Answer: What you describe sounds more like damage from insect feeding than from a disease. Leafhoppers and mites can feed on leaf surfaces and the damage to the leaf results in an off-color: usually a rust color. When feeding insects rasp or scrape away the upper surface of a leaf it can turn a rusty color. For a positive diagnosis, take a few of the affected leaves to your local cooperative extension office. (Johnston County Cooperative Extension, 2736 NC 210 Hwy, Smithfield, NC 27577). Staff there can diagnose the problem and suggest control remedies. Best wishes with your apple tree.
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