Apple Scab
Affected Plants
Apple Scab is a fungal disease that attacks Apple, Crabapple, Quince, and Pyracantha.Signs and Symptoms
Apple scab can be very severe causing leaf loss, reduced vigor, and reduced flowering.The most common symptom of apple scab is olive-green spots on the leaves. These spots enlarge, darken and become velvety over time. Spots may be raised, giving the leaf a puckered appearance. A leaf with several spots eventually turns yellow and drops from the plant prematurely. Heavily infected trees may be defoliated by mid-summer. If scab is severe for several successive years, the vigor of the tree is seriously diminished. The plant may die from several bouts with severe scab.
Disease Cycle
The fungus, Venuria inaequalis, over-winters in leaves on the ground. When the plants begin spring growth, the fungus produces spores on the fallen leaves. These spores become airborne, initiating spring infections. An hour after the leaves on the ground become wet, spores are released into the air spreading from leaf to leaf by wind and splashing rain.Control and Management
Disease management involves selecting disease resistant varieties when planting, cultural practices, and chemical control.Disease Resistant Varieties: Contact your local county extension office, nursery, or garden center for plant varieties resistant to apple scab.
Cultural Practices: Cleaning up and disposing of fallen leaves can reduce the amount of spores produced in the immediate vicinity of the plant. However, spores can blow in from outside the sanitized areas.
Chemical Control: The most effective time to control apple scab is with plant protection products prior to infection. Three well-timed applications will limit scab development and keep leaves from falling; however, no control is one hundred percent effective.
Contact your RYAN certified arborist to learn more about our preventative fungicide program to help control this disease.