Fungus hits city maple trees

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MARQUETTE - Some call them leopard patterns, other describe them as black spots.

But the commonly used name for the disease that has befallen Norway maples in the city of Marquette is called "tar spot" fungus.

"In the last five or six years, it has exploded on the Norway maple," said Paul Albert, arborist for the city of Marquette.

Albert has fielded many questions from Marquette residents about the disease - scientifically named rhytisma acerinum. It is a fungus that exclusively affects maples, Albert said.

"It has no detrimental effects whatsoever," he said. "It's no big deal, but it's unsightly."

Albert said the fungus only affects leaves and only spreads to other maple leaves. There is no way to control the spread because the fungus overwinters in the fallen leaves.

"In the spring when it rains, the spores are released and they land on leaves," Albert said. "The cycle continues."

The only way to try to prevent the spread of the fungus is to rake up all the leaves in the fall and hope all the neighbors do the same, Albert said.

"To get every leaf raked up is not feasible," he said, adding that no chemical treatment will solve the dilemma.

The cause of the fungus is not known, according to Albert, yet it is like any other tree or plant disease, "it's all part of the world we live in."

Albert has done extensive research on the fungus and has found that areas in Ontario and upstate New York have battled with the fungus for many years. Often the fungus comes on quickly and spreads widely but may also disappear just as quickly, he said.

"There is really no need to control it," he said. "It's not going to kill the tree."

Albert added that maples are one of the most popular types of shade tree - coming in 60 different varieties. Marquette is home to a vast number of maple trees, Albert said.

"This town is basically made up of maples," he said.