Leaf Drop on Crabapples (Apple Scab)
Crabapple and apple leaf drop is associated with a fungus. It's
a serious problem on crabapples and apples when late Spring weather is humid.
This disease can cause the entire tree to defoliate. First, velvety, olive
green-to-gray spots develop on the leaves. Leaves with several spots then
yellow and drop from the tree. Infected fruits have spotted and cracked
skin, and mature irregularly.
To obtain adequate control of apple scab, a protective spray must be applied, starting as soon as bud growth begins in the Spring. Spray with Ortho's Multi-purpose Fungicide. Repeat this program five-to-eight times at intervals of seven-to-ten days. Make sure no spraying is done on the tree when it is in flower. Be sure to read the entire label and follow directions carefully for proper application. Collect and remove infected leaves from the ground throughout the season, especially in the Fall.
Damage from apple scab is not considered to be life-threatening to a well-established, healthy tree. However, if a tree is defoliated two or three years in a row, it becomes vulnerable to other pest problems. Thin the branches out to form an open canopy, which will improve air circulation so the leaves dry more quickly. Prune only in late Winter or early Spring, before growth starts.
When purchasing new trees, ask Bachman's nursery experts to recommend disease-resistant varieties.
For further information, read online our care sheet on "Diseases of Ornamental Crabapples".
Revised: 03/10/98
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