planted 4 yrs ago. seems healthy. 15 - 20 feet tall. Has fall webworm on a few branches. In the last week some leaves turned yellow and dropped not necessarily from the branches housing fall webworm. leaves have brown spot with green halo. See photo of leaves Can you diagnose from photo? Thanks
Hi - This looks like some early fall coloration due to stress conditions such as hot weather. Several types of trees are showing stress symptoms at this time of year, but it is nothing to be too concerned about. By this time in the season, trees have stored enough carbohydrates (food reserves) to be able to put out healthy new growth next season. Just give the tree normal good care. Water during periods of drought and avoid excessive mulching. Mulch should be no more than 2-3" deep and keep it a few inches away from the trunk.