Apple Scab

Apple scab is Pennsylvania's most important apple disease, attacking wild and cultivated apple and crabapple. Early season disease management is directed primarily at controlling apple scab.

Symptoms
The first infections often occur on the leaves surrounding flower buds. Dull, olive green areas visible on the undersides of leaves are the first evidence of the disease. As the lesions (infected areas) become older, they assume a definite outline as olive-green or brown circular spots. Leaves are susceptible to infection for about 5 days after they unfold. Severe early leaf infection can result in dwarfed, twisted leaves, which may drop later in the season.

For more information, please see this Penn State Tree Fruit Production Guide Web page.

Penn State Horticulture Department

For more information on this subject, Please visit the College of Agricultural Sciences Publications Web site.

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