Maple Tree Blight No Cause for Concern, Expert Says

A fungal disease tainting maple tree leaves in the Port Washington area isn’t any cause for concern, a local expert says.

Dan O'Neil, agriculture agent with the University of Wisconsin Extension in Port, said the the disease is actually one of the most common fungi that land on maples, and called it mostly an "ornamental" problem.

"Most of the maple trees, by the time they are big, they are pretty strong and tough," O'Neil said. "A drought condition would be worse than this tar spot."

The blight, known as "tar spot," affects maples in other parts of the state and country, according to Sharon Morrisey, consumer horticulture agent with the Milwaukee County University of Wisconsin Extension.

But O'Neil said the Port Washington area provides an excellent climate for the disease compared to elsewhere.

"We just have a perfect a place (in Port), because (the disease) lives in the leaves, it likes moisture … we have a lot of spring and fall moisture compared to other areas," O'Neil said. "It loves it here."

Morrisey said the disease isn't anything to worry about. The fungal infection doesn't affect the overall health of maple trees, just its appearance. The disease triggered by two different types of fungus causes leaves to turn brown and develop tar-like round spots. The disease also causes leaves to fall earlier than usual, Morrisey said.

Morrisey added the best way to control the spread of "tar spot" is to rake up fallen leaves immediately and either bury or throw them into a compost pile.

“It'll help stop the spread of the infection,” Morrisey said.