Group Title: Ft. Pierce ARC research report
Title: Control of Pythium mrietylum [i.e. myriotylum] and P. arrhonomanes on tomato seedlings with fungicides added to plug-mix
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 Material Information
Title: Control of Pythium mrietylum i.e. myriotylum and P. arrhonomanes on tomato seedlings with fungicides added to plug-mix
Series Title: Ft. Pierce ARC research report
Alternate Title: Control of Pythium myriotylum and P. arrhonomanes on tomato seedlings with fungicides added to plug-mix
Physical Description: 3, 2 leaves : ; 28 cm.
Language: English
Creator: Sonoda, Ronald M
University of Florida -- Agricultural Research Center
Publisher: University of Florida, Institute of Food and Agricultural Sciences, Agricultural Research Center
Place of Publication: Fort Pierce
Publication Date: [1975]
 Subjects
Subject: Tomatoes -- Diseases and pests -- Control -- Florida   ( lcsh )
Fungicides -- Florida   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (leaf 3).
Statement of Responsibility: R.M. Sonoda.
General Note: Caption title.
General Note: "December 1975."
 Record Information
Bibliographic ID: UF00056045
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 02923936

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Ft. Pierce ARC Research Report RL-1975-6 Decee' a
nVrio0lum / ^/ ^
Control of Pythium--~e4ty"~ a and P. arrhenomanes on tomato
seedlings with fungicides added to plug-mix 1/ /

R. M. Sonoda "

ABSTRACT

Bay 22555, captain, chloroneb, Difolatan, or ETMT added to planting
good control of damp-off, lower stem rot, and root rot of tomatoes incited
Pythium myriotylum and P. arrhenomanes. Dithane M-45 and basic copper sulfate a
the rates used reduced disease severity but did not give adequate control. Difo-
latan at rates required for adequate control caused severe stunting of seedlings.
Both captain and chloroneb at rates adequate for control induced some symptoms of
phytotoxicity. Dithane M-45 was slightly pla1rtotoxic at the highest rate. The
highest rate of basic copper sulfate was not phytotoxic. Seedlings in plug-mix
with Bay 22555 and ETMT showed least signs of phytotoxicity at rates required for
control of the disease.


Control of Pythium myriotylum Drechs. and P. arrhenomanes Drechs. in plug-mix
plantings in virgin sandy soil in Florida has been achieved by incorporating ETMT
or Bay 22555 in the planting mix.(7). Neither of these compounds, however, are
registered for use on tomato. Captan, registered for other uses on tomato, was
only marginally effective in the field and reduced yields (7). Difolatan, Dithan-:
M-45, and basic copper sulfate, registered for other uses on tomato as well as
chloroneb, have been reported to be effective against P. aphanidermatum (Eds.)
Fitz. incited disease of tomato (2,5,6). The purpose of this paper is to report
tests comparing the efficacy of these compounds with ETMT, Bay 22555, and captain
against P. myriotylum and P. arrhenomanes incited tomato seedlings diseases.
Materials and Methods

Walter tomato seed, free of fungicide treatment, was mixed with planting mix
(Jiffy Mix Plus, a commercial 1:1 mixture of shredded sphagnum peat moss and
horticultural vermiculite similar to Cornell Peat-Lite Mix A (3) with 7-40-6
analysis Magamp added (4)) in a portable cement mixer at a rate equivalent to about.
five seed per two tablespoons of planting mix. The planting mix was divided into
lots and the following fungicides added to separate lots as aqueous suspensions:
1) basic copper sulfate; 2) captain (Orthocide) (N-((trichloromethyl)thio) 4 cyc-
lohexene-l,2-dicarboximide; 3) chloroneb (Demosan) (1,4-dichloro-2,5 dimethoxybea-
zene); 4) Bay 22555 (Dexon) (sodium-p-(dimethylaminobenzenediazosulfonate)); 5)
Difolatan (N-((1,1,2,2-tetrachloroethyl)sulfenyl)-cis-4-cyclohexene-l,2-dicarboxi.
mide; 6) Dithane M-45 (a coordination product of zinc ion and manganous ethylenebit


1/ The results presented in this report are only for information and do not con-
stitute nor imply recommendation of any fungicide for use in plug-mix planting
The mention of any trade name or proprietary product does not imply approval
of its use nor of its use to the exclusion of other products that may be suit-
able.

2/ Associate Plant Pathologist, University of Florida, Institute of Food and
Agricultural Sciences, Agricultural Research Center, Fort Pierce 33450







(dithiocarbamate); and 7) ETMT (terrazole) (5-ethoxy-3-thrichloromethyl-1,2,4-thia-
diazole).

Virgin- Oldsmar fine sand top-soil was air-dried, passed through a two mm mesh
wire screen and limed and fertilized with an equivalent of 1000 Ib per acre dolo-
mitic limestone and 600 Ib per acre of a 4-16-4 analysis fertilizer, respectively.
Isolates of P. myriotylum and P. arrhenomanes were obtained from diseased tomato
seedlings found in commercial fields. The isolates were grown on twice-autoclaved
Panicum fasciculatum seeds at room temperature for about two weeks then added to
soil. Six hundred g air dry weight infested soil was put into 16 oz styrofoam cups.
In Test'1, one isolate of P. arrhenomanes was added to the soil at a rate of about
120 infested P. fasciculatum seed per cup. In Test 2, four isolates of P. myrioty-
lum and one isolate of P. arrhenomanes were added to the soil at a rate of about 30
infested P. fasciculatum seeds each per cup.

The small end of a #7 rubber stopper was used to make a hole in the soil sur-
face in each cup. Two tablespoons of planting mix with or without fungicide were
placed in each of the cups and tamped down with the large end of the rubber stopper.
There were three control treatments in Test 1: a) infested soil with seed in plant-
ing mix without fungicide, b) infested soil with five seeds/cup pla=r:ti directly in
soil. There were two control treatments in Test 2: a) infested sol'. 71th seed in
planting mix without fungicide; and b) uninfested soil with seed in planting mix
without fungicide. The cups were taken into a field at the Agricultural Research
Center, Fort Pierce (ARC-FP), and buried upright leaving about 3/4 inch of the cup
exposed. There were ten cups per treatment in a randomized complete block design.
The plot areas were irrigated daily with one acre-inch of water using a Model #30
rainbird sprinkler except on days with sufficient rainfall. Test 1 was conducted
from mid-September to late September, Test 2 from early October to Mid-October.

The number of emerged seedlings and the number of damped-off seedlings were
recorded daily. Seedlings from both tests were pulled two weeks after planting and
the severity of root and lower stem necrosis rated. The rating system used, the
method of calculating a disease severity index, and the method of calculating a seed-
ling emergence index are shown on Tables 1 and 2. A rating of the qualitative ap-
pearance of the plants in Test 2 was made immediately before the plants were har-
vested. The rating system is shown on Table 2. All data was subjected to analysis
of variance and Duncan's Multiple Range Test was applied to the means.
Results and Discussion

Both damp-off and root and lower stem necrosis occurred with P. arrhenomanes
inoculum in Test 1. Most of the seeds placed directly in infested soil were appar-
ently killed before emergence (Table I). Several treatments were effective in re-
ducing disease severity (Table 1). The Difolatan treatments, although effective in
reducing disease, were phytotoxic. The symptoms of phytotoxicity were severe stunt-
ing of seedlings, reduced root growth, necrotic, tan lesions on the root surface,
and reduction in the rate of seedling emergence. Chloroneb, although reducing
disease severity at the highest rate used, had the fewest emerged seedlings of the
fungicide treatments. Previous tests (Sonoda, unpublished data) showed that higher
rates of chloroneb reduce the rate of tomato seedling emergence and reduced total
emergence. Captan, ETMT, and Bay 22555 gave good control of P. arrhenomanes with
no sign of phytotoxicity.

Damp-off and root and lower stem necrosis occurred with the combination of P.
myriotylum and P. arrhenomanes inoculum used in Test 2. Good control of the disease
was obtained with ETMT, Bay 22555, Difolatan and captain. Difolatan again






-3-

induced severe phyteteeity symptoms at rates required to give good control of dis-
ease. Captan induced moderate phytotoxic symptoms, including browning of root tips
and slower seedling growth. Seedlings grew slowly at higher rates of Bay 22555.
The appearance of seedlings in planting mix treated with ETMT did not differ sign-
ificantly from seedlings in the uninfested control treatment. Dithane M-45 and
basic copper sulfate at the concentrations used were ineffective in controlling
the disease as compared to the other fungicides. The highest rate of Dithane M-45
used reduced disease severity only slightly and retarded seedling emergence rate
the most.

The highest rate of basic copper sulfate used reduced disease severity slight-
ly as compared to the more effective fungicides but it did not delay the rate of
seedling emergence. Further tests with higher rates of this compound are warranted.
Alexander, however, reports phytotoxicity and poor control of tomato seedlingdamp-
off with monohydrated copper sulfate (l) innited.r by P. ul-imum.- Further work with
Difolatan to de+trminp ie 4ircre'is an effect on yield may also be warranted.
ErMT and Bay'22555 were superior to the other fungicides tested in efficacy
and safety to seedlings. Effective levels of these fungicides in plug-mix did
not reduce yields (7). Further work with these two compounds in order to obtain
approval for their use in plug-mix is being conducted at the ARC-FP.

Literature Cited

1) Alexander, L. J., H. C. Young, and C. M. Kiger. 1931. The causes and control
of damping-off of tomato seedlings. Ohio Ag. Expt. Sta. Bull. 496, 38pp.

2) Beach, W. S. and S. Y. Chen. 1942. Experimental control of damping-off in
tomato seedlings transplanted from sand, including immediate applications
of fungicidal drenches. Penn. St. Coll. Ag. Exp. Sta. Bull. 434, 26 pp.

3) Boodley, J. W. and R. Sheldrake, Jr. 1972. Cornell peat-lite mixes for com-
mercial plant growing. Information Bull. 43. N. Y. St. Coll. Ag. Cor-
nell Univ. 8 pp.

4) Hayslip, N. C. 1974. A "Plug-Mix" seeding method for field planting tomatoes
and other small-seeded crops. Ft. Pierce ARC Res. Rept. RL-1974-2.

5) Littrell, R. H., J. D. Gay, and H. D. Wells. 1969. Chloroneb fungicide for
control of Pythium aphanidermatum on several crop plants. Plant Dis.
Reptr. 53: 913-915.

6) Sonoda, R. M. 1972. Control of tomato transplant damp-off. Plant Dis. Reptr.
56: 840-842.

7) Sonoda, R. M. 1975. Incorporating fungicides in planting mix to control soil-
borne seedlings diseases of plug-mix seeded tomatoes. Plant Dis. Reptr.
(In press).















Table l, The effect of fungicides added to
arrhenomanes on seedling tomatoes
lings.


plug-mix on severity of Pythium
and emergence of tomato seed-


Sn Emergence Total
Fungicide Amount/ DSI-/ Indexc-.- Emerged
Difolatan 0.62 1.02 ad/ 6.2 f~l 47 abd/
Difolatan 1.25 1.14 a 6.1 ef 44 ab
Bay 22555 0.42 1.17 a 5.3 ab 43 ab
ETMT 0.75 1.18 a 5.2 a 46 ab
Difolatan 0.31 1.19 a 5.9 cdef 43 ab
Bay 22555 0.95 1.25 a 5.7 bcde 49 ab
Difolatan 2.50 1.30 a 6.0 def 42 ab
Captan 1,25 1.51 ab 5.3 ab 38 ab
ETMT 0.38 1,53 ab 5.3 ab 43 ab
Bay 22555 0.10 1.56 ab 5.3 ab 49 ab
Bay 22555 0.21 1.64 ab 5.4 ab 31 ab
ETMT 1.50 1.66 ab 5.6 abcd 64 a
Chloroneb 0.95 1.87 abc 5.7 bcde 23 ab
Chloroneb 0.48 2.35 bc 5.5 abc 36 ab
ETMT 0.19 2.55 c 5.3 ab 29 ab
Chloroneb 0.24 3.64 d 5.4 ab 29 ab
Control-plug-mix 3.74 d 5.3 ab 30 ab
Control-soil -- -- 0.2 b
Control-uninoculated 1.00 a 5.2 a 32 ab
soil

a/ Gm active ingredient of fungicide per 1000 gm dry weight Jiffy Mix Plus.

b/ Disease severity index = ratings of disease severity divided by number of
plants rated. Rating = 1) no disease; 2) few lesions; 3) moderate lesions;
4) severe lesions, roots completely brown; 5) plants dead, damped-off.

c/ Emergence Index= Sum of(# seedlings emerging per day:x days after planting)
Total emerged

d/ Numbers in column followed by the same letter are not significantly
different at the 5%7 level by Duncan's Multiple Range Test.










Table 2. The effect of fungicides added to plug-mix on severity of combined
Pythium myriotylum and P. arrhenomanes inoculum on tomato seed-
lings, emergence rate of tomato seedlings and appearance of seed-
lings at two weeks after planting.


Fungicide
ETMT
Difolatan
Bay 22555
ETMT
Captan
Bay 22555
Captan
Bay 22555
ETMT
Captan
Difolatan
Dithane M-45
Dithane M-45
Dithane M-45
Basic CuS04
Basic CuS04
Difolatan
Dithane M-45
Basic CuS04
Control
Basic CuSO4
Uninfested
control


Ratea/
3.00
0.50
0.60
1.50
1.25
0,30
2.50
1.20
0.75
0.67
0.25
2.50
0.67
1.25
2.50
1.25
0.13
0.38
0.67

0.38


DSIh/
1.00 a0/
1.03 a
1.05 a
1.08 a
1.11 a
1.12 a
1.12 a
1.14 ab
1.18 ab
1.35 abc
1.36 abc
1.70 bcd
1.80 cde
2.19 de
2.30 ef
2.77 fg
2.81 fg
3.21 g
3.92 h
4.47 i
4.70 i


Emergence Index-/ Appearance&
7.2 efe/ 1.0 a
7.4 fg 3.0 c
6.9 def 1.2 ab
6.2 abc 1.0 a
7.3 fg 2.2 de
6.7 bcdef 1.4 abc
7.2 ef 2.8 ef
7.9 gh 2.0 cd
6.3 abcd 1.0 a
7.2 ef 1.4 abc
6.7 bcdef 2.0 cd
8.0 h 1.8 bcd
6.8 cdef *
7.3 fg *
5.9 a *
6.1 ab *
6.5 abcde *
6.4 abcd *
*
*
*


5.9 a


1.0 a


a/ Grams active ingredient of the compound per 1000 gms dry weight Jiffy Mix.

b/ Disease severity index = ratings of disease severity divided by number of
plants rated. Ratings = 1) no disease; 2) few lesions; 3) moderate lesions;
4) severe lesions, roots completely brown; 5) plants dead, damped-off.

c/ Emergence Index = Sum of(# seedlings emerging per day x days after planting)
Total emerged

d/ Subjective rating of appearance of healthy plants at time
roots examined e.g. 10 days after planting. Rating = 1) appearance of
plants same as that in uninfested control; 2) Plants slightly smaller than
control, roots in some cases slightly stunted; 3) plants very much smaller
than control, roots stunted and in the case of Difolatan having yellowish
cast.

e/ Numbers in a column followed by the same letter are not significantly dif-
ferent at the 5% level by Duncan's Multiple Range Test.


* Too few plants survive to include in statistical analysis.


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