CELERY SEEDBED DISEASES AND SUGGESTIONS ON
THEIR CONTROL

By

R, S. Cox

This report is based on research conducted
at the Everglades Station during the past
two years. Suggestions for disease control
are subject to change and modification as
further research might dictate,

EVERGLADES STATION MIMEO REPORT 56-6

Belle Glade, Florida

November 23, 1955

JI

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S~-6 -A

CELERY SEEDBED DISEASES AND SUGGESTIONS ON
THEIR CONTROL

R. S. Cox 1/

Success of the celery industry in the Everglades is dependent, in part,
upon the production of high-quality seedlings. Normally it requires two and one-
half to three months to produce seedlings for transplanting--virtually the same
length of time required after transplanting to the field. Due to the extremely
crowded conditions, diseases are much more serious in the seedbed than in the field.

Adequate controls for many of these diseases have been lacking. Another
deficiency in the program has been the fact that separate spray operations were
employed for such diseases as damping-off, bacterial blight and early blight. It
can be seen that where two applications per week were necessary for each disease,
adequate control might be difficult to obtain unless a grower was well-stocked with
spray equipment--a situation that seldom, if ever, exists.

This report on the disease problems in the celery seedbed with suggestions
on their control is based on research at the Everglades Experiment Station during
the past two years It should be borne in mind that suggestions for disease con-
trol in such reports as this are subject to changes and modification as further
research might dictate.

EFFECTIVE MATERIALS

1. Fusarium yellows
and Red Root

2. Nematode Root Knot

3. Damping-off

4, Bacterial Blight

5. Early Blight and
Late Blight

6. Weeds

Chloropicrin
Methyl bromide

Methyl bromide, Chloropicrin

Pre-seeding: Methyl bromide
After seeding Spergon, Fermate
Tribasic copper sulfate, Copper A,
Terraclor

Agrimycin, Agri-strep,
Phytomycin, Tribasic copper
sulfate, Copper A.

Dithane, Parzate, Zerlate
(The neutral coppers give fair control)

Methyl bromide

SUGGESTED CONTROL PROGRAM

1. Soil Fumigation:

Of some 20 materials tested, methyl bromide and chloropicrin stand out
as pre-seeding soil fumigants. Based on all-around performance, methyl bromide
appears to be superior to chloropicrin--particularly against weeds, Rhizoctonia

1/ Associate Plant Pathologist, Everglades Experiment Station, Belle Glade, Florida

THE DISEASES

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damping-off and internal stem discoloration, The advantage of chloropicrin over
methyl bromide is the fact that fumes may be confined with a water seal rather
than with a special cover, although the covers provide better disease control.

a. Rate of application: Apply methyl bromide at the rate of 18-24
pounds per bedi/ and chloropicrin at 2 gallons per bed.

b. Preparation of Seedbed: Prepare the beds as for seeding. It is
important that the soil be free of plant refuse (stems, roots, etc.) and lumps
or clods. Soil moisture should be at the optimum level for seeding.

c. How to Treat: Special equipment is necessary to apply both materials.
Directions and assistance can be obtained from the local distributor as well as
from Extension and Experiment Station personnel. It is important to remember that
the methyl bromide gas must be confined with special covers; whereas, chloropicrin
fumes may be confined with the same covers or with a water seal.

d. WJhen to seed: In the case of methyl bromide wait 3 to 7 days after
treating before seeding. Tith chloropicrin the waiting period may be somewhat
longer. The "eye and nose" test is generally reliable in determining if the chloro-
picrin gas has escaped from the soil. It should be noted that both gases remain
in the soil longer in cooler weather.

e, How late to treat: Based on observations it appears that all beds
seeded before October 1 should be treated at the full dosage. After that time the
rate may be cut in half, or eliminated entirely unless the plant bed site is known
to be badly diseased.

f. Precautions: Both methyl bromide and chloropicrin are poisonous
gases and precautions on the company's labels should be followed closely.

2, Spray Program:

A highly desirable spray program would be one that would control damping-
off, bacterial blight and common blight in one operation. We are suggesting several
mixtures that so far show no injury to the plants and appear to control all the di-
seases in question.2/
a. First preference: Spergon (4 lbs.) plus Streptomycin (50 ppm.) plus
Dithane or Parzate (2 Ibs.). Note: Until further information is available, Di-
thane and Parzate should not be mixed with Spergon until the plants are six weeks
old.

b. Second preference: Fermate (4 lbs) plus Streptomycin (50 ppm) plus
Dithane or Parzate (2 lbs. of the powder or 2 quarts of the liquid plus 3/4 lbs.
zinc sulfate).

c. Third preference: Neutral copper (4 lbs.) plus Streptomycin (50 ppm)
plus Dithane or Parzate (2 lbs. of the powder). Note: Mixture of copper and Di-
thane or Parzate appears to cause a slight bronzing of the leaves of plants less
than six weeks old. So far, no serious damage has resulted.

I/ Standard celery plant beds are of the dimension, U' x 3001,

2/ All rates are for 100 gallons of spray, and 10 gallons of spray are required
to the bed.

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d. Fourth preference: Spray Tith Tribasic copper or copper A alone un-
til the plants are six weeks old then switch to the combination of your choice
listed above. Note: We believe that this schedule may eventually prove to be the
best one,

e. Fifth choice: Terraclor (PCNB)(4 Ibs.) plus Streptomycin (50 ppm)
plus Dithane or Parzate (2 lbs, of the powder or 2 qts. of liquid plus 3/4 lbs.
zinc sulfate).