Powdery Mildew On Apples

The most likely cause of curling leaves on apple trees is powdery mildew. Since this isn’t a closeup shot it’s hard for us to be sure, but from this photo that’s what it appears to be. If it’s powdery mildew you should be seeing some white to grey spots or powdery-like coating on the leaves, either front or back. If you see that, you will know that this is the problem. Spraying with an organic fungicide might protect foliage that isn’t too far gone at this point, but your best option will be to clean up all the leaves that fall and dispose of them (not in your compost pile) and to begin spraying with an organic fungicide or the product of your choice next season BEFORE the plant has a problem. Use according to directions. If you don’t think that powdery mildew is to blame send us a few close-up shots that show both the top and bottom of two or three leaves that are in the process of curling and one of a leaf that’s pretty far gone.