Terribly Looking Leaves on Maple Trees

Maple leaf browning and spotting


If you have been noticing the leaves on your maple tree looking really bad, you are not alone.  Dark spots, browning leaves, and premature leaf drop have been widespread this summer on Norway maple trees.  Fungi disease is the cause of these problems.  Widespread rain in the spring for the previous few springs have caused an abundance of tar spot fungi, powdery mildew, septoria leaf blight, and anthracnose fungi.  These fungi often work in concert with each other and infect the leaf

Tar spot on maple
Tar spot fungus on Norway maple

surfaces in the spring and by late summer symptoms become readily apparent.  Even though the tree may look terrible, fortunately the unsightly problem is usually not serious for the tree.  By late summer the leaves have done most of their work for the season and the tree can usually cope with this loss.  In general fungi problems are most severe in moist areas that do not dry out quickly.  This means that shady areas low on the tree are most suseptible to problems.


Control of maple leaf fungi can be achieved using a multifaceted approach.  Pruning to create better air flow thru the tree will allow it to dry out faster.  Good clean up of fallen leaves in autumn will lessen the amount of fungi spores allowed to reinfect the tree in spring.  In severe cases of maple leaf fungi diseases, foliar fungicide sprays can be performed in the spring as a preventative treatment.


Newly transplanted trees, trees weakened by stress, or trees that have been repeated infected are particularly sensitive. In such cases, chemical controls can be beneficial and may be recommended.  If you have questions or wonder if control steps are necessary on your trees contact Hoppe Tree Service to talk with a certified arborist.


August Hoppe

Certified Arborist WI-0477A

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