I've noticed a lot of brown spots on oak trees and was wondering if there were a fungus or a disease going around?
Aphids feeding on leaves sometimes make brown blotches, according to Jennifer Smith, horticulture agent with the Douglas County Extension Service. Aphids are small-bodied insects like lice. There also is a fungus called anthracnose that can cause brown spots. Both problems should go away when the humidity decreases, Smith said.