Apple Scab
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Apple Scab
 Apple scab is one of the most serious diseases of apple and ornamental crabapple. Disease development is favored by wet, cool weather that generally occurs in spring and early summer. Both leaves and fruit can be affected. Infected leaves may drop resulting in unsightly trees, with poor fruit production. This early defoliation may weaken trees and make them more susceptible to winter injury or other pests. Infected fruits are blemished and often severely deformed. Infected fruits may also drop early.Susceptible Plants- Apple and Ornamental Crabapple Symptoms- Apple scab is one of the most serious diseases of apple and ornamental crabapple. Disease development is favored by wet, cool weather that generally occurs in spring and early summer. Both leaves and fruit can be affected. Infected leaves may drop resulting in unsightly trees, with poor fruit production. This early defoliation may weaken trees and make them more susceptible to winter injury or other pests. Infected fruits are blemished and often severely deformed. Infected fruits may also drop early. Fruit symptoms are similar to those found on leaves. The margins of the spots, however, are more distinct on the fruit. The lesions darken with age and become black and "scabby." Scabs are unsightly, but are only skin deep. Badly scabbed fruit becomes deformed and may fall before reaching good size. Prevention and Control- Rake and destroy fallen leaves. This will reduce the number of spores that can start the disease cycle the next year. In autumn water fallen leaves on the ground with high nitrogen liquid such as (nettle brew, manure tea) as this will help kill spores and decompose leaves. Mow the ground below the trees to shred leaves and speed decomposition or collect leaves and compost them. Cut out and burn the diseased twigs. Prune apple trees to maintain good air circulation.
The use of resistant or scab immune varieties is the ideal method for controlling apple scab. Currently there are several apple varieties that are totally resistant to scab. Backyard growers are strongly encouraged to consider using these resistant varieties in order to reduce or eliminate the need for fungicide applications around the home.
However if you already have established cultivars with apple scap; garden fungicides
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