Why are my leaves falling from my Crabapple Tree? Apple Scab Disease, A Common Issue for Homeowners in Grand Blanc

Apple scab, caused by the fungus Venturia inaequalis, is a widespread disease that affects not only apple trees but also crab apple trees, commonly found in residential properties. This disease is most prevalent in spring when wet, cool weather conditions promote fungal growth.

On crab apple trees, apple scab manifests as dark, olive-green lesions on the upper surface of the leaves. As the disease progresses, these lesions can turn brown or black, and the leaves may curl, distort, or drop prematurely. Severe infections can cause significant defoliation, weakening the tree and reducing its aesthetic value.

Typical symptoms of apple scab disease

• Fungal legions on the leaves

• Reduced flowering

• Leaves falling to the ground mid-summer

• Early season defoliation

• Secondary disorders and insect damage due to disease stress

• Branch die back and decline over time

To manage apple scab disease fungicide applications will need to be applied before the onset of infection in the Spring. As the tree continues to leaf out additional applications will be needed to protect expanding leaves. Typically, 3 total treatments offer great control for crabapples on residential properties.

Apple scab is not only a cosmetic issue but can also harm the long-term health of crab apple trees if left unmanaged.

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Source of the image:

The image of the diseased leaf is sourced from the University of Minnesota

https://extension.umn.edu/plant-diseases/apple-scab