PENNSYLVANIA VEGETABLE DISEASE UPDATE
JULY 10, 2013
Beth K. Gugino
Assistant Professor Vegetable Pathology
Department of Plant Pathology
and Environmental Microbiology
219 Buckhout Lab
University Park, PA 16802
Phone: 814-865-7328
Email: bkgugino@psu.edu
Web: http://extension.psu.edu/plants/vegetable-fruit
TOMATO/POTATO EARLY BLIGHT WEEKLY UPDATE
The TOM-CAST disease forecasting model is a tool for helping tomato/potato growers decide when to
apply fungicides for managing early blight as well as Septoria leaf spot (tomato only). Below are the daily,
weekly and total summed disease severity values for 16 locations across Pennsylvania. The TOM-CAST
model is run using interpolated atmospheric weather data by ZedX, Inc. (not specific field-based weather
stations). Since environment varies, sometimes within relatively short distances, the spray
recommendation information should be considered in combination with your local environmental
conditions.
During this past week all 16 locations listed in the table have reached the 35 cumulative DSV threshold to
trigger the application of a fungicide. Please consult the 2013 Pennsylvania Vegetable Production Guide
for specific product and rate recommendations (http://extension.psu.edu/plants/vegetable-fruit/). Keep
in mind that for potato early blight inoculum is typically present in the field around July 4th. For earlier
planted cultivars this can coincide with the transition of the crop from flowering to tuber formation, a
more susceptible stage in the phenology of the crop. For tomatoes, once any fruit start to ripen, regular
fungicide applications may be warranted.
Table 1. Actual daily disease severity values (DSV) from July 3 through July 9, forecasted DSV for July 10
through 13 and total accumulated DSVs since June 1, 2013 for 16 locations across Pennsylvania.
June daily DSVs
Town
County
3
4
5
6
7
8
9
Total
weekly
accum.
DSV
Forecasted Aug
DSVs
10
11
12
13
Total
accum.
DSV June
1 to July 9
Fairview
Erie
1
1
2
3
1
1
0
9
4
4
0
0
44
Corry
Erie
3
3
3
3
3
3
3
21
5
5
1
0
73
Sweden Valley
Potter
4
4
4
4
4
4
4
28
4
4
1
1
78
Butler
Butler
3
1
1
1
2
2
2
12
3
3
0
0
50
Finleyville
Washington
3
0
0
1
1
1
2
8
2
3
0
0
42
Loretto
Cambria
3
4
4
4
4
4
4
27
3
4
0
0
75
Rock Springs
Centre
3
4
4
1
2
1
2
17
4
5
0
0
57
Jersey Shore
Lycoming
3
3
0
1
2
1
2
12
4
5
5
0
38
Clarks Summit
Lackawanna
3
3
1
0
1
0
1
9
2
3
4
1
38
Wyoming Valley
Luzerne
3
3
1
0
1
1
1
10
2
3
4
1
40
Germansville
Lehigh
4
4
4
4
4
1
1
22
2
3
4
1
58
Kutztown
Berks
3
2
2
1
1
1
2
12
2
3
4
1
44
Ringtown
Schuylkill
4
4
4
4
1
1
2
20
2
3
3
1
63
Gratz
Dauphin
3
0
1
1
1
1
2
9
4
5
5
0
47
Leola
Lancaster
3
3
3
1
0
1
2
13
3
4
4
1
52
Landisville
Lancaster
3
3
3
1
0
1
2
13
3
4
4
0
56
----Information provided is intended for consideration by the user, but is not intended to be a recommendation. Production decisions
should be based on consideration of many types of information (scientific, experimental, economic, legal, etc.) available to the user.
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