Maple Trees Losing Their Leaves

Kalamazoo, MI - Does it seem like autumn under your maple tree with the exception that the leaves are green?

Last week I began to notice many leaves falling under maple trees. Upon closer observation, the leaves had only half of the stem (petiole). This is caused by tiny larvae called maple petiole borers.

The female slices a small slit into the plant stem and inserts an egg. The egg hatches into a small larva that feeds inside the petiole, weakening it and causing it to break off and fall to the ground. There is only one generation each year in Michigan and it usually only lasts one to two weeks. Maple trees have a very dense canopy and most trees can sustain the leaf loss without harm to the tree.

We recommend no chemical application for maple petiole borers since there are many natural biological control agents that keep this pest in check. The recommendation is to clear the leaves by either raking or mulching while mowing the lawn.

The actual borer remains in the portion of the petiole that is still attached to the tree where it is vulnerable to predators.

For more information about MSU Extension Horticulture programs, call Linda Whitlock, Consumer Horticulture Coordinator at the Kalamazoo County MSU Extension office, (269) 383-8815, or visit our web site at www.kalcounty.com/msue

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MSU Extension is an Affirmative-Action Equal-Opportunity Institution. Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, marital status, or family status.

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