Title: Comparison of foliar fungicide spray combinations for management of diseases of tomato
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Title: Comparison of foliar fungicide spray combinations for management of diseases of tomato
Series Title: Comparison of foliar fungicide spray combinations for management of diseases of tomato
Physical Description: Book
Creator: Pohronezny, Ken,
Publisher: Everglades Research and Education Center, IFAS, University of Florida
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Bibliographic ID: UF00080909
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
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Resource Identifier: oclc - 173682851

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EV-1998-2

Comparison of Foliar Fungicide Spray Combinations for
Management of Diseases of Tomato
University of Florida
Ken Pernezny, Everglades Research and Education Center, IFAS, University of Florida
and Peter J. Stoffella, Indian River Research and Education Center, IFAS, University of
Florida, Ft Pierce, FL

The major intent of this study was to evaluate selected fungicides for efficacy as
foliar sprays for management of major foliar diseases of fresh-market tomato in Florida.

Materials and Methods

This study took place on the campus of the Indian River Research and Education
Center, Ft Pierce, FL. Tomato plants, cv. Agriset 761, were transplanted to the field on 10
March 1998. Transplants were grown from seeds placed in Styrofoam trays on 8 February.
Transplants were setinto plastic-mulched, non-fumigated, raised beds. Beds were spaced
seven feet apart center to center with the seedlings spaced two feet apart within the row.
Soil was Oldsmar Fine Sand. The air temperature the day of transplanting ranged from a
low of 38* F to a high of 74 F. Seedlings were watered in with Admire (imidacloprid) (24
fluid ounces per acre) primarily for the control ofwhiteflies. Plants used in the guard rows
were donated by a grower and were not transplanted until 13 March. Methomyl and
endosulfan were sprayed on an as-needed basis for management of foliar and fruit-eating
insects.

An application of 4N-16P-4K fertilizer was broadcast preplant at 685 lbs/A and
incorporated into the bed. Additional 8N-12P-20K fertilizer at a rate of 1369 lbs/A was
split into two bands near shoulders of each bed before covering with plastic mulch. Heavy
wind damage around the middle of March adversely affected plant growth, but plants
recovered by the beginning of April.

The experimental design was a randomized complete block with four replications
of each of 9 treatments:

1. Bravo Ultrex, 8.3 g/gal weekly
2. Bravo Ultrex, 4.2 g/gal twice a week
3. Bravo WeatherStik, 9.4 ml/gal weekly
4. Bravo WeatherStik, 4.7 ml/gal twice a week
5. Quadris, 1.81 ml/gal and Kocide, 9.1 g/gal twice; then Bravo Ultrex, 5.9
g/gal and Kocide, 9.1 g/gal throughout season
6. Quadris, 1.81 ml/gal and Kocide, 9.1 g/gal alternated weekly with Bravo
Ultrex, 5.9 g/gal and Kocide, 9.1 g/gal throughout season
7. Quadris, 1.81 ml/ gal and Kocide, 9.1 g/gal alternated weekly with Dithane,
9.1 g/gal and Kocide, 9.1 g/gal
8. Bravo Ultrex, 5.9 g/gal weekly







9. Untreated control


Applications of treatments were made with a hand-held three-gallon garden sprayer with
thorough wetting of foliage to run-off. A particular effort was made to penetrate the plant
canopy and to ensure that fruit surfaces were sufficiently covered. Weekly sprays were
initiated on 17 March and were continued through 29 May.

Plots were rated for disease weekly beginning 5 May using the method of Pernezny
et al (1996). An estimate of the percentage of foliage covered by disease and foliage lost
due to disease were combined into one rating. The proportion of plants with any visible
foliar disease was determined based on a count of the number of plants in a plot This
proportion was multiplied by another representing an estimate of the average amount of
foliar damage per infected plant in order to arrive at a final proportion of diseased plant
material per plot

Ten plants from the interior of each plot were harvested and graded on 19 May, 26
May, 2 June, and 11 June. Fruit were counted, weighed and sorted into several defect
categories, including target spot and early blight

Data were analyzed by analysis of variance using the Statistical Analysis System
(Cary, NC). Where F-tests indicated a significant difference among an array of three or
more means, means were separated by Duncan's procedure. A series of pre-planned,
single degree-of-freedom orthogonal contrasts were also used for specific comparisons.

Results and Discussion

Although target spot was the primary disease for which data were needed in this
test, virtually no target spot appeared. It may have been too warm for target spot,
especially by the time of fruit set when this disease usually becomes most destructive.
However, a substantial epidemic of early blight did develop, allowing for an excellent
evaluation of the fungicides for this disease.

All fungicides reduced foliar early blight compared to the control (Fig. 1).
Treatments containing Quadris were particularly effective, significantly reducing foliar
disease ratings over other fungicide treatments as well as the control (Table 2).

No significant differences were noted in total or marketable yield (Table 1) using
a standard multiple range mean separation procedure. However, using contrasts,
treatments did significantly improve marketable yields (Table 2). Likewise, early blight
and sunscald injury to fruit were significantly less in sprayed plots.

Literature Cited

Pernezny, K., Datnoff, L. E., Mueller, T., and Collins, J. 1996. Losses in fresh-market
tomato production in Florida due to target spot and bacterial spot and the benefits
of protectant fungicides. Plant Disease 80:559-563.









Table 1. Yields, cull rates, and disease ratings for tomato foliar disease experiment, Ft. Pierce, FL,
spring, 1998.



Culls (Percentage of Total Harvest)

Marketable Average Fruit
Treatment' Weight (lb)b Size (lb) Sun scald Early blight Target spot Rhizoctonia


136.8 ns"

142.6

130.1

116.1

109.2

121.7

139.6

133.3

106.0


0.39 ns

0.31

0.37

0.38

0.37

0.40

0.41

0.39

0.40


12.8 ab

14.6 ab

10.2 b

14.5 ab

15.0 ab

14.4 ab

11.1 b

15.3ab

21.9 a


0.24 b

0 b

0.04 b

0 b

0.05 b

0 b

0 b

0.08 b

2.30 a


0.18 ns

0.06

0.13

0

0

0

0.17

0.32

2.45


0.99 ns

0.72

0.14

0.09

0

0.06

0

1.10

0.58


STreatments were as follows: 1 Bravo Ultrex, (1.82 lbs/a) weekly; 2 Bravo Ultrex,(0.91 Ibs/a) twice
a week; 3 Bravo Weather Stik, (2.0 pt/a) weekly; 4 Bravo Weather Stik, (1.0 pt/a) twice a week;
5 Quadris (0.1 lb/ai)+ Kocide (2.0 lb/a) twice alternating with Bravo (1.1 lb/ai)+ Kocide (2.0 lb/a) once,
throughout season; 6 Quadris (0.1 lb/ai)+ Kocide (2.0 lb/a) alternating weekly with Bravo (1.1 lb/ai)+
Kocide (2.0 lb/a); 7 Quadris (0.1 lb/ai)+ Kocide (2.0 lb/a) alternating weekly with Dithane (2.0 lb/a)+
Kocide (2.0 lb/a); 8 Bravo (1.1 lb/ai) + Kocide (2.0 lb/a), weekly; 9 untreated control.

b Weights are the mean of four harvests in 1998 (May 19, May 26, June 2, and June 11).

C Means in columns followed by the same letter are not significantly different by Waller-Duncan's mean
separation test; ns = not significant.







Table 2. Selected single-degree-of-freedom contrasts for yield parameters fruit damage and disease ratings for
tomato foliar disease experiment, Ft. Pierce, FL, spring, 1998"




F-testb

Fruit damage from

Contrast Marketable yield" Early blight Sunscald Foliar disease rating
Control vs. treated 4.71 48.3 ** 12.9 ** 94.9 **

Quadris combinations vs. other fungicides 1.32 0.00 0.08 17.5 **

Bravo Ultrex vs. Bravo WeatherStik 2.56 0.19 1.92 0.11

denotes significant differences) at P = 0.05.
** denotes significant differences) at P = 0.01.

b Contrast F-tests show that fungicide treatments in general reduce foliar disease, reduce losses from sunscald and early
blight fruit infection, and are associated with increased marketable yields. Quadris, in combination with other fungicides,
also was superior for management of foliar symptoms of early blight.

0 Disease rating was made on 11 June 1998.








100- Ft Pierce Spring 1998


Treatment
80 -
2
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0 I ---- s -

4: -- .. -
M 50 Ma 2 Ma /9
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'I 0 /T T :
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0 20-

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May 5 May 12 May 19 May 26 June 2 June 11
Date
Figure 1
Treatments were as follows: 1 Bravo Ultrex, (1.82 lbs/a) weekly; 2 Bravo Ultrex,(0.91 lbs/a) twice a week; 3 Bravo Weather Stik, (2.0
pt/a) weekly; 4 Bravo Weather Stik, (1.0 pt/a) twice a week; 5 Quadris (0.1 lb/ai)+ Kocide (2.01b/a) twice alternating with Bravo (1.1
lb/ai)+ Kocide (2.0 lb/a) once, throughout season; 6 Quadris (0.1 lb/ai)+ Kocide (2.0 lb/a) alternating weekly with Bravo (1.1 lb/ai)+ Kocide
(2.0 lb/a); 7 -Quadris (0.1 lb/ai)+ Kocide (2.0 lb/a) alternating weekly with Dithane (2.0 lb/a)+ Kocide (2.0 lb/a); 8 Bravo (1.1 lb/ai) +
Kocide (2.0 lb/a), weekly; 9 untreated control.




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