The scab fungus overwinters in apples leaves on the ground. Properly prune the tree canopy for better ventilation and faster drying of leaves. When planting crabapples, select varieties that are resistant to scab. Fungicides can be used to protect scab susceptible crabapples. Sprays need to be applied when growth first appears and repeated at 7 to 10 days intervals.
Thorough coverage is essential.
Fungicides for scab control include Daconil 2787, Cleary's 3336, Funginex, or products that contain captan, maneb, or mancozeb. Carefully read the manufacturer's label. Prepared by Paula Flynn , Department of Plant Pathology Iowa State University , Ames, Iowa. This information subject to a usage policy .