What's wrong with our maple?

Asked August 7, 2018, 11:02 AM EDT

I'm looking for advice on what to do for our maple tree. About a month ago the lower and inside leaves on our maple tree started to develop brown spots and fall off the tree. An arborist thought perhaps it has a fungal infection so he cut a branch looking for a blue stain on the cambium but there is no stain. He didn't have an answer. I noticed a neighbor's maple tree has a similar problem but to a much lesser extent than our tree. I've attached three pictures showing the bare lower branches of the tree, the upper surface of six leaves that fell over night, and the under surface of the same leaves. Thanks!

Howard County Maryland

3 Responses

It looks like your maple tree has symptoms of a fungal leaf spot disease, possibly phyllosticta. https://hgic.clemson.edu/factsheet/maple-diseases-insect-pests/
The excessively wet weather this year has been favorable for the development of a lot of fungal diseases. At this time in the season, there is nothing you can do. There is no cure for the symptoms you see. By this time of the year, trees have been storing up sufficient food reserves and leaf loss will not cause major harm to an otherwise healthy mature tree. Clean up the leaf matter under the tree to help reduce fungal inoculum. Monitor the tree early next season. If you see any branches in the crown that do not leaf out next spring, or if there is any visible damage to the trunk, that would be of greater concern. You have the option to consult with a certified arborist if you would like a professional to conduct an evaluation of the tree on site. You can find a certified arborist by using the "Find an Arborist" section of this website.http://www.treesaregood.org/


Thanks very much for the prompt reply. We'll keep the leaves cleaned up and watch it carefully.