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Source R.A. Spotts, Ohio State University
Black Rot is a disease caused by the fungus Guignardia
bidwelli. It overwinters in in old mummified berries. In
spring, the primary inoculum is released which starts the
initial round of infection. Those initial spores are dis-
persed by rain and wind. After the initial infection period,
secondary infections are spread by rain splash. This mod-
el predicts infection periods of Black Rot based upon the
Spotts model.
This model uses temperature and leaf wetness period to
estimate the onset of an infection period. The temperature
is compared with the period of leaf wetness needed to pro-
duce an observable infection. If the wetness period ex-
ceeds the required period for that temperature, the word
RISK will appear
Infection Severity Screen
BLK ROT=RISK PM:
ASC=NONE CON=010
Grape Black Rot
This screen shows a risk for Black Rot as well as Powdery
Mildew. This screen shows a risk for Black Rot.
Temperature (F)
Hours of Leaf Wetness
50
24
55
12
60
9
65
8
70
7
75
7
80
6
85
9
90
12
