Fruit tree scab is characterized by a large number of small raised marks or scab on the fruit. The leaves can also show similar brown, scale- and scab-like lesions. In cases of significant infection, the fruit will not develop normally and the tree will undergo early leaf drop. The scab is caused by a fungus that attacks the surfaces of the fruit and leaves. It is encouraged by damp conditions caused by a wet spring period or the use of over-head irrigation and sprinklers.
To control scab on trees, spray the tree with Captan Fungicide. It should be applied in the early spring before the new spring growth starts and then again shortly after the petals have dropped from the fruit blossoms. A third spraying can be applied shortly after the fruit has formed. To help reduce the spread and growth of scab on fruit, never use a above-ground sprinkler on a fruit tree as the water will help spread the scab. When watering a fruit tree, always use a soaker (or drip) hose on the ground near the tree’s drip-line.