Issues with Maple Trees
The calls have been coming in and several homeowners are having issues with their maple trees. In each case, the homeowner says their maple tree had buds develop this spring, but now the leaves are falling off. The leaves that are falling off are shriveled up and have black spots on them. Given the time of year and our rainy spring, there are two possible things going on here.
The first thing that might be occurring if you are losing leaves is a fungus disease called anthracnose. Anthracnose can impact several species of trees including ash, maples, sycamore, and oaks. It is most noticeable in the bottom portion of the tree. The leaves will appear scorched with dark brown to black spots on them near the veins of the leaves. As time progresses, the leaves curl up and fall off the tree. It is most severe when cool, wet conditions prevail at the time when new leaves are emerging.
Anthracnose will not cause a tree to die. If your tree has anthracnose, it is best to just clean up the leaves that fall off the tree and dispose of them. Once you notice the anthracnose, it is too late to apply fungicides to control it. For more information about anthracnose, read Purdue publication, “Anthracnose of Shade Trees,” BP-9-W.
If anthracnose isn’t the reason behind the leaf loss, then the possible next reason is Maple Petiole Borer. When looking at the leaves that have fallen off, you will notice that the leaves are curled beyond the petiole. The petiole is the small stem that attaches the blade of the leaf to the tree. When you look closely, you will notice there is a hollow hole in the petiole. The leaf blade will typically still be green.
Maple Petiole Borer damage is often seen in May and June. Though many leaves can be lost in a single year, it will not kill a tree. There is no good way to know when a maple petiole borer infestation will occur. Therefore, you can’t really protect your trees. If your trees have this problem, it is best just to clean up the leaves that have fallen and maybe take the time to trim the branches of the trees a little (primarily the short sections where the leaves have fallen off because the borer will remain there for an additional 7-10 days after the leaves begin to fall).
As always, if you have any questions or would like information on any agriculture, horticulture, or natural resource topic, then please contact your local Purdue Extension Office at 448-9041 in Clay Co. or 829-5020 in Owen Co. or reach me directly at firstname.lastname@example.org. Purdue University is an equal opportunity/equal access/affirmative action institution.
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