Seeing Bare Norway Maples Already? Fungal Diseases Are Mostly to Blame

08/18/2026

SYRACUSE, NY — Aug. 18, 2026 — A hallmark of Central New York is the fall foliage. This year, however, the Norway maples seem to have got a jump start on autumn, but not in a good way.

Most Norway maples in the Central New York landscape, especially the purple-leaved cultivars such as Crimson King and Queen, have few if any functional leaves as they have withered into a crumbly mass.

Norway maples, an invasive tree species, often have this issue, according to Distinguished Teaching Professor Donald Leopold at the SUNY College of Environmental Science and Forestry (ESF), primarily because of fungal diseases called anthracnose, which is promoted by cool, moist springs, and tar spot which appears to be developing earlier in the growing season more recently. Additional factors include the dry periods this summer, salt stress along city streets, and the general decline of trees that are relatively old for Norway maples.

“While the trees are unattractive, they will recover,” said Leopold, “as they have in past years. A few years ago this issue happened earlier during the growing season and many Norway maples were completely defoliated by now. All of these that I have watched have recovered.”

There are about 150 maple species in the world, and the Norway maple is especially susceptible to anthracnose and tar spot diseases. “Some red maples, including the one in my yard, show some signs of anthracnose, but it isn't causing leaves to drop,” said Leopold. The only other maple that often shows tar spot disease is silver maple and its hybrid with red maple.

When it comes to Norway maples, Leopold doesn’t mince words about how to prevent this problem. The best remedy is to get rid of all the Norway maples, said Leopold. In some communities, Norway maples aren't even allowed to be planted, and the tree is listed as "regulated" in the New York State Department of Environmental Conservation (DEC) under its Prohibited and Regulated Invasive Plants regulations.

“This tree is among the most invasive woody species in the Northeast, has many liabilities, isn't particularly attractive given its problems, and is impossible to maintain a lawn or meadow beneath,” he said. “It has no redeeming qualities other than a dense shade when the leaves stay on the tree through October as they should.”

There are many other species of maple and of many other genera (types) that are better shade trees, Leopold said.

The proliferation of Norway maples also impacts sugar maples, from which we get sap to make maple syrup and other products.

“The Norway maples are preventing the regeneration of sugar maples in woodlands throughout the Northeast,” said Leopold, “as if the deer aren't a sufficiently bad problem already for the sugar maples.”

About SUNY ESF

The SUNY College of Environmental Science and Forestry (ESF) is dedicated to the study of the environment, developing renewable technologies, and building a sustainable and resilient future through design, policy, and management of the environment and natural resources. Members of the College community share a passion for protecting the health of the planet and a deep commitment to the rigorous application of science to improve the way humans interact with the world. The College offers academic programs ranging from the associate of applied science to the Doctor of Philosophy. ESF students live, study and do research on the main campus in Syracuse, N.Y., and on 25,000 acres of field stations in a variety of ecosystems across the state.