CHEMICAL CONTROL OF ANTHRACNOSE
AND
SEPTORIA LEAF BLIGHT ON PROCESSING TOMATO, 1999
TOMATO
(Lycopersicon esculentum cv Peto 696) ,
Anthracnose; Colletotrichum coccodes ,
Septoria Leaf Blight; Septoria lycopersici
R. M. Riedel, Rebecca Lyon, Gretchen Sutton
Department of Plant Pathology
Mark Schmittgen,
Department
of Horticulture & Crop Science
The Ohio State University
Columbus, OH 43210
CHEMICAL CONTROL OF ANTHRACNOSE AND
SEPTORIA LEAF BLIGHT ON PROCESSING TOMATO, 1999: The test was conducted at the
Waterman Farm, The Ohio State University, Columbus, OH (Franklin Co). on Miami
Silt Loam in an area cropped to tomatoes the previous 5 years. Plots were
single rows 30 ft long bordered by untreated tomato rows. Rows were 5 ft apart
on center with plants 12 in apart in the row. Plots received 100 lb/A N plowed down. Treflan 4E (1.5
pt/A) and Sencor DF (0.5 lb/A) were applied for weed control. Greenhouse-grown
tomato seedlings cv Peto 696 were set May 14. Fungicides were applied at 65 psi
in 50 gal water/A using an R&D CO2-powered, tractor-mounted sprayer with a
one-row boom carrying 5 Delavan HC-8 tips. All treatments were replicated 4
times in a randomized complete block design.
All fruit from the center 5 ft of each treated row were hand harvested
on Aug 24. Fruit was hand sorted into marketable red and green, anthracnose,
and ground rot (Pythium spp.+ blossom end rot) and mechanical cull categories.
Plots were inoculated 3 times in July with Alternaria solani, twice applied to
the guard rows and once over treatment rows. Foliar rating Early Blight was
made Aug 23. Rainfall in the test area
in May, Jun , Jul, and Aug, was 1.37, 1.65, 2.78, 2.78 and 2.61 in., respectively. Irrigation was
applied when needed.
Anthracnose development was slight in
part because of the tolerance of 696 to anthracnose and in part because of the
low rainfall and low relative humidity during the growing season. Ground rot development was slight. A large
portion of the mold category consisted of fruit with Blossom End Rot
secondarily infected with Alternaria tenuis.
Blossom End Rot developed well because of fluctuating soil moisture
conditions early in the growing season. Early Blight developed well on foliage,
but there were no fruit symptoms.
Standard fungicide disease control
programs, Bravo Ultrex at 2.75 lb/A, Dithane DF at 3.0 lb/A and Manzate 200 at
2 lb/A on weekly schedules were not better than check in terms of marketable
red yields. Bravo Ultrex and Dithane
programs were better in terms of marketable green yield. The Quadris-Bravo Ultrex program in which
Quadris and Bravo were applied at high rates was better than check and standard
fungicide programs in terms of marketable red yields. Considering disease control, all fungicides were better than check in control of Anthracnose, but there
were no differences between treatments.
There were no differences between treatments or check in the control of
Ground Rot (Table 1).
In the predictive spray programs whether
run with data from ground based weather data (CR-10) or remote data (Skybit),
there was no difference except in the case of Bravo Ultrex in terms of green
yield. All treatments gave better
control of Anthracnose than
check .
It should be noted that, as in years past, Quadris appears to fit into
the TOMCAST system as an exact substitution for Bravo Ultrex in terms of DSV
intervals and spectrum of activity.
Usually Quadris is superior in terms of Ground Rot control. This year it was not challenged because of dry
weather.
Table 1: Control of Diseases on
Tomato Peto 696; 1999; Columbus, OH.
KG/5ft of row KG/5ft of row KG/5ft of row
TRT MKT
RED[1] MKT GREEN[2] ANTH[3] GROT[4]
Quadris 2.08F 5.0floz(A,C,G,J) 3.10ab 0.74ab 0.02 bc 0.01 c
Bravo Ultrex
1.4lb (B)
Bravo Ultrex
2.75lb(F,I,L)
*Bravo Ultrex 2.75 lb (A,B,D,F,H,I,K,L) 3.55 ab 0.15ab 0.02
bc 0.03 bc
*Manzate 200 2lb (A,B,D,F,H,I,K,L) 2.35ab 0.28 b 0.04 bc 0.03bc
*Bravo Ultrex
1.44lb (A,B,D,F,H,I,K,L) 3.11ab 0.54ab 0.03 bc 0.03
bc
