From Kerik Cox, associate professor, Department of Plant Pathology and Plant-Microbe Biology.
The rains aren’t letting up and the cool weather is persisting. It’s a perfect storm for anthracnose and botrytis on near mature strawberries and raspberries in bloom. When there has not been rain, it’s not been warm enough to really dry things out.
In this weather, it’s important to protect your fruit or flowers. Switch, Elevate, and Pristine would all be excellent choices to use for fruit protection as they have 0 Days to Harvest Intervals. When there’s a break in the rain, make sure to protect your fruit and flowers from botrytis and anthracnose. If conditions continue consider re-protecting in 10 days or after 2 inches of rain.
Click on thumbnails for larger views.
Left: Brown sunken anthracnose fruit rot lesions (bottom left) and gray mold/botrytis fruit rot (top right) on ripe and ripening strawberries.
Center: Gray mold infected red raspberry.
Right: Raspberry (and strawberry) blossoms should be protected from gray mold infection beginning at 10% bloom. A second protective application should be applied at full bloom. Additional applications may be needed as fruit ripens when conditions are favorable for fruit rot development.