The frequent rains this spring have created ideal conditions for the development of apple scab on crabapples.
Apple scab is a serious problem on susceptible crabapple varieties.
Scab appears on leaves as roughly circular, velvety, olive-green spots on both the upper and lower leaf surfaces. The spots eventually turn dark-green to brown. Margins of these spots are feathery rather than distinct. Heavily infected leaves may curl up, become distorted in shape, turn yellow and fall off. Highly susceptible crabapple varieties may lose almost all their leaves by midsummer.