Question From: Alamosa, Colorado, United States
Q: I have a white powder on my crab apple tree where the branches have been trimmed in the past and it has spread to our neighbors tree also. It is spreading rapidly.
The white powder is powdery mildew. Here's a link to information about the disease and control: http://extension.psu.edu/plants/tree-fruit/diseases/apple-diseases/powdery-mildew . Best And Happy Yardening, Nancy