Apple Trees – Orange-Yellow Spots On Leaves

Q: We just purchased a new house with a couple of apple trees on the property. The leaves have lots of little orange-yellow spots on them.

A: It’s likely cedar-apple rust. Your trees may start dropping leaves soon. Red cedar trees are alternate hosts for this disease. The rust spores can affect apples within a half-mile of an infected cedar tree. Spraying with myclobutanil (Immunox) at labeled intervals will partially control the disease. You can help break the disease life cycle by raking and removing all apple leaves after they fall and by examining all red cedar trees in your neighborhood for the brown walnut-sized disease galls, which should be destroyed.