Rhode Island Apple IPM

2001 - Current pest report - Apple scab infection periods

McIntosh Tree stage:
4/2/01 - Silver tip
4/9/01 - buds breaking - Green tip
4/18/01 - 1/4 inch green
4/20/01 - 1/2 inch green
4/23/01 - tight cluster
5/1/01 - pink
5/3/01 - bloom
5/12/01 - petal fall?

Apple scab infection periods:
4/12/01 - Wet for more than 24 hours at 51 degrees
4/17/01 - Rain began at 3:30pm and the temperature was 44 degrees. Dropped to 40 degrees for 10 hours, then dropped to 34 degrees for 6 hours by noon on April 18th. It's been wet for nearly 24 hours now, at it is still wet. At 40 degrees, 29 hours of leaf wetness can cause an infection. At 34 degrees, 48 hours of wetness are needed to cause an infection. I am guessing this wet period will be an infection period.
4/20/01 - I am so glad to be wrong! No infection period 4/17/01!
5/15/01 - 5/16/01 Looks like an apple scab infection period. I'll assume there was enough rain to thoroughly wet last year's leaves on the orchard floor. Leaves need to be wet to discharge spores.