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

Linwood Grape Leaf Black Rot Report (Report issued 5/22/2015 16:34 )

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 not reached. Using 6/1/2015 as a default date.
Time period assessed for wetting events: 5/8 to 5/22/2015.

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 5/9 9-10AM 5/12 Midnight-1AM Wet: 63
Span: 64
52.9 0.43 No risk until pre-bloom period 287%
2 Linwood 5/12 6-7PM 5/12 6-7PM Wet: 1
Span: 1
49 0.01 No risk until pre-bloom period 0%
3 Linwood 5/15 5-6AM 5/16 8-9AM Wet: 21
Span: 28
53.7 0.18 No risk until pre-bloom period 99%