Beech leaf disease, an invasive species that attacks vulnerable trees, found in Michigan

DETROIT – Beech leaf disease has been found in Michigan, making it the ninth state across the country with confirmed cases of the invasive species.

Following its addition to Michigan's invasive species watch list last year, beech leaf disease has been found in St. Clair County, according to the Michigan departments of Natural Resources and Agriculture and Rural Development  (DNR).

Michigan is now one of nine U.S. states with confirmed cases, according to the Michigan DNR. Beech leaf disease was first detected in Ohio in 2012. Following discoveries in other parts of North America lead to annual surveys across the eastern U.S. starting in 2020.

In addition to Michigan and Ohio, beech leaf disease has been detected in New York, Massachusetts, Rhode Island, Pennsylvania, New Jersey, Connecticut and Maine in recent years. 

Beech leaf disease harms the leaf tissue of beech trees – which are important to forests and wildlife nationwide. According to the Michigan DNR, for example, there are 37 million American beech trees in the state.

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Leaf damage can weaken trees, causing fatal consequences within six to 10 years, the Michigan DNR said.

"We don’t yet know all the ways the disease might be spread, and currently there are no known treatments to protect trees or reduce disease impacts," said Simeon Wright, forest health specialist for Michigan's DNR.

Michigan beech trees have already been made vulnerable by beech bark disease, and with no remedy for either sickness, the trees could face a deadly outcome in years to come, Michigan's DNR said.

Using the Midwest Invasive Species Information Network, residents of St. Clair County reported suspicions of a beech leaf disease outbreak after spotting unusual looking leaves on their land.

The report prompted Michigan's DNR to send forest health staff to visit the area and retrieve samples for testing to be done by the Michigan State University Forest Pathology Laboratory.

The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service confirmed the results and the test for beech leaf disease was positive.

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“Though beech leaf disease was detected this spring, the condition of the leaves and number of trees affected at this location suggest the disease has been there for more than a year,” Wright said. “Because symptoms are slow to emerge, it is difficult to detect the disease before it is established.”

For residents on the lookout, the symptoms of beech leaf disease include "damaged leaf tissue, dead buds and darkened, thick tissue bands between leaf veins," Michigan's DNR said.

As time passes, distortion and curling of leaves may occur, causing them to become dry or yellow.

On heavily infested trees, major leaf loss may occur at the start of summer, but Michigan's DNR said that there is not enough information on beech leaf disease yet to know the full long-term effects.

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"State agencies are working with the U.S. Forest Service, several other states, Ontario and Michigan State University to better understand the disease and the potential effects it will have in Michigan’s forests," Wright said.

Officials are encouraging Michigan landowners to be on the lookout for beech leaf disease, and take photos if there are any sign of symptoms. Sightings can be reported to the state's DNR Forest Health Division or the Midwest Invasive Species Information Network.

Contributing: Wyatte Grantham-Philips, USA TODAY.

This article originally appeared on Detroit Free Press: Beech leaf disease found in Michigan, 9th state with invasive species