Apple Scab Disease: Treatment and Prevention

Apple Scab Disease Symptoms

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“I have several apple trees, which usually have had good crops. But in recent years there weren’t as many spring blossoms, leaves were dropping in summer and no leaves remained by fall. What’s going on?” asks Birds & Blooms reader James Elliston of Delton, Michigan.

Gardening expert Melinda Myers says, “It sounds as if your trees are suffering from apple scab. This fungal disease is a common problem on apple, crabapple, hawthorn, mountain ash and pear trees, though some newer apple varieties have been bred to be resistant to this disease.

Warm, rainy spring and summer weather creates the ideal conditions for this disease. You’ll first notice olive-green to black spots on the leaves. These may merge, cover the leaves and cause them to drop. Repeated leaf loss early in the season can stress the tree, making it more susceptible to other problems and decreased fruit production.

Learn out other common tree diseases (and what to do about them).

How to Prevent Apple Scab Disease

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Melinda says, “Reduce potential future infections by doing fall cleanup of infected leaves. Proper pruning—opening up the canopy to allow the leaves to dry more quickly—reduces the risk of this disease while boosting fruit production. Replacing scab-susceptible tree varieties with more resistant ones is another long-term solution.

Consider adding a few to your landscape if space allows. Once the new plants reach fruiting size, you can remove the other trees.”

Here’s how to identify emerald ash borer damage.

Apple Scab Disease Treatment

Melinda adds, “Finally, some fruit growers opt to treat apple scab with a fungicide. This must be done before the disease starts and throughout the season, to protect the plant from infection. Always make sure to read and follow all label directions if you choose to use a chemical control.”

Next, learn how to get rid of powdery mildew.

About the Expert

Melinda Myers is the official gardening expert for Birds & Blooms. She is a TV/radio host, author and columnist who has written more than 20 gardening books. Melinda earned a master’s degree in horticulture from the University of Wisconsin-Madison.

Sources

• University of Wisconsin-Madison Division of Extension – Apple Scab