Question: I have some of the old-fashioned Chinese photinias. I like them even better than redtip, but their new leaves seem to roll so badly in the spring. What causes that? Is it a mold? I see white dust on the leaves.

Answer: Yes. That’s powdery mildew. Control it with a fungicide, and do what you can to improve air circulation around the plants. Chinese photinias, rarely sold in the nursery trade, are outstanding large screening shrubs (to 20 feet tall and 14 feet wide).