flooding fields for
trol cutworms 100 percent if there is no trash or litter for them
cutworm moth will not lay eggs on flooded land.
Wireworms are also controlled by flooding; however, a longer
hours is necessary.
48 hours will con-
to climb on. The
flooding than 48
Disease Control -- Control of celery pink rot and lettuce Sclerotiniose disease
caused by Sclerotinia can be had by flooding for six weeks. Flooding causes the
Sclerotia to rot and breaks the reproductive cycle of the fungus.
Flooding of organic soils is an approved soil conservation practice to reduce
subsidence through oxidation and a conservation payment can be received for flooding.
Dr. Wehlburg states that there is little danger of spreading black rot bacteria
by flooding because these bacteria need cathage plant debris to live on and this
plowed in debris rots very rapidly. He states that about 8 weeks waiting period
between flooding and planting should free the soil from any pathogenic bacteria that
might have been in it.
The Fusarium wilt fungus may be spread by flooding.
Complete soil submergence and for a duration of at least six weeks is necessary
for best results. This practice works on all soil types.
II. HOST PLANTS FOR BLACK ROT OF OA "ZGE
Dr. John Darby, Central Florida Experiment Station, has found two weeds of the
area that are hosts for the black rot bacterium (Xanthomonas campestris). This
partially explains the relatively high incidence of the secondary stages of the
disease in cabbage, broccoli and cauliflower in Florida, even where seed has been
hot water treated. These two weeds are Chinese Mustard (Brassica juncea) and wild
radish (Raphanus raphanistrum). These two weeds have been found in the Hastings
area and are no doubt present in other areas of the state.
III. BLACK SPECK OF CABBAGE HEADS
This disorder has caused serious loss to cabbage grown in the Sanford area and
has been observed to lesser extent in other areas of Florida. No pathogenic organ-
ism can be associated with it. It occurs on mature heads and becomes more severe
after harvest and in transit. The small black specks are described by Dr. Darby as
usually following leaf margins and depressions in the leaf surface. Specks may
occur on every leaf all the way to the core or specks may occur on one leaf with no
specks on the leaf below. In a Variety Trial at the Central Florida Experiment Sta-
tion during the winter and spring of 1965, Badger Market, Globe and Marion Market
showed the lowest incidence with 0 percent to 7.5 percent at 106 days of age. The
hybrids King Cole, Market Topper, Market Prize, Market Packer and Harris 63-74 all
showed from 90 percent to 100 percent black spot at 106 days of age. With the in-
creased popularity of hybrid cabbage, this disorder could become quite serious.
IV. BLACK HEART IN CELERY, ENDIVE AND ESCAROLE
There has been serious losses this winter from black heart in endive and esca-
role. This is the same disorder as occurs on celery and can be controlled with the
same treatment. Control should be on a preventative basis. Work by Dr. Geraldson
at Bradenton and subsequent work by Drs. Westgate, Forbes and Burdine have confirmed
that the basic cause is from a calcium deficiency in the plant. Sprays with soluble
calcium salts applied to the heart of the plant is the best control. Either 5 pounds
of calcium chloride or 10 pounds of calcium nitrate per 100 gallons of water weekly--
watch for black margins of heart leaves and begin sprays when they first appear.
V. SHORT SUBJECTS
A. Copper fungicide applications this past winter at Belle Glade on cabbage and
at Zellwood on carrots indicate that where copper was not used in the spray program
these two crops were more resistant to cold.
B. The Vegetable Field Day at the Belle Glade Station will begin at 9:15 A. M.
on May 4, 1965. We previously announced it for 10:00 A. M.
C. A lot of cabbage leaf browning in the Hastings area this spring has been
attributed to black rot and other diseases. Dr. Hensel has definitely attributed
most of it to potassium deficiency. Particularly on lighter soils with low amounts
of potassium applied and following heavy rains. Dr. Hensel recommends side dressing
with a mixed goods which contains both potassium and nitrate nitrogen.
D. Size and spacing of cabbage transplants.--It looks like from work in pro-
gress at Hastings that grading cabbage plants into uniform sizes may pay. First
harvest yields increased linearly as size of plant and spacing increased. Remember
a 16" spacing must produce twice the size plant to equal the yields of an 8': spacing.
E. Pesticides toxic to Bees.--USDA and University of California workers have
classified 124 pesticides as to their toxicity to Honeybees; 37 were highly toxic,
19 moderately toxic and 68 relatively non-toxic. The non-toxic group were evenly
divided between insecticides, fungicides and herbicides.
Take every reasonable precaution to apply pesticides so that a minimum of in-
jury will occur to bees. We blame bad weather or the variety for poor fruit set on
vine crops when in most cases it is from low bee activity.
F. Chemical Bird Management.--The bird communication process of "flock alarming"
is used by feeding a few birds food which has been treated with chemicals which make
them utter distress calls which repel other birds in the flock. The chemicals are
registered for control of sparrows, starlings, cowbirds, pigeons and blackbirds,
around buildings and feed lots. Chemicals are for sale only to be applied by trained
pest control operators.
G. Wind Breaks.--Dr. Forbes at the Central Florida Station is evaluating wind
break plants including rye, blue lupine, sorgum (wind breaker), oats and sunflower.
Preliminary results indicate that for early fall, planting sunflowers are best, for
later in the winter or early spring, rye or a mixture of rye and oats appear best.
H. Recent Pesticide Registration Changes.--
1. Dosage of 2-capryl-4,6-dinitrophenyl crotonate (Karathane) on cucumbers
has been reduced from 0.5 pound of active per acre to 0.25 pound of active per acre.
The interval between last application and harvest remains at 7 days.
2. Dieldrin use on carrots was removed from registration on March 15, 1965.
3. "Zinc ion + manganese ethylene bisdithiocarbamate complex"--this is the
name which has been accepted by the Pesticides Regulation Division of The United
States Department of Agriculture for a compound trade named Dithane M-45. For clari-
fication, this compound is chemically different from the two other mixtures of maneb
-- zinc salts which are sold under the trade names of Dithane M-22 Special and Manzate
D. This compound requires a separate registration from the other two compounds
mentioned and from maneb and zineb. Dithane M-45 is registered on peppers and toma-
toes at 1.8 pounds of actual per acre and 1.5 on tomatoes, with the limitations of
"do not apply after fruit buds form." Potatoes were registered at 1.6 pounds with
with "no time limitation." On March 15, 1965, cantaloupes, cucumbers, melons, pump-
kins and squash were added to this registration at a dosage of 2.4 pounds of active
ingredient per acre, with the limitation "do not apply after edible parts begin to
form." Onions for dry bulbs were also labeled at 2.4 pounds of active ingredient per
acre with a 7 day interval between last application and harvest with directions, "do
not apply to exposed bulbs." These registrations are limited ones and are established
on the basis of no residue remaining on the crop. Growers should use this chemical
with this in mind.
We have just received notice that the Food and Drug Administration has granted
the following tolerances for Dithane M-45 on melons:
7 ppm on the whole fruit with no residue present in the edible pulp
after peal is removed, with no time limit between last application and
harvest. The melon group includes cantaloupes, Honey Dew melons,
muskmelons, pumpkins, watermelons, winter squash, but it does not in-
clude cucumbers and summer squash. These latter two crops can be consumed
with the peal intact and hence a no residue registration for edible portion
is out of the question. Dithane M1-45 can be used on cucumbers and summer
squash until fruit begins to form.
F. S. Jamison, Head
Vegetable Crops Department
1/ James Montelaro
Associate Vegetable Crops Specialist
Mason E. Marvel
Associate Vegetable Crops Specialist