Heavy apple scab pressure April 28 -May 7

Last week, following four scab/rust infection periods during April 28 to May 2, we had four more infection periods: May 2-3: 15 hours wet at 65-58° with 0.1 in. of rain; May 3-4: 16 hr wet at 66-46° with 0.08 in. of rain; May 4-5: 20 hr at 57-48° with 0.4 in. of rain; May 5-7: 38 hr at 54-48° with 0.97 in. of rain. This totals eight infection periods in ten days! Several of these infection periods involved both scab and rusts.

Remaining apple blossoms and small fruit may still be susceptible to quince rust so it is prudent to include a sterol-inhibiting fungicide for after-infection rust control in the next fungicide application. Scab and rust lesions from the Apr 22-23 infection period are expected to start appearing this week.

Fire blight: Continue to protect prolonged bloom as needed. 

Powdery mildew: We have had 21 dry weather “mildew infection days” since mildew spores were first available Mar 16.