Jeff Stachler, OSU Extensioneer in Auglaize County sent the following message this past Tuesday on June 6:
“A maple tree in the front of a home yard has leaves with the symptoms you see in the photos. Veins and leaf tips are black with yellow and brown colors below the black. Is there anything that can be done or should be done?” He also sent the tell-tale photo above, showing “water-soaked” darkish lesions along leaf veins.
Right on time. Last June 5, I took a picture of a neighbor’s red maple in Doyletown in northeast Ohio of the same problem: maple anthracnose. As noted then, homeowners do become quite concerned about this fungal disease in wet springs, worried that “all the leaves are fallin’” from a beloved maple tree. We are all familiar with this sky-is-falling observation, that in most cases turns out to be a bit overstated.
At most, probably 1% of the leaves or less will have fallen and maybe 5% of leaves show symptoms of maple anthracnose - though it seems like more. The affected leaves are on the lower portion of the plant. Why on the lower leaves? Because there is poorer air movement there and the maple anthracnose fungus thrives under these conditions.
Maple anthracnose occurs on a number of maple species, including red maple (Acer rubrum), silver maple (Acer saccharinum), and in my backyard this summer, on our native striped maple (Acer pensylvanicum).
Not to worry, as the temperatures rise with summer this disease is not destined to become worse and worse and typically this disease is of minor relevance to plant health. We certainly had plenty of cool, wet days this spring during leaf emergence – the key Disease Triangle “environment conducive to disease” conditions for maple anthracnose, but we, and the maples are moving on.