Answer: Yellowing leaves does not necessarily indicate Apple scab. Symptoms of apple scab include brown to olive-green, roughly circular, fuzzy spots which often originate along the veins of the leaves. In time, spots become black and velvety and develop fringed margins. Finally, leaves yellow and drop. Very susceptible cultivars may show a very rapid blackening and curling of leaf tissue. In a ?bad? scab year it is
not unusual for trees to suffer near complete defoliation by the end of June. Small, round, dark areas that become corky frequently appear on fruits.
Yellow spots on the leaves might indicate a disease called cedar apple rust. Without knowing which might be causing the problem, it's difficult to suggest a control remedy.
For positive diagnosis, take some of the affect leaves to your local cooperative extension office. Helpful folks there can suggest controls.
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