Group Title: Indian River Field Laboratory mimeo report
Title: Bacterial leaf spot of tomatoes
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Permanent Link: http://ufdc.ufl.edu/UF00056003/00001
 Material Information
Title: Bacterial leaf spot of tomatoes its dissemination and control problems
Series Title: Indian River Field Laboratory mimeo report
Physical Description: 11 p. : ; 28 cm.
Language: English
Creator: Indian River Field Laboratory
Publisher: Indian River Field Laboratory
Place of Publication: Ft.Pierce
Publication Date: 1966]
 Subjects
Subject: Tomatoes -- Diseases and pests -- Florida   ( lcsh )
Tomatoes -- Diseases and pests -- Control -- Florida   ( lcsh )
Leaf spots -- Florida   ( lcsh )
Genre: non-fiction   ( marcgt )
 Notes
General Note: Caption title.
General Note: "May 11, 1966."
 Record Information
Bibliographic ID: UF00056003
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 67709879
clc - 000459078

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The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida






Sj-L kk-~

Indian River Field Laboratory 1.imeo Report IRL 66-4 -:
BACTERIAL LEAF SPOT OF May 11, 1966
TOMATOES
ITS
DISSEMINATION AND CONTROL
PROBLEMS

Bacterial leaf spot of tomatoes caused by Xanthomonas vesicatoria (Doidge)
Dows should be considered primarily as a wouhd incited disease of tomatoes in
the field and treated accordingly by commercial growers and companies involved
in the production of agricultural chemicals.

Source of inoculum.--Xanthomonas vesicatoria can be isolated from tomatoes,
peppers, and nightshades throughout the year in Florida. Tomato fruits (green
or ripe) and stems retain viable bacteria for 1-1 months after a harvested field
is plowed in. Infested sand in the field acts as secondary source of inoculum.
Bacteria can be isolated from rain water collected from roof drains hundreds of
yards away from a tomato field. This is suggestive of the role of wind and rain
in the dissemination of the bacteria.

Infection.--Natural openings such as hygropores and stomates provide a very
small portion of avenues of bacterial entrance into the field grown tomatoes.
Even in the greenhouse, high humidity is required for this type of infection to
take place. Wounding of the epidermis and breaking of the leaf hair are the main
sources of infection. Water-logging of the leaf tissue may enhance entrance of
bacteria.

Factors effecting wounds.--(a) Wind: Wind causes rubbing of the leaves and
branches which bring about breakage of hundreds of leaf hair which provide
openings for bacterial entrance.
(b) Rain: (1) Direct impact of a rain drop causes leaf hair breakage or may
push one leaf against others causing leaf hair breakage. (2) Indirectly, rain
splash carries infested sands whihh upon impact with the leaf surface breaks
epidermis and introduces bacteria into the wound. (3) Rain water produces a
continuous film on the leaf surface, hence facilitating movement and introduction
of bacteria into a clean wound.
(c) Sand: Sand is the most abrasive component of wounding factors in
Florida tomato growing areas. Sand in combination with rain and wind can
disseminate bacterial spot disease of epidemic proportions in a tomato field,
while 9 to 10 days earlier only slight to moderate disease conditions existed.
(d) Impact: Any medium which hits the tomato leaf with an impact strong
enough to break leaf hair or epidermis, opens entrance for bacteria. Conventional
high gallonage-high pressure spray methods fit such a medium.

Temperature and humidity.--Bacterial leaf spot requires high temperature and
high moisture for its development. During the months of July, August, September,
and October (see following table) the environmental conditions coincide with the
rapid growth of the fall crop


/~-rC --<^\-~




'& I
*I*-^








Table.--Monthly average of rainfall and temperature for 13 year period -2-
between 1952-1965
Months
Weather Data J. F. M. A. M. Je. Jy. A. S. 0. N. D.
Rainfall
in inches 2.16 3.57 3.56 3.41 4.46 6.98 8.25 7.`6 8.43 8.25 2.24 2.09

Temperature
in day/month
above 700F 0.0 0.07 0,14 0.84 3.78 12.00 23.42 26.42 22.71 8.5 0.42 0.0


Effectiveness of present bactericides and their application.--(a) Strepto-
mycin sulfate: Only strain of X. vesicatoria which is susceptible to the anti-
biotic is affected when sprayed. Application with streptomycin kills bacteria
present on the tomato plant. However, it does not prevent lesion formation
through wounding and does not slow down the development of the infection or
reduce the size of the lesions formed. But, when lesions reach maturity, all
or the great majority of the bacteria within the lesions are eliminated.

Application of streptomycin does not change the response of the susceptible
strain toward resistance, or the absence of streptomycin does not induce reversion
toward susceptibility. However, in a mixed population, application of strepto-
mycin acts as a screening device in favor of the resistant components of the
bacterial population.

Test of several experimental and new systemic bactericidea and antibiotics
in the greenhouse with streptomycin-resistant strain of X. vesicatoria showed no
promising new product.
(b) Dithiocarbamates plus copper sulfate: This mixture eliminates both
streptomycin resistant and susceptible strains of X. vesicatoria lodged on the
tomato plants. But it does not erradicate existing mature lesions. However,
the second important role of this mixture is its retarding of the infection
development. It also reduces the size of the mature lesions.

The reason for the above responses to maneb-copper mixture is most likely
in the reduction of the number of bacteria which enter the wounds and the sub-
sequent maturing of the leaf tissue which adversely effect lesion size.

Recommendations.--(a) Sanitation: These recommendations mainly concern
the fall crop of ground tomatoes.

If the fall planting is next or close to the spring crop the following
precautions may help to delay the outbreak of bacterial leaf-spot .in the field.

1. Do not locate the fall field where prevailing winds pass over the field
where spring crop was planted.

2. Destroy the spring vine as soon as possible after the harvest. This
should give enough time for fruit and plants to deteriorate.

3. Destroy volunteer tomatoes and nightshade.

4. If possible, do not run the irrigation water through the old field into
the new field.










5. If fall seedlings have already emerged, but tractors are used in discing
volunteers in the old field, wash the tractor wheel and discs before returning
into the new field.

6. Some cheap methods should be used to pack the sand on field roads.

(b) Protection: (1) Maneb plus copper sulfate. Good spray coverage from the
time seedlings emerge is an essential part of protection against bacterial leaf
spot. The practice of spraying to the point of run-off should be continued.

Interval between sprays should not exceed 6 days and 3 days is the minimum
requirement.

Until data is gathered on different pump pressures in relation to bacterial
spot infection, an arbitrary maximum of 100 P.S.I. is recommended for spraying.

Note.--In a field where bacterial leaf spot is present, avoid repeated sprays
with only insecticides or a fungicide which does not kill bacteria on plant surface.

(c) Irradication: The presence of even few bacterial leaf spot in the field
should not be overlooked. Samples of doubtful appearing leaf spots could be sent
to I.R.F.L. for streptomycin reaction tests. When suggested, 3 applications of
streptomycin should be sufficient for irradicating the susceptible strain.










TABLE 1T.

EFFECT OF DIFFERENT INOCULATION PROCEDURES
ON BACTERIAL LEAF SPOT DEVELOPMENT
ON TOMATO SEEDLING GROWN IN THE GREENHOUSE


Number
of


Water


Respbnse/to Treatment
Sand Blast/
Bacterial Sterile Sand +
Sterile Infested Bacterial


Bacterial


Seedlings Spray Sand Sand Suspension Suspension

1 1 1 2 5 3
2 1 1 3 5 2
3 1 1 2 5 2
4 1 1 3 5 2
5 1 1 3 4 1
6 1 1 1 5 1
7 2 1 2 5 1
8 1 1 3 5 1
9 1 .1 2 5 1
10 1 1 1 5 3

Ave..2/ 1.1 1.0 2.2 4.9 1.7

a/ Disease Rating:
1 = no response
2 = leaf drooping
3 = few scattered lesions
4 = moderate infections, plant green
5 = heavy infection, chlorosis, wilting and curling of leaves, leaf dropping.

b/ Fine sand blown through Smith Pestmaster Garden Duster.

c/ Rated 12 days after inoculation.


NOTES:


L I i I








TABLE 2.


EFFECT OF DIFFERENT INOCULATION PROCEDURES
ON BACTERIAL LEAF SPOT DEVELOPMENT
ON TOMATO PLANTS GROWN IN THE FIELD


Sterile
Sand
Blast
Replicate/
A B C.


Number of Spots Per Leaflet
in Treatment
Sand Blast
and Bacterial ]
Suspension
Replicate
A B C


Bacterial
Suspension/
Replicate
A B C


1 0 0 0 22 45 93 0 0 0
2 0 0 0 46 39 7 0 0 1
3 0 0 24 95 93 0 0 0
4 0 0 0 2 43 26 0 0 0
5 0 0 2 72 46 73 0 0 1
6 0 0 0 62 16 36 0 0 0
7 0 0 0 16 59 7 0 2 1
8 1 0 0 31 35 4 0 0 0
9 0 s o 11 8 19 *0 o
10 2 0 0 76 1l 14 1 0 o
11 0 0 1 10 19 7 0 1 0
12 0 0 0 24150 48 0 0 0
13 0 0 0 1ll 9 6 0 0 0
14 0 0 3 6 48 2 0 0 0
15 0 0 0 22 17 29 0 0 0
16 0 0 0 4 7 12 0 0 0
17 0 0 0 52 52 2 0 0 0
18 o o o 48120 8 o o
19 o0 1 7 17 86 0 0 0
20 0 0 0 27 19 50 0 0 0
21 0 0 1 3215D 85 1 0 0
22 0 0 0 30 78 20 2 0 0
23 0 0 0 19 65 19 0 0 0
24 0 0 4210C 51 1 0 0
25 0 0 0 14 22 36 1 0 0

Ave .C./per ,/>
Leaflet. ., 0.15 38.8 -4e

a/ 20 feet portion of a row which included 10 plants.

b/ Spray at 5 P.S.I.

c/ Data gathered 5 days after inoculation.


NOTES:


Leaflets
Sampled
at
Random













AROUND BACTERIAL


STABLE 3.

INFESTED FIELD SOIL,
LEAF SPOT INFECTED VOLUNTEER TOMATOES,
AS INOCULUM SOURCE


Sterile
Sand Blast
+ Water


-Number- of- Spots/Per
Plant in'
Sterile.Sand
Blast +-Bacterial
Suspension


Field Soil
Blast +
Water


1 0 100's 11
2 0 100's 8
3 0 100's 21
4 0 100's 25
5 0 100's 46


a/ 1 days after inoculation.


TABLE 4.

DISTRIBUTION OF.BACTERIA PRESENT ON YOUNGEST
MATURE LEAFLETS LOCATED AT THREE DIFFERENT VINE HEIGHTS;
SAMPLES COLLECTED AFTER TWO DAYS OF HEAVY RAINS


Field
Replicated/


Number of Bacterial Colonies
Per 0.01 ml of Sample Suspension
18-24" 6-10" Ground
Above Ground Above Ground Level


9
60
150


1,000
60
15
200
65


1,00
150
200
1,000
200


_Ave. _.


228


a/ ~i) leaf plugs (I inch diameter) per replicate.


NOTES:


Plant
Number


510







-7-


TABLE 5.


EFFECT OF TIME BETWEEN FUNGICIDE
(DIATHANE M-45 1.5 LB. & TBCS 4 LB.)
AND INOCULATION (SAND BLASTING + BACTERIAL
ON DISEASE INCIDENCE


Days Between
Fungicide Spray and
Tnnrml ati nn


SPRAY
SUSPENSION)


AverageA/Number of Lesions Per Plant
1 2 3 4 Mean


7 365 215 195 92 276
3 30 179 157 194 140
0 293 59 105 211 167
No fungicide 375 213 139 70 199


a/ Average of 4 leaves per plant
infected leaf.


(replicate) starting from youngest


TABLE 6.


EFFECT OF TIME BETWEEN INOCULATION
AND FUNGICIDE SPRAY ON DISEASE INCIDENCE


Hours Between
InoculationS and


Approximate number of Spots Per Plant


Fungicide Spray 1, 2 3 4, 5 6 Mean

24 hrs. 500 1,000 500 1,000 1,000 500 750
12 hrs. 1,000 1,000 500 1,000 1,000 500 800
6 hrs. 500 240 500 500 -1,000 500 500
0 hrs. 200 1,000 500 500 1,000 500 600
No fungicide 500 1,000 1,000 1,000 500 1,000 800


a/ Sand blasting and bacterial suspension spray (5 P.S.I.)


NOTES:










TABLE 7.

EFFECT OF HIGH PRESSURE (300 P.S.I.)
HIGH GALLONAGE 150 GAL./A) CONVENTIONAL SPRAY
ON BACTERIAL SPOT INCIDENCE ON TOMATOES
GROWN IN GREENHOUSE


Bacterial
Suspension
Plus


1 2


.'Number of Bacterial Spot/F1ant._q/


1? 4 5 6 7


6 9 10 Mean


0 50 0 0 10


10 25 0


High Pressure
Water Spray

High Pressure
Fungicides/Spray

Sand Blasting
No Spray


a/ Data obtained


25' 600 1o000 200 300' 400 1,000 1,000- 200 300


100 1,000


50 1,000 10


500


6o0


0 1,000 1,000 1,000 1,000


10 10 10 10 10 10 10 10 10 10
10 10 10 10 10 10 10 10 10 10


1,000,000


12 days after inoculation.


.b/ Manzate D 1.5 + TBCS 4 lb.


TABLE.8.

EFFECT OF HIGH PRESSURE (300 P.S.I.)
HI&II VOLUME (150 GAL./A) CONVENTIONAL SPRAY
ON BACTERIAL SPOT INCIDENCE ON TOMATOES G1iOWN IN FIELD


Treatments-a/


Percentage of Foliage Infected Per Replicate'Mean
1 2 .3 4 5 6 7. 8 '


Fungicide only 0 0 0 0 0 0 0

Bacteriab/only 60 40 40 30 70 80 60 80

Bacteria + Water
Spray (300 P.S.I.) 80 80 30 70 70 70 60 80

Bacteria + Fun-
gicideS/(300 P.S.I.) 80 80 20 50 90 60 70 70

Bacteria + Fun-
gicide (5 P.S.I.) 70 50 70 30 80 50 60 60


0

57.5


67.5


65.0


58.75


NOTES:


No spray


0 100


a/ Inoculated with bacterial suspension at (5 P.S.I.) at 4-14, 4-21 & 4-28, 1966.
b/ Streptomyin resistant.
c/ Diathane M-22 special, 1.5 lb. + TBCS 4 lbs.
Note. Heavy winds throughout the experiment duration.


1 2


.









TABLE 9.

TOXICANT EVALUATION EXPERIMENT

Fall, 1965


Diseases
Bacterial Leaf Spot Rhizoctonia Early Blight Average of Yield and Growth/Vined/
Total Number Weight Weight of
NumberJ/ Number of of Above
of Spots/ Stem Fruit Ratingb/ of Mature Mature Ground
Treatment and Rate Rating Leaflet Pating/ Canker Rot % Fruit Green Green Growth
lbs./100 gal. 10/18/65 10/18/65 /16/65 10/22/65_ Set Fruit (in pounds) (in pounds)


Average'/
Yield
Per
Acre


Water (control)
Tribasic Copper Sulphate
4.0 lbs.

Dithane M-45, 1.5

Manzate D + TBCS,
1.5 + 4.0

M-45 + TBCS, 1.5 + 4.0

Agri Mycin 17, 200 ppm


3.2

2.8

2.0


1.0


5.0


3.6

3.2


2.6


40 16.3

34 20.6

34 13.8


23 10.3

6 10.3

50 18.5


2.2

2.0


1.2

1.2

2.0


22.2

23.7

27.9


26.5

27.7

24.4


5.5

6.3

7.0


0.9

1.1

1.6


2.0

C.9


2.1

2.2

2.0


2.7

2.6

2.1


70.8

87.7

125.6


163.3

62.8


Average of 5 replicates. Disease index based on: 0 = no infection to 5 all leaves infected and lower leaves discolored.
Average of 5 replicates. Disease index based on: 0 = no infection to 5 heavily infected.
Average of 10 randomly picked per each of 5 replicates or 50 leaflets.
Surviving plants only.
Number of 40 pound boxes per acre


NOTES:









-10-


SEASONAL VARIATION III XAYTHCMONAS VESICATORIA POPULATION
SAMPLED FRCM TCMATO FIELDS


XXX KY


1 (r- Y


Sx


Sept. Oct. Nov. Dec.

-----------1965------------


Jan. Feb. Mar. Apr. May

--------------1966--------------







o TABLE 10.
o Mo
TOXICANT EVALUATION EXP:hIMENT
Spring, 1966

Disease Rating/ __ Yield (first harvest)
Worm Number of Weight
Gray Fruit Damaged Total Marketable Mature
TreatmentS/and Rate Leaf Early Botrytis Rot Fruit Number Mature Green
lbs./100 gal. S_ Spot Blight_ Blight .. ...Harvest Green (lbs./A)

Watei (control) 5 3.8 2.8 13.0 13.6 375 216 3,687

Manzate D, 2.5 2 1.0 2.8 8.5 12.3 503 328 6,300

Diathane M-45, 2.5 1.8 1.2 2.4 11.6 8.0 546 343 6,487

Difolatan, 2.5 1.2 1.4 1.6 1.8 5.5 545 318 5,772

Laconil 2787, 2.5 1.8 1.6 1.4 3.8 6.3 552 380 6,830

Du Pont 328, 2.5 2.3 2.2 3.4 7.4 13.3 531 362 6,223

Dyrene, 1.0 3.0 2.4 1.8 7.2 10.0 485 290 5,290

Daconil 2787 + Difolatan
1.5 + 1.5 1.0 1.0 1.2 1.8 4.1 464 317 5,430

Dyrene + Manzate D
1.0 + 1.5 1.4 1.0 1.4 4.0 12.0 590 323 5,710

a/ 18 sprays during 22 months of growth.
E/ 1 = no infection and 5 = heavy infection.
/ Percent of marketable fruit, includes both Rhizoctonia and Botrytis rot.
/ Percent of total fruit; 9 insecticide sprays.
I







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