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  • Michigan State University Extension
  • Michigan State University Ag Bio Research
  • Project GREEEN

Reeman / Fremont - West Grape Leaf Black Rot Report (Report issued 3/28/2024 19:55 )

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 5/1/2024 as a default date.
Time period assessed for wetting events: 3/14 to 3/28/2024.


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 Reeman / Fremont - West 3/14 Midnight-1AM 3/15 10-11AM Wet: 24
Span: 35
41.5 0.9 No risk until pre-bloom period 4%
2 Reeman / Fremont - West 3/17 2-3PM 3/17 2-3PM Wet: 1
Span: 1
29.1 0.01 No risk until pre-bloom period 0%
3 Reeman / Fremont - West 3/22 10-11AM 3/22 3-4PM Wet: 6
Span: 6
29.1 0.23 No risk until pre-bloom period 0%
4 Reeman / Fremont - West 3/26 Midnight-1AM 3/26 9-10PM Wet: 16
Span: 22
49.4 0.73 No risk until pre-bloom period 29%

*NOTE: Infection is predicted with fewer hours than listed in the 'Wet hrs @ avg temp' column. This can happen when there are falling temperatures. Infection may have occurred early in the period during warm temperatures, but the colder temperatures later in the period decrease the number displayed as the average temperature for the period.