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  • MSU Extension
  • Michigan State University Ag Bio Research
  • Project Greeen

Linwood Grape Leaf Black Rot Report (Report issued 7/31/2015 3:16 )

Wetting periods start with rainfall (at least 0.01 inch) and continue until the start of at least eight hours without moisture (rainfall, leaf wetness, high relative humidity). Wetting periods are classified as "ongoing" until eight consecutive dry hours have passed. After that, the official end of the wetting period is recorded (the start of the 8 hour dry period).

Black rot model available after 4/15. Pre-bloom estimated as 6/6/2015 (800 DD Base 42 after 1/1).
No missing degree day data.
Time period assessed for wetting events: 6/6 to 7/31/2015.

Wet Period Station Start of wetting period End of wetting period Duration (Hrs.) Avg temp (F) Rainfall (in.) Grape Leaf Black Rot Progress toward infection
1 Linwood 7/17 4-5AM 7/17 10-11AM Wet: 7
Span: 7
64.8 0.1 None 82%
2 Linwood 7/21 Midnight-1AM 7/21 10-11AM Wet: 9
Span: 11
63.5 0.02 Yes 100%
3 Linwood 7/25 3-4PM 7/26 7-8AM Wet: 13
Span: 17
65.8 0.17 Yes 151%
4 Linwood 7/29 1-2PM 7/29 10-11PM Wet: 5
Span: 10
78.3 0.5 None 70%