How to identify and prevent Apple Scab Disease

Northeast Ohio is no stranger to fungal tree diseases like Oak Wilt or Dutch Elm. Few have proven more serious and unsightly than Apple Scab disease.

Apple Scab affects both ornamental (crabapple) and apple trees. Crabapple trees are most common in suburban areas and, when infected, will defoliate – dropping leaves and rotten crabapples all over your property.

Fortunately, the infection is easy to spot and there are proven methods of treatment. Here’s how you can spot the disease in time to limit its damage:


  • Apple Scab appears in early spring when the tree’s leaves begin to develop dark, velvety spots. This fungus produces additional spores that spread throughout the tree as the rainy season arrives, infecting other leaves, fruits and flowers.

  • In early summer, the tree will start to lose its leaves and become unsightly. The fungus that’s attached to fallen leaves survives the winter, releasing millions of spores into the air the following spring.


  • While Apple Scab can cause unsightly damage to your crabapple trees it rarely kills them, especially if you take precautions. Raking and disposing of the leaves that fall from infected trees is the simplest way to arrest the disease’s spread.


  • The most common and effective treatment for Apple Scab is seasonal spraying. A properly licensed tree service company, using the right fungicides, can spray and inject infected trees in the early spring, before the first leaf tips appear. Fungicides should be sprayed three times and injected once before the flowers drop their petals.

Budding season is the best time to assess and treat your trees. To learn more, contact Ripley Tree Service, an independent family business with three certified arborists on staff, serving Northeast Ohio since 2001.

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