Apple scab and winter moth and Zoom meeting

April 23, 2020

There will be another Zoom Twilight Meeting with UMass Fruit Team on Thursday April 30 at 5:30. I think it worked pretty well last time. You’ll need to pre-register for the meeting and this will be emailed to you next week. You can see recordings of the April 9th meeting at:

We are inching towards spring. I like the cool temperatures, but wish the sun would shine more. Apple trees are mostly at tight cluster (still). We haven’t had an apple scab infection period for over a week, but that will end soon – assuming the forecast is correct. According to models we should experience an apple scab infection period on Friday April 24, and a major apple scab infection period starting Sunday April 26 and continuing through Monday. If your trees are not protected with a fungicide going into Friday’s rain, plan to spray a fungicide early Saturday. Spraying a fungicide such as Captan, Syllit, Manzate, and Dithane within 24 hours of an infection period should control scab. And if your fungicide coverage is just fair going into Friday’s rain, plan to spray again on Saturday. The April 26-27 infection period looks like it could be very significant.

This cool weather is keeping insect development slow. Winter moth caterpillar eggs are 95% hatched, but the caterpillars are still difficult to find because they are growing so slowly. At URI’s orchard and blueberry patch, where we always seem to have a lot of winter moths, half of the tight cluster apple buds and blueberry flower buds contain winter moth caterpillars. This is well above the threshold of 1 caterpillar per 20 buds. Another blueberry patch in Washington County has 35% of blueberry buds with winter moth caterpillars. So winter moths can still be pesky, but they are pretty easy to control with insecticides. Next week should be an excellent time to spray for winter moth caterpillars, if needed.

If you want help assessing your winter moth population, or you want to talk about your fungicide program, or anything else, send an email or give me a call. 401-256-7438.