Scab Disease

What is Scab Disease?

Apple Scab Disease, better known as Scab, is a potentially serious fungal disease of ornamental and fruit trees in the rose family. Trees that are most commonly and severely affected include Crabapple, Hawthorn, Mountain Ash, Apple and Pear. This disease is most severe in years with cool, wet weather.

What does Scab Disease look like?

Scab lesions (diseased areas) are often first noticed on leaves, where they most commonly occur on the upper leaf surface. Fruits are also very susceptible to infection. Lesions on both leaves and fruits are roughly circular with feathery edges, and have an olive green to black color. They can be as small as the size of a pinhead or as large as a 1 /5 inch in diameter. When disease is severe, lesions can merge and cover a large portion bf the leaf or fruit surface. Defoliation of the tree often follows.

How do I save a tree or shrub affected by Scab Disease? 

If your tree has a history of severe scab and the weather is cool and wet, then consider applying fungicide treatments. You will need to treat every 14-21 days from bud break until wet weather subsides. We recommend three treatments. Fertilizing will also help the tree fight off the fungus.

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