Apple Scab (Venturia inaequalis)

​Apple Scab is one of the most prevalent and aesthetically damaging fungal diseases affecting apple and flowering crabapple trees worldwide. While it rarely kills the tree outright, a severe infection can lead to total fruit loss and significant defoliation, weakening the tree over time.

​Symptoms to Watch For -
​On Leaves -
​Early infection: Small, olive-green to brown velvety spots appear on the undersides of leaves.
​Progression: Spots become more distinct, circular, and turn a dark "scabby" brown or black.
​Result: Heavily infected leaves turn yellow and drop prematurely, often by mid-summer.
​On Fruit -
​Appearance: Distinct brown, corky, or "scabby" lesions develop on the skin.
​Growth Issues: If infected early, the fruit may become distorted, cracked, or stunted.
​Edibility: While the scabs are unsightly, the fruit remains edible if the spots are peeled away, though the storage life of the fruit is greatly reduced.

​The Disease Cycle -
​Apple scab thrives in cool, wet spring weather.
​Overwintering: The fungus survives the winter in fallen leaf litter on the ground.
​Primary Infection: In spring, rain triggers the release of spores (ascospores), which are carried by wind and rain droplets to new green tissue.
​Secondary Infection: Once established, the fungus produces a different type of spore (conidia) that spreads the disease to neighboring leaves and fruit throughout the growing season.
​Management and Prevention

​An integrated approach is the most effective way to keep your trees healthy.