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 Title Page
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 Seedbed diseases and their...
 Field diseases and their contr...
 Literature cited
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Group Title: Bulletin University of Florida. Agricultural Experiment Station
Title: Etiology and control of celery diseases in the Everglades
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00026866/00001
 Material Information
Title: Etiology and control of celery diseases in the Everglades
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 27 p. : ill. ; 23 cm.
Language: English
Creator: Cox, Robert S ( Robert Sidney ), 1918-
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1958
Copyright Date: 1958
Subject: Celery -- Diseases and pests -- Florida -- Everglades   ( lcsh )
Celery -- Diseases and pests -- Control -- Florida -- Everglades   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Includes bibliographical references (p. 27).
Statement of Responsibility: by R.S. Cox.
General Note: Cover title.
General Note: "A contribution from the Everglades Experiment Station."
 Record Information
Bibliographic ID: UF00026866
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltuf - AEN7725
oclc - 18287565
alephbibnum - 000927022

Table of Contents
    Front Cover
        Front Cover
    Title Page
        Page 1
    Table of Contents
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
    Seedbed diseases and their control
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
    Field diseases and their control
        Page 23
        Page 24
        Page 25
        Page 26
    Literature cited
        Page 27
    Back Cover
        Page 28
        Page 29
Full Text

Bulletin 598 July 1958

A Contribution from the Everglades Experiment Station

Etiology and Control of Celery Diseases

in the Everglades

By R. S. Cox

p -
i -1 .1 T ~. r W

.) .. .

Fig. 1.-Gross effect of severe early blight infection. Note yellowing of
lower leaves. Rows with numbered stakes were treated as follows: 13,
Agrimycin; 12, Dyrene plus tribasic copper sulfate; 3, nabam plus zinc sul-
fate. The rows without stakes were not sprayed.


Bulletin 598 July 1958

A Contribution from the Everglades Experiment Station

Etiology and Control of Celery Diseases

in the Everglades

By R. S. Cox


Single copies free to Florida residents upon request to

SYMPTOMATOLOGY .... ........-.-.... ................ ..... ...--.......... 3
Dam ping-off .........---- .. ......... ..............-- --. .........- ........... 3
Root Knot ..................... ....---------....... ...... --.....-- .... 4
Red Root ............ ... ................ --------.. ......... ....... 5
Early Blight .............-...-.....-- ... ..------................... .... 7
Yellows .................... ..-..-..... -. -------- ...... ....... ..--- 7
Bacterial Blight ....- ..--..... -----..........-.... ............----- .....-- 7
Late Blight ..-....-- ...----..- .....-- ..--- ...... ...... .................. 9
Anthracnose .----.... ..........-------------.. --..--.--- ........... 9
Rooting Failure .....- ...... ..-- -- .......-------..... -.........-.....-.... 9
ETIOLOGY ....---.....-- ...-- .. .-- --. ........-...-...... ------------ .........-- ......- ..... 9
Isolations and greenhouse pathogenicity trials ..................................... 10
Identification .-......--....---....--...---....----------- ------ 12
SEEDBED DISEASES AND THEIR CONTROL ............-............ ......-- --............. 12
Soil Treatment .---.-.....- ----.-....-...- .........---......----- ........... 14
Foliar Sprays ....... --......--.. ..... --..----- .................. 20
FIELD DISEASES AND THEIR CONTROL ...-......................... ..-..--...--- ..-- 23
Test No. 1 ..........--- -...-.. ... ....... .----....- -... -... -... ... .. 23
Test No. 2 ...---.....-- ..---....--...- ....--...-.... .- -............ 25
SUMMARY .........--.............-- ...-.. ...-- ..-...... ------ -------------- 26
LITERATURE CITED ....--...--....--....---.---...-- -- -----. ............ 27

Etiology and Control of Celery Diseases

in the Everglades

By R. S. Cox
Formerly Associate Plant Pathologist, Everglades Experiment Station

The celery industry in south Florida is a complex two-phase
process consisting of seedbed and field operations. Although
the duration varies with the season, each of these operations
constitutes an approximate three-month period. Thus, six
months are required normally to produce a crop of celery. Seed-
beds in recent years have been started as early as May and suc-
cessive plantings are made into November and December. The
first crop usually comes off in December and celery is harvested
into June of the succeeding year. Thus, the industry not only
has become a year-round operation but actually comprises as
much as a two-month overlap from year to year.
Diseases constitute a serious limiting factor in celery pro-
duction both in the seedbed and in the field. In fact, successful
production is dependent upon control of these diseases. Ac-
cepted control programs appeared to be inadequate. This was
due, in part, to improper methods of application (coverage).
In addition, the causal relations of some of the diseases were
not understood clearly. As a result, it was not uncommon for
a grower to be spraying for a disease of mistaken identity.
This often led to mis-use of materials.
Several needs were apparent: 1) clarification of symptom-
atology; 2) establishment of causal relations where necessary;
and 3) development of a "catch-all" spray program-one that
would ensure protection from all diseases in the seedbed and in
the field. This bulletin presents the information gained from
a research program covering the period 1954-57 that was de-
signed to fill these needs.

Damping-off.-Due to the fact that seed are sown on the soil
surface, pre-emergence damping-off is relatively unimportant in
the celery seedbed. As would be expected however, due to the
three-month duration of a seedbed, post-emergence damping-off
is a serious problem. It occurs in two distinct phases: early post-
1 The writer is indebted to Nelson Nelms, field assistant, for supervision
of field work and to Henry M. Spelman III for assistance in photography.

4 Florida Agricultural Experiment Stations

emergence and late post-emergence. Both are more prevalent
and distinctive on plantings made before mid-September than
on later ones.
Early post-emergence damping-off occurs soon after the seed
germinate. Up to 50 percent of the seedlings may be lost dur-
ing this time. No definite pattern is involved; seedlings damp-
off at random throughout the bed.
Late post-emergence damping-off is the most spectacular and
probably the most serious phase of the disease. Unless adequate
control practices are followed, entire plantings may be lost.
This phase of the disease is characterized by the development
of circular areas of dead plants which gradually increase in
size (Fig. 3). Two or more such areas frequently coalesce,
resulting in large, irregularly shaped spots. An interesting
feature of this disease is that infection occurs not only on the
stem of the plant at soil level, but, more often, well up on the
petioles (Fig. 3). In the latter case each petiole must be affected
individually before the plant is killed. Affected tissues of the
petiole become watersoaked and collapse in a manner typical
of damping-off.
Root Knot.-Though principally a seedbed problem, this dis-
ease also occurs in the field. Affected plants are stunted and
chlorotic. Typical root knot galls develop on the roots.

Fig. 2.-Inspecting celery plots during a growers' field day.

.4*- a B : .

Etiology and Control of Celery Diseases in the Everglades 5

Red Root.-This disease is ubiquitous both in the seedbed
and in the field. It derives its name from the reddened appear-
ance of affected rootlets. Diseased areas extend back from the
root tip for distances up to one inch. Brown to reddish bands
also occur along the diseased roots. Up to 100 percent of the
root system may be involved.
The full importance of this disease is not clearly known. It
is undoubtedly a serious problem in the seedbed, but once es-

Fig. 3.-Rhizoctonia damping-off. Upper, circular patterns in the seedbed.
Lower, lesions on petioles.


Fig. 4.-Upper: Early blight symptoms (note
size of lesions and chlorotic areas). Lower: Bac-
terial blight symptoms (note angular appearance of

Etiology and Control of Celery Diseases in the Everglades 7

tablished in the field the plant appears to "grow out". Plants
showing 100 percent root infection at time of transplanting
may become practically disease-free as new roots are formed.
The summer pascal varieties are more tolerant of this disease
than are the golden ones.
Early Blight.-As with most leaf diseases of celery, early
blight, caused by Cercospora apii Fres., is initiated as a tiny cir-
cular spot, reddish brown in color. The spot rapidly enlarges
to an ultimate size determined by weather conditions and number
of spots on the leaf. A single spot may cover practically an en-
tire leaf blade or petiole; it may be circular in outline or quite
angular; it may be paperish in texture or watersoaked, thereby
providing a greasy appearance.
Under moist conditions, three features set early blight lesions
apart from others. These are their large size, the dark gray
centers resulting from a profusion of conidiophores and conidia
and the large chlorotic areas surrounding the spots (Fig. 4).
The disease is more prevalent on the lower portion of the
plant, where free moisture may persist 24 hours of the day.
Under such conditions the leaves become completely yellowed
(Fig. 1).
Yellows.-This disease has been observed only in a few iso-
lated instances. Once established in the seedbed, soil fumigation
becomes necessary or a new plant bed site must be selected.
The golden varieties are more susceptible than the pascal varie-
ties. The disease is first evidenced by a chlorosis of the leaf
resulting in vein clearing. A vascular discoloration is usually
associated. Infected plants become severely stunted and may
eventually die.
Bacterial Blight.-Although bacterial blight, caused by
Pseudomonas apii Jagger, appears to be primarily a seedbed
problem, it occurs to some extent in the field. The damage it
inflicts in the field is not clearly understood. It is believed that
it frequently occurs in the same lesion with, and overrun by, the
early blight organism (2).
Bacterial blight lesions may be confused easily with those
of early blight. Characteristically, they are smaller, more angu-
lar, have a deeper red color and are more watersoaked in ap-
pearance than are the early blight lesions (Fig. 4). Neither
do infected leaves develop chlorosis as rapidly nor to the same
extent as those of early blight. Still another, and the most un-
usual, method of identification is the detection of a characteristic

8 Florida Agricultural Experiment Stations

Fig. 5.-Anthracnose symptoms. Early stages at bottom,
advanced stages center and top.

Etiology and Control of Celery Diseases in the Everglades 9

odor given off by diseased plants. To some the odor is sweetish
in character, to others it is reminiscent of malt, while to still
others it is suggestive of scalded celery.
Late Blight.-Late blight, caused by Septoria apii (Briosi &
Cav.) Chester, is of minor importance in the Everglades. An
important diagnostic feature of this disease is the occurrence
of black fruiting bodies (pycnidia) near the center of the lesion.
Anthracnose.-This disease, caused by Colletotrichum sp.,
was described only recently (2,3). As with the other leaf dis-
eases, symptoms appear initially as small reddish-brown spots;
these gradually enlarge in irregular outline to an area compris-
ing one to three millimeters in diameter (Fig. 5, lower). Their
small size is an important diagnostic feature. With age, the
center of the spot becomes whitish in color and paperish in tex-
ture (Fig. 5, center). Merging chlorotic areas around the spots
ultimately give the entire plant a yellowed appearance (Fig. 5,
Rooting Failure.-Celery is seeded on top of the beds, and the
seed are not covered. Frequently, the young radicle grows hori-
zontally rather than vertically. When the tip does come in con-
tact with the soil, it may be "burned off". Either lateral roots
are formed, anchoring the plant, or the seedling dies. This re-
sults in stunted plants and poor stands.

The causal relations of early blight, late blight and bacterial
blight are established. A recent report has been made on the
new anthracnose (3). There appears to be an area of uncer-
tainty, however, concerning the etiology of the other diseases.
In 1924 Foster and Weber (6) attributed damping-off of
celery seedlings to numerous fungi, including Pythium deBary-
anum Hesse, Sclerotinia sclerotiorium (Lib.) DBy, Fusarium
sp. and Rhizoctonia sp. Working in the Sanford area in 1940,
Brooks and Kelbert (5) recovered 47 isolates of Rhizoctonia and
51 of Fusarium sp. from 204 diseased celery seedlings. Later,
Townsend (10) stated that damping-off of celery in the Ever-
glades was due chiefly to Rhizoctonia solani Kuhn. In 1951 Tis-
dale et al. (8) stated that Fusarium, Pythium, and Rhizoctonia
were most consistently isolated from diseased root tips and stems
of celery seedlings grown in the Sanford area. Only recently,
Swank and Perry (7) attributed damping-off to R. solani and
Pythium sp.

10 Florida Agricultural Experiment Stations

The causative relations of red root are not clear. Foster and
Weber (6) could not attribute red root to any specific organism
or condition, but believed it was caused often by injuries from
fertilizer burns, through which secondary fungi, such as Fusa-
rium sp., later enter. They also postulated that extremely
acid soils might be responsible. Townsend and Felix (11) were
unable to determine the etiology of brown root rot in the Ever-
glades; whereas, Swank and Perry (7) associated R. solani,
Pythium sp. and Fusarium sp. with red root in Sanford. It has
been postulated (2) that ectoparasitic nematodes may play a
role in this complex problem.
In summary, it appears that concepts regarding the etiology
of certain celery diseases in south Florida have evolved through
the years with only limited data as a basis.
Isolations and Greenhouse Pathogenicity Trials.-Samples of
diseased seedlings of both the golden and the pascal varieties
were collected periodically throughout the growing seasons of
1954-55 and 1955-56. Separate records were kept of isolations
from roots and stems. Two procedures were followed-one
where no surface sterilant was used, the other where the pieces
were soaked in 20 percent Clorox for three minutes immediately
before plating onto potato-dextrose or corn-meal agar.
R. solani was by far the dominant fungus isolated from dis-
eased seedlings taken from the margin of the circular spots of
dead plants. Isolates of this fungus were highly pathogenic on
celery seedlings in the greenhouse. They caused early post-
emergence damping-off on young seedlings. On older seedlings,
petioles were attacked, producing the aerial damping-off effect
described above (Fig. 3). In addition, a stem decay developed
at the soil level.
Quite different results were obtained in the case of damped-
off seedlings that occurred in an indefinite pattern, and from
plants showing yellows and red root symptoms and a soft wa-
tery rot of the entire stem (Table 1). Of 619 roots of Golden
Supreme and summer pascal varieties showing red root symp-
toms, R. solani was recovered from only two, whereas, 271 iso-
lates of Fusarium sp. were recovered and 37 of Pythium sp.
The last named was not once recovered from rootlets where a
surface sterilant was used. The sensitivity of Pythium to sur-
face sterilants has been noted before (4).
Fusarium sp. was also the dominant fungus isolated from
the stems of plants showing leaf yellows. Pythium sp. was re-


IFungi Isolated

Plant Symptoms Disinfectant No. Golden SupremeNo. Summer Pascal
Part Pieces Fusa- Rhizoc- Pieces Fusa- Rhizoc-
Plated rium Pythium tonia Plated rium Pythium tonia -o

Root Red root None 215 104 12 0 189 92 25 1 o
and damp-
ing-off Clorox 100 39 0 0 115 36 0 1

Total 315 143 12 0 304 128 25 2

Stem Yellows None 130 42 25 7 230 87 4 2

Clorox 122 60 8 0 45 15 0 3

Total 252 102 33 7 275 102 4 5

Grand Total .................... ......... ......... 567 245 45 7 579 230 29 7

lamping-off was of the early post-emergence type.


12 Florida Agricultural Experiment Stations

covered much less frequently, while Rhizoctonia was only rarely
isolated (Table 1).
In greenhouse pathogenicity trials, isolates of Fusarium
caused red root, vascular discoloration, yellowing and death of
the plants. Pythium isolates caused a watery root rot and stem
rot, as frequently observed in the field, but did not cause typical
red root.
It is concluded from these data that R. solani is the causal
agent of late post-emergence damping-off of celery. Of the fungi
isolated, Fusarium is the dominant one involved in the red root
and yellows diseases. Pythium is of much less importance and
R. solani is very minor, if involved at all. The possibility of
other causative factors cannot be ruled out, since better than
50 percent of the plant parts plated out did not yield pathogenic
fungi. In several instances platings of red root material, that
had been washed only in tap water with no surface sterilant
used, yielded no growth on agar media. As a result of these and
other observations, it is suggested that ectoparasitic nematodes
may be involved in the etiology (2). Certainly, the red root
symptoms would not preclude this possibility. Pythium sp. (p)
is the primary agent involved in a certain type of early post-
emergence damping-off, characterized by a soft stem rot.
Identification.-All the Rhizoctonia isolates fitted the de-
scription of R. solani Kuhn and are considered typical represen-
tatives of that species. The Fusarium isolates were of the F.
oxysporum group 2 and are classified as F. oxysporum f. apii.
No attempt was made to determine the species of Pythium.

Due to their intensified culture, and to the fact that much of
the seedbed period occurs during the rainy season, the produc-
tion of disease-free seedlings has been a major problem in the
Everglades. Indeed, celery could not be grown in the Everglades
at all were it not such a hardy crop.
There are at least four major diseases of celery in the seed-
bed, and three of lesser importance. The four important ones
are damping-off, early blight, bacterial blight and red root.
The three lesser diseases are late blight, Fusarium yellows and
anthracnose. Any or all of these diseases may appear simul-
taneously in a seedbed. Proper field diagnosis, therefore, is diffi-
2 The writer is indebted to Dr. W. C. Snyder, University of California,
Berkeley, California, for confirmation of the identity.

Etiology and Control of Celery Diseases in the Everglades 13

cult to impossible. In fact, detailed laboratory and greenhouse
pathogenicity studies frequently are necessary to supplement
field diagnosis. Such procedure, as routine operation by the
grower, is not possible. The logical approach to this problem,
therefore, appears to be to develop an effective control for each of
the important diseases singly, then to employ a combination of
materials in a protective program against all of them. This
would have the desirable feature of obviating the necessity of
positive diagnosis. Such a program necessarily would involve
soil treatment for the root and vascular diseases and foliar sprays
for the leaf diseases.
Work has been underway for several years in Florida on
control of celery seedbed diseases. In 1944 Townsend (10) re-
ported on several years' work. He found that seed treatments
were ineffective for the control of damping-off. The fumigants,
formaldehyde and chloropicrin, provided a degree of control for
this disease, but apparently were not completely satisfactory.
He observed that use of these materials resulted in growth stim-
ulation. Neither material has been used on celery seedbeds in
the Everglades since Townsend's report. Townsend also tried
several particulate materials-none of which showed any par-
ticular promise as pre-seeding soil treatments, and several were
phytotoxic. Materials tested included ceresan (5 percent ethyl
mercury phosphate), yellow cuprocide, basic copper sulfate, chlor-
anil, ferbam and thiram. Both ferbam and thiram gave effective
control of Rhizoctonia damping-off when applied as a plant spray
(1/2 pound/50 gals., 15 gals./1200 sq. ft.), but prevented proper
rooting of the seedlings. Chlorapiil also proved highly effective,
but injury resulted when used at 2 lbs./50 gals. He suggested
using 11/2 lbs./50 for the first three sprays. Yellow cuprocide
(3/ lb./50) also effectively controlled damping-off, but caused
a slight stunting of small seedlings. Ceresan controlled damp-
ing-off, but was injurious when used over the entire season.
In 1946 Townsend and Felix (12) found that yellowing and
stunting of plants due to brown root rot (red root?) did not oc-
cur where ammonium thiocyanate had been applied at 1000
lb./A. Sulfur and formaldehyde appeared to have little or no
In 1952 Tisdale, Moore and Swank (8) reported that drench-
ing sandy soils in the Sanford area with Spergon (chloranil),
Z.A.C. (Ziram) and Tersan (thiram) caused no reduction in red
root. Some of the particulate materials did have value, how-

14 Florida Agricultural Experiment Stations

ever, when mixed with the soil. These, in order of effective-
ness, were: Arasan SF (thiram), Robertson Copper Fungicide,
chloranil and Mathieson 290. Fumigants for control of damp-
ing-off and red root in descending order were as follows: methyl
bromide, trans 1-4 dibromo butane 2, chloropicrin, and dichloro-
propene-dichloropropane. The present work, covering the pe-
riod 1954-57, was divided into two phases, 1) soil treatment and
2) foliar sprays.
Soil Treatment.-Five tests were carried out on two farms
near Belle Glade. The seedbed site of one was known to be
heavily infested with the Fusarium yellows organism; the other
with root knot nematode. Damping-off and red root were com-
mon at both locations. The work was divided into two phases-
one employing soil fumigants, the other, particulate materials
used as drenches in water suspension, or applied in dry form and
worked into the upper three to four inches of soil.
Commercial seedbeds are of a standard size (300' x 4'). In
all the seedbed work, plots were 10 feet long. Thus, each plot
consisted of 40 sq. ft. Each test comprised four replications in
randomized blocks. Pertinent information relative to the appli-
cation of the soil fumigants appears in Table 2, and for the
particulate materials, in Table 4. Unless otherwise indicated,
all indexes (stand, disease severity, root vigor, leaf vigor) are
on a 0-11 basis where a score of 11 represents the maximum
Similar results were obtained from all five tests. Results are
summarized in Table 3.
The superiority of methyl bromide and chloropicrin is at
once apparent. The high level of chloropicrin was more effective
than the low. Formaldehyde was next in order of effectiveness,
equalling methyl bromide and chloropicrin in control of Fusarium
yellows and Pythium damping-off. The failure of formaldehyde
to control adequately red root, as noted previously (12), and the
ultimately low root and leaf vigor ratings are of particular inter-
est. The plots treated with formaldehyde were equal to the
methyl bromide and chloropicrin plots from the standpoints of
both plant vigor and freedom of roots from disease until Septem-
ber 10 (Fig. 6, upper). Following that time, however, plant
growth practically ceased (Fig. 6, lower) and red root built up
rather rapidly in the formaldehyde-treated plots. Isolations
from these diseased roots were negative. This, together with

Etiology and Control of Celery Diseases in the Everglades 15


tration in Rate of Method of
Treatment* 100 Gals. Application Application Seal
IWater _

Methyl bromide 1 lb./40 sq. ft. gas Poly-
Chloropicrin 2 gal./1000 sq. ft. hand injector water
Chloropicrin 1 gal./1000 sq. ft. hand injector water t
Formaldehyde 4 gal. 2 qt./sq. ft. drench none
Formaldehyde 4 gal. 1 qt./sq. ft. drench none
Vapam 2260 ml** 1 qt./sq. ft. drench none
Shell CBP
Emulsifiable 3 gal. 1 gal./sq. yd. drench water t

The active ingredient of Shell CBP is chlorobromo propene; of Vapam, N-methyl
** Equivalent to 300 lbs. active ingredient/acre.
t Sealed at rate of 1 gal./sq. yd.


Fusa- Pythium Red lart Root Leaf J Final
Treatment** rium Damp- Root Discol- Vigor Vigor I Stand
Yellows ing-off oration I

Check ................ 6.0 5.5 7.5 75 5.0 2.5 1.5

Methyl bromide 1.0 1.0 1.5 18 11.0 11.0 11.0

Chloropicrin .... 1.0 1.0 1.0 22 11.0 11.0 11.0

Chloropicrin .... 1.0 1.0 2.5 40 10.5 11.0 9.5

Formaldehyde .. 1.0 1.0 3.5 36 9.0 8.5 11.0

Formaldehyde .. 1.0 1.0 5.5 24 6.5 6.5 11.0

Vapam ............. 4.5 4.0 3.5 38 7.5 7.0 8.0
Shell CBP ........ 4.0 4.0 6.0 46 6.5 5.5 7.0

All indexes on a 0-11 basis where 11 equals maximum rating.
** See Table 2 for concentration of materials and methods of application.
t Percentage of plants out of 25 sampled from each replication showing vascular dis-
coloration of the stem.
The leaf (blade and petiole) comprises the major portion of the above-ground portion
of the plant. Thus. leaf vigor is synonymous with plant vigor.

16 Florida Agricultural Experiment Stations

the fact that formaldehyde is known to be an ineffective nemta-
cide, suggested that red root as manifested in these plots might
be due to ectoparasitic nematodes (see above). Vapam and Shell
CBP were less effective than the other materials under all cate-
gories listed in Table 3. All materials tested showed some weed
control (not shown in Table 3). Methyl bromide was most
In another test, involving an area known to be infested with
the root knot nematode, methyl bromide provided superior con-
trol of root knot, and chloropicrin and Vapam were almost as
good. In this test, Vapam controlled red root as effectively as
chloropicrin; methyl bromide provided somewhat better control.
Confining chloropicrin fumes with polyethylene sheeting pro-
vided no particular advantage over that of a water seal.

Fig. 6.-Root development of celery seedlings from plots treated as
follows: Upper, 1. to r.: Methyl bromide, formaldehyde, chloropicrin,
check-on September 16, 1954. Lower, 1. to r.: Check, chloropicrin, for-
maldehyde, methyl bromide-on October 1, 1954, from the same plots.
Note above that root development from plots treated with formaldehyde
is almost equal to that from plots treated with methyl bromide and chloro-
picrin, but two weeks later root development in the formaldehyde plots was
much inferior to that of the other two.


V N7

j 't

BI 4

Etiology and Control of Celery Diseases in the Everglades 17

The value of soil fumigation with chloropicrin on a commer-
cial scale, in an area heavily infested with the root knot nema-
tode, is illustrated in Figure 7.
Materials used in the pre-seeding soil treatments involving
particulate fungicides and results are summarized in Table 4.
When viewed from the standpoints of both final stand and dis-
ease control, only Crag 974 showed any particular promise. Di-
thane M-22 mixed in the soil as a powder showed a degree of
control, but was phytotoxic. Orthocide and Fermate reduced
stands by preventing proper rooting of the seedlings.
It is interesting to note that fungicidal action was better
when the materials were mixed in powder form in the upper four
inches of soil; whereas, phytocidal activity, as illustrated by
reduced stands, was considerably higher when toxic materials
were applied in water suspension. Obviously, better distribu-
tion was obtained when the materials were mixed in the soil
in dry form. This resulted in more fungicidal activity. In the

Fig. 7.-Effect of soil fumigation with chloropicrin in an area heavily
infested with root knot nematode on stand of celery seedlings. The bed
with the poor stand received no fumigant; the others received fumigant at
the rate of 2 gallons to the bed.

18 Florida Agricultural Experiment Stations

case of the drench, the muck soil no doubt acted as a sieve, filter-
ing out the particulate material from the suspension at or near
the soil surface. Since seeding is accomplished on the soil sur-
face, the young radicle of the germinating seedling would come
in direct contact with the concentrated material, thereby en-
hancing phytocidal action.

I Fusa-
How rium
Materials** Concentration Rate Ap- Stand Yellows
pliedt & Damp-

Check ........... -- 3.0 7.0
Crag Fungi-
cide 531 .... 165 gms./4% gal. 400 lbs./A. Drench 5.5 6.0
Crag Fungi- Powder
cide 531 .... 400 lbs./A. mixed 4.0 5.5
Crag Fungi-
cide 974 .... 123.6 gms./4' gal. 300 1bs./A. Drench 6.0 5.5
Crag Fungi- Powder
cide 974 .... 300 lbs./A. mixed 10.0 3.0
Dithane D-14 1 gal. 100 2 gal./sq. yd. Drench 4.0 5.5
Orthocide ...... 165 gms./4% gal. 400 1bs./A. Drench 3.0 6.0
Orthocide ...... -400 lbs./A. mixed 4.5 5.5
Dithane Z-78 165 gms./4'/ gal. 400 lbs./A. Drench 6.0 5.0
Dithane Z-78 400 lbs./A. mixed 7.5 6.5
PCNB ............ 165 gms./4Y2 gal. 4001bs./A. Drench 5.0 7.0
PCNB ............ -400 lbs./A. mixed 6.0 5.5
Fermate ....... 165 gms./4% gal. 400 lbs./A. Drench 2.0 8.0
Fermate ........ 400 lbs./A. mixed 3.5 7.0
Dithane M-22 1 123.6 gms./4 gal. 300 lbs./A. Drench 2.5 6.0
Dithane M-22 I 300 lbs./A. mixed 7.5 3.5

All indexes on a 0-11 basis where 11 equals maximum rating.
** Active ingredient and percentage composition of materials listed as follows: Crag
Turf Fungicide 531, a copper-chromate-zinc complex; Crag Fungicide 974 (now known as
Mylone), 90 percent 3-5-dimethyl-tetrahydro-l,3-5,2H thiadiazine-2-thione; Dithane D-14, 19
percent nabam; Orthocide, 50 percent captain; Dithane Z-78, 65 percent zineb; PCNB, 50
percent pentachloronitrobenzene; Fermate, 76 percent ferbam; Dithane M-22, 70 percent
t Dry powders were raked into the upper 4 inches of soil.
Damping-off was of early post-emergence type caused by Fusarium oxysporum f. apii
and Pythium sp. (p).

None of the pre-seeding soil treatments, fumigants or partic-
ulate materials provided lasting protection against late damping-
off. This is not surprising in view of the many opportunities
for re-contamination of the beds during their three-month period.

Etiology and Control of Celery Diseases in the Everglades 19

Thus, it was obvious that soil fumigation would have to be sup-
plemented with soil drenches or foliar sprays.
In other experiments, several fungicides were applied as post-
emergence drench treatments at the rate of one-half gallon of
suspension to the square yard of bed. The first application was
made one week after seeding, as the seed were germinating, and
subsequent ones at weekly intervals. Chloranil (Spergon),
PCNB, ferbam (Fermate), dichlone (Phygon) and the neutral
coppers provided effective control of late damping-off (R. solani).
Zineb (Dithane Z-78) and Captan (Orthocide) were less effective.
Ferbam, chloranil and PCNB caused temporary stunting of the
young seedlings, but the plants completely recovered by the
fourth week.
Captan caused severe injury which resulted in greatly re-
duced stands (Fig. 8). Initial injury showed within 48 hours
after treating the plots; the seedlings remained prostrate, i.e.,
the radicles did not bend down. Also, the hypocotyl frequently

Fig. 8.-Effect of Captan on stand when applied to
very young celery seedlings.

20 Florida Agricultural Experiment Stations

showed a curvature. As lateral roots were formed, they were
"burned off" as they came in contact with the soil surface. It
was concluded that this was due to injury from Orthocide. In
subsequent work injury by Orthocide was found to occur only
when it was applied to the seedbed during the first four weeks
after seeding.
Dichlone also caused severe injury. Fortunately, this ma-
terial is not used by celery growers.
Foliar Sprays.-Since soil treatments were only effective
against root diseases, foliar spray tests were also undertaken.
This work was done concurrently with the soil treatment tests
and included 10 separate trials.
Post-emergence damping-off generally is considered a soil
problem, and control is directed toward treating the soil. As
shown under "Symptomatology" and in Figure 3, however, damp-
ing-off symptoms occur on petioles well above soil level. This
suggested that instead of drenching the beds at the rate of 1/
gallon to the square yard (over 65 gals. to the bed), a more con-
ventional foliar spray might be adequate. This would have sev-
eral advantages: 1) applications with a conventional spray rig
would be possible; 2) it would also make possible combining the
control operations for damping-off and for the leaf blight dis-
eases; 3) the likelihood of phytotoxicity should be lessened be-
cause of reduced gallonage output (10 gals./bed instead of 65).
Using this procedure, it was found that any number of ma-
terials provided adequate control of damping-off. These in-
cluded Spergon (chloranil) (4/100), Fermate (ferbam) (2/100),
any of the neutral coppers (2 lbs. metallic copper/100) and PCNB
(2/100). Dithane M-22 (maneb) (11/100), though less effec-
tive, also showed a significant degree of control.
During this work effective control of bacterial blight was
developed (1). The neutral coppers and streptomycin used alone
and in mixture were effective. Information on control of early
blight has long been available (10). Thus, the stage was set for
the testing of combination sprays involving effective materials
against damping-off, early blight and bacterial blight. Several
such tests were run. Results are summarized in Table 5.
All combinations provided a high degree of control of bac-
terial blight and early blight, as well as damping-off. None of
the mixtures was completely incompatible, although chloranil-
zineb-Agrimycin-100 and CopperA-zineb-Agrimycin-100 caused
a bronzing of the leaves. It was also found that Agrimycin-100

Etiology and Control of Celery Diseases in the Everglades 21

at concentrations of 100 ppm or higher caused a leaf chlorosis
(not shown in Table 5). In the greenhouse this injury was
noticeable at much lower concentrations (Fig. 9).


Treatments* (lbs./100 gals. Damping- Bacterial Early
and ppm) off** Blight** Blight**

Check ............. 6.0 5.2 4.7
S P A.... 4-2-50 0.7 0 0
TBCS P A 4-2-50 1.2 0 0
C P A ........ 4-2-50 1.5 0 0
F P A ... ... 4-2-50 1.2 0 0
0 P A ....... 4-2-50 1.5 0 0
PCNB P A 4-2-50 1.0 0 0

S = Spergon
P = Parzate (65 percent zineb)
A = Agrimycin-100 (15 percent
streptomycin sulfate, 1.5
percent oxytetracycline)
TBCS = Tribasic copper sulfate
C = Copper A
F = Fermate (76 percent ferbam)
O = Orthocide (50 percent captain)
PCNB = Pentachloronitrobenzene
** All indexes on a 0-11 basis where 11 equals maximum rating.

A test was run under severe conditions in September, 1956,
where four diseases (Rhizoctonia damping-off, early blight, bac-
terial blight and anthracnose) were involved. During this work
it was necessary to spray three times weekly to hold all these
diseases in check. Results are shown in Table 6.
None of the materials, used singly, controlled all the diseases,
nor did any two. A high degree of control was obtained with

Fig. 9.-Chlorosis caused by Agrimycin on greenhouse-grown celery
seedlings. Left to right: 50, 20 and 0 parts per million.


22 Florida Agricultural Experiment Stations


1 Rhizoc-
Concentration tonia** Early** Bacte- Anthrac-
Treatments* (lbs./100 gals. Damp- Blight rial** nose**
___or ppm) ing-off Blight

Check ...................- 8.0 4.5 3.5 4.5
Agrimycin-100 ...... 100 ppm 7.9 4.0 0.0 3.8
DO. ................. 50 ppm 7.9 4.0 0.5 4.5
DO. ................-. 25 ppm 8.0 4.5 0.7 4.7
TBCS ...................... 4 lbs. 2.0 4.2 1.0 1.0
Spergon .................. 4 lbs. 1.0 0.8 3.2 3.2
Thylate ..............-... 1% lbs. 0.0 0.2 3.5 4.0
TBCS-Agrimycin.. 4 lbs.-25 ppm 2.0 2.9 0.0 1.0
Agrimycin-100 ...... 4 lbs.-25 ppm 0.5 1.0 1.0 3.0
Agrimycin-100 ...... 11 lbs.-25 ppm 0.0 0.2 0.7 3.8
Agrimycin-100 ...... 2 lbs.-25 ppm 2.2 0.0 1.0 2.8

TBCS-Parzate- 4 lbs.-2 lbs.
Agrimycin-100 ...... 25 ppm 1.0 0.0 0.7 0.0
Spergon-Parzate- 4 lbs.-2 lbs.
Agrimycin-100 ...... 25 ppm 0.0 0.0 0.1 2.0
Thylate-Parzate- 1 % lbs.-2 lbs.
Agrimycin-100...... 25 ppm 0.0 0.0 0.5 0.2

Active ingredient and percent composition of materials not previously shown: Thylate,
65 percent thiram.
** All indexes on a 0-11 basis where 11 equals maximum rating.

Fig. 10.-Effect of combination sprays on stand of celery seedlings in
the seedbed. Above; Sprayed with a mixture of thiram, zineb and Agrimy-
cin. Lower: Unsprayed check. Stand in the check plot is approximately
50 percent of that in the sprayed plot.

-'CA,. -.

Etiology and Control of Celery Diseases in the Everglades 23

mixtures of tribasic copper sulfate-zineb-Agrimycin-100, chlora-
nil-zineb-Agrimycin-100 or thiram-(Thylate) -zineb-Agrimycin-
100. The first two mixtures caused a leaf injury when applied
during hot weather. The thiram-zineb-Agrimycin-100 mixture
did not cause injury and provided excellent control of all the dis-
eases (Fig. 10). This mixture appeared to be especially prom-
ising. In view of the possible injury to young seedlings, it is not
advisable to employ any of the combinations until the covers are
removed, approximately six weeks after seeding. During the
first six weeks a "straight copper" program is the safest and
most effective.

One of the worst epiphytotics of early blight in the history of
the Everglades occurred during the spring of 1957. Hundreds
of acres were abandoned and yield from the remaining was re-
duced greatly. During this period two experiments were run
comparing several materials alone and in combination against
early blight. A summer pascal type celery was used in both
tests. Experimental design consisted of single 50-foot-row plots
replicated four times. Each plot row was bounded on either
side by an unsprayed guard. Depending on the weather, ma-
terials were applied at three to five-day intervals. Nozzle num-
ber to the row increased from two, when the celery was young,
to a maximum of six as it approached harvest. Corresponding
gallonage to the acre range was 56 to 167. Twenty-one sprays
were applied during the first test; 20 during the second. For
the first test transplants were set February 5 and harvested
May 13. Corresponding dates for the second test were February
19 and May 21. Disease indexes were scored visually on a 0-11
basis, where 11 equalled maximum severity.
Test No. 1.-Results of this test are shown in Table 7. The
most interesting observation is the outstanding performance of
Dyrene from the standpoint of control of early blight. Another
was the rather poor performance of zineb (Parzate) at the rec-
ommended dosage of 2 lbs./100 gals. Maneb (Manzate) at the
recommended dosage was also significantly less effective than
Dyrene. Tribasic copper sulfate provided a surprising degree
of control, while thiram (Thylate) was intermediate in effective-
ness. The Actidione formulations were virtually ineffective.

24 Florida Agricultural Experiment Stations


tration Early Blight Severity** Rhizoc- Yield
Materials* (lbs./100 tonia** (no.
gals. or I 5 Stalk stalks)
_ppm) 4/22 5/1 5/7 5/13 Rot

Check ............ 6.0 7.0 6.8 9.0 8.0 0
Parzate ........ 2 lbs. 1.6 3.3 3.8 4.3 6.0 36
Parzate ........ 3 lbs. 1.5 2.8 2.8 2.5 4.0 58
Thylate -....... 1 lbs. 3.5 4.5 4.3 5.0 1.0 73
Thylate ........ 2 lbs. 3.8 4.8 4.5 4.5 1.0 78
TBCS ........... 4 lbs. 3.0 4.0 3.3 3.3 1.5 79
Parzate + 1 lb.-
Thylate ...... 1 lb. 2.1 3.3 3.1 2.3 1.0 76
Parzate + 2 lbs.-
Thylate ....... I 1%1 lbs. 1.1 2.5 2.5 2.0 1.0 83
Dyrene .......... 2 lbs. 0.9 1.3 1.5 1.5 2.0 76
Manzate ........ 1% lbs. 1.5 3.3 3.5 3.0 2.0 77
Manzate + 1 lb.-
Thylate ....- I 1 lb. 1.5 2.8 3.0 2.8 1.0 82
Manzate + 1% lbs.-
Thylate ....... bs. 1.0 2.4 3.0 2.9 1.0 77
TBCS + 3 lbs.-
Parzate ........ 1 lbs. 1.9 3.3 3.3 2.5 2.0 81
Actidione A .- 25 ppm I 3.8 5.8 5.8 8.0 8.0 0
Actidione T .. 25 ppm 4.0 5.3 5.3 7.0 8.0 0
L.S.D. .05 .. 0.8 0.9 0.8 1.4 1.0 13
.01.... 1.1 1.0 1.0 1.8 1.4 19

Active ingredient and percent composition of materials not previously shown: Dyrene,
50 percent 2,4-Dichloro-6-(0-ehloroanilino) Triazine.
"** All indexes on a 0-11 basis where 11 equals maximum rating.

Another point of interest was the effect of mixtures of thiram-
zineb and thiram-maneb. Better control of early blight was ob-
tained with the thiram-zineb mixture using one pound of each
material, than with zineb at three pounds. This tends to con-
firm the previous report of synergism between these two mate-
rials (3). The thiram-maneb mixtures showed definite additive
effects, but there was no strong evidence of synergism.

Etiology and Control of Celery Diseases in the Everglades 25

A final observation was the effect of these materials on Rhizoc-
tonia stalk rot. Effects of this disease had a direct bearing on
yield. Although thiram provided only intermediate control of
early blight, its control of Rhizoctonia stalk rot was excellent.
Zineb gave better control of early blight, but poor control of stalk
rot. Other materials providing significant degrees of control of
stalk rot were tribasic copper sulfate, Dyrene and maneb.
Test No. 2.-Results of this test are shown in Table 8. The
most striking observation was the superior performance of tri-
basic copper sulfate-Dyrene mixture from the standpoint of con-
trol of early blight and Rhizoctonia stalk rot (Figs. 1 and 11).
Also, nabam (Parzate liquid) plus zinc sulfate was more effec-
tive than zineb (Parzate powder).

1 Concen- Rhizoc- I
traction Early Blight Severity** tonia** Yield
Treatments* (lbs./100 1 ( Stalk Wt.
or ppm) 5/1 5/7 5/14 5/20 Rot No. (lbs.)

Check ............ 6.0 6.8 9.0 10.0 9.0 0 0
(zineb) ........ 2 Ibs. 2.0 2.5 4.0 3.5 7.0 46 68
(nabam)- 2 qts.-
zinc sulfate.. % lb. 1.0 1.8 2.5 2.5 4.0 80 99
Phaltan ........ 3 lbs. 2.0 3.3 4.5 4.0 3.5 78 87
Amtbam ........ 2 qts. 5.3 6.0 9.0 10.0 9.0 0 0
Manzate ........ 1 lbs. 1.3 3.3 4.5 3.5 3.5 73 80
Zerlate ........ 2 lbs. 3.0 3.3 4.3 4.3 4.0 83 96
Fermate ........ 3 lbs. 3.5 4.0 5.5 5.5 2.5 78 88
Dyrene .......... 2 lbs. 1.0 2.3 3.8 2.8 2.5 82 104
TBCS ......... 4 lbs. 3.3 3.8 4.0 3.5 2.5 83 91
TBCS- 3 lbs.-
Parzate ........ 1% lbs. 2.5 2.3 3.0 2.3 3.0 82 97
TBCS- 3 lbs.-
Dyrene .......... 1% lbs. 1.0 1.0 1.3 1.0 1.0 83 107
100 .............. 50 ppm 6.3 6.3 9.0 10.0 9.0 0 0
100 .............. 100 ppm 6.8 6.3 8.8 10.0 9.0 0 0
Zerlate- 1 lb.-
Fermate ...... 2 bs. 3.5 3.5 4.8 4.8 2.0 83 91
L.S.D. .05....
.01.... 0.6 1.0 0.7 0.9 1.0 7 16
0.8 1.3 1.0 1.2 1.3 9 22

Active ingredient and percent composition of materials not previously shown; Phaltan,
50 percent N-trichloro-methylthiophthalimide; Amtbam, 20 percent ammonium tetraethylene-
amine bisdithiocarbamate.
** All indexes on a 0-11 basis where 11 equals maximum severity.

Results of these two field tests clearly indicate that the rec-
ommended spray program for celery in the Everglades should

26 Florida Agricultural Experiment Stations

be revised. In the first place, zineb and nabam plus zinc sulfate
should not be used alone, because of their failure to control either
or both early blight and Rhizoctonia stalk rot. Dyrene should
be included, chiefly because of its effectiveness against early
blight. Thiram should be included because of its effectiveness
against stalk rot and its additive or possibly synergistic effect
on zineb and maneb. Certain mixtures show particular prom-
ise; these include Dyrene-neutral copper, thiram-zineb and thi-
The celery industry of the Everglades is confronted with sev-
eral important diseases including those initiating below the soil
level (red root, root knot and Fusarium yellows), as well as sev-
eral above-ground (damping-off, early blight, bacterial blight,
late blight and anthracnose). Supplementary information on the
symptomatology and etiology of the diseases is presented. Fusa-
rium oxysporum f. apii was the fungus most frequently associ-
ated with early post-emergence damping-off, red root and yel-
lows, and this fungus produced symptoms characteristic of these
diseases on celery under greenhouse conditions. Pythium sp. (p)
was associated much less frequently with these diseases. In
the greenhouse isolates of Pythium produced more of a soft
watery rot (damping-off) than red root or yellows-type symp-
toms. The possibility of ectoparasitic nematodes playing a role
in the etiology of red root is suggested. Rhizoctonia solani was
the dominant organism associated with late post-emergence
In the seedbed methyl bromide and chloropicrin consistently
gave better control of red root, root knot and yellows than other
fumigants or particulate materials tested. Formaldehyde gave
good control of yellows, but failed to control red root. None of
these provided adequate control of Rhizoctonia damping-off, but
several particulate materials as foliar sprays did. These in-
cluded chloranil, ferbam, PCNB, the neutral coppers and thiram.
In the seedbed zineb or maneb provided the most effective
protection against early blight; the neutral coppers or strepto-
mycin against bacterial blight; and the neutral coppers or a
mixture of zineb and thiram against anthracnose.
Mixtures of chloranil-zineb-streptomycin, neutral copper-zi-
neb-streptomycin or thiram-zineb-streptomycin were highly ef-
fective against all the foliar diseases in the seedbed (damping-
off, early blight, bacterial blight and anthracnose). The first

Etiology and Control of Celery Diseases in the Everglades 27

two mixtures caused light to moderate plant injury under cer-
tain conditions.
Under field conditions Dyrene showed particular promise
against early blight. Thiram was most effective against Rhizoc-
tonia stalk rot. Zineb was intermediate against early blight and
inferior against Rhizoctonia stalk rot. Maneb, though better
than zineb, also failed to provide maximum protection against
either disease.
Several mixtures looked promising. Zineb and thiram in mix-
ture appeared to be synergistic in their action against early
blight. Maneb plus thiram also was effective. Tribasic copper
sulfate plus Dyrene were particularly outstanding against early
blight. All these mixtures were also quite effective against
Rhizoctonia stalk rot.


1. Cox, R. S. Compatibility between a streptomycin-terramycin formula-
tion and copper in the control of bacterial blight of celery. Plant
Dis. Reptr. 39: 484-486. 1955.
2. Cox, R. S. Control of diseases in the celery seedbed. Proc. Fla. St.
Hort. Soc. 69: 242-244. 1955.
3. Cox, R. S. Anthracnose, an undescribed disease of celery in the Ever-
glades. Plant Dis. Reptr. 41: 790-793. 1957.
4. ELLIS, D. E., and R. S. Cox. The etiology and control of lettuce damp-
ing-off. N. C. Agr. Exp. Sta. Tech. Bul. 94. 1951.
5. BIooKS, A. N., and D. G. A. KELBERT. Diseases of celery other than
early blight and pink rot. Fla. Agr. Exp. Sta. Ann. Rpt. 1940:
6. FOSTER, A. C., and G. F. WEBER. Celery diseases in Florida. Fla. Agr.
Exp. Sta. Bul. 173. 1924.
7. SWANK, GEORGE, JR., and V. G. PERRY. Control of diseases in the celery
seedbeds with methyl bromide. Fla. Agr. Exp. Sta. Cir. S-55.
8. TISDALE, W. B., W. D. MOORE and GEORGE SWANK, JR. Damping-off
and root rots of vegetable crops. Fla. Agr. Exp. Sta. Ann. Rept.
1951: 94.
9. TISDALE, W. B., W. D. MOORE and GEORGE SWANK, JR. Damping-off
and root rots of vegetable crops. Fla. Agr. Exp. Sta. Ann. Rept.
1952: 112-113.
10. TOWNSEND, G. R. Controlling damping-off and other losses in celery
seedbeds. Fla. Agr. Exp. Sta. Bul. 397. 1944.
11. TOWNSEND, G. R., and E. L. FELIX. Diseases of celery other than early
blight and pink rot. Fla. Agr. Exp. Sta. Ann. Rept. 1945: 212-213.
12. TOWNSEND, G. R., and E. L. FELIX. Diseases of celery other than early
blight and pink rot. Fla. Agr. Exp. Sta. Ann. Rept. 1946: 186.

Fig. 11.-Plants from plots sprayed with: left, Dyrene plus tribasic cop-
per sulfate; center, unsprayed check; right, nabam plus zinc sulfate. Note
the cleanliness and size of stalk that was sprayed with Dyrene plus copper.
The small size of the unsprayed plant is due to the combined action of early
blight and Rhizoctonia stalk rot; lesions of the latter occur at the base and
along the sides of the petioles; the yellowed leaves are the result of early
blight lesions. The plant from the nabam-zinc sulfate plot is relatively free
of early blight but shows several Rhizoctonia lesions on the petioles.

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