Cooperative Extension: Maine Wild Blueberries

Monilinia infections April 26, 2022

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Most fields have susceptible bud stages with over 30% F2. Most fields in the Midcoast are moving into F3 and F4 flower buds. Downeast fields are mostly over 40% F2 and some have about half their buds at F3. There are some later fields along the east coast or up near Hwy 9 (Airline) which are still mostly in F1 and moving into F2. Please check your fields. We have seen mummy berry cups in most fields in both midcoast and downeast so I suspect mummy berry cups are active in most areas of blueberries in Maine.

A Monilinia infection period is likely to have occurred throughout blueberry growing areas with the rain that started yesterday, April 26th afternoon or evening, through today, April 27th. If you applied fungicides after April 16th (10 days) or April 19th (7days) then your plants were probably protected during this rain event. Most fungicides are effective from 7 to 10 days after application depending upon the particular fungicide and how much rain they have been exposed to. The rain today and through until the weekend will likely produce more infection periods.