Apple scab overwinters in infected leaves on the orchard floor. Spores from the dead leaves are produced in the spring and can cause primary infection of fruit. The Michigan growing season was wet last year. As a result, apple growers had a tougher-than-usual time controlling scab. But the weather was the lesser of their problems. The type of fungicide they have been relying on for the last decade is losing its punch. Venturia inaequalis, the fungus that causes scab infections, is rapidly developing resistance to the strobilurin fungicides in Michigan. Michigan State University plant pathologist Dr. George Sundin discussed scab […]