MUSKEGON, Mich. - The City of Muskegon closed a disc golf course at McGraft Park because of oak wilt, a fungus that kills trees.

There's concern that the discs make the trees more susceptible to the disease.

13 On Your Side Verified: Does disc golf put trees at risk of oak wilt?

Father and son Tim and Aaron Hoeker took a trip to McGraft Park hoping to play disc golf.

“We walked up to the t-box and someone walking by said they took the baskets down because of oak wilt,” Aaron Hoeker said.

Scott Van Wyk, an arborist with Bartlett Tree Experts said April through September is when oak wilt most easily spreads.

“It’s a disease that attacks the sap system of oak trees and causes them—in most cases—to die,” Van Wyk said.

It spreads by insects through tree wounds and broken limbs, or roots coming in contact.

“Beetles will feed on the sap that’s produced and if they come from an infected tree to a healthy tree, they can then transmit the disease,” Van Wyk said.

The unassuming sport can be the reason oak wilt gets introduced to a new area.

“The ones that you throw a long way they have these sharp edges and they take the bark out.”

Tim Hoeker said the discs are not frisbees, and they are hard plastic.

“They could throw the disc and hit the tree and that wound doesn't have to be that big. It just has to be big enough to create a little sap flow,” Van Wyk said. “The beetles will be able to scent that and they will fly to that and then spread the disease.”

The beetle is in Muskegon county.

“We do have cases of oak wilt in Muskegon county,” said Kevin Santos, the Muskegon forestry supervisor. “We don't have any confirmed cases of oak wilt at McGraft Park.”

The city is taking precautions since the park has hundreds of oaks.

“What were trying to do is minimize the wounding of the trees basically so that we can try and reduce that risk,” Santos said.

So we can Verify: Disc golf does in fact put trees at risk of oak wilt.

Santos said Muskegon is working to find a way to safely re-open the course.

A Whitehall-area disc golf course is also closed for the same reason.

To see more of 13 On Your Side's Verify stories, check them out here.

Make it easy to keep up to date with more stories like this. Download the WZZM 13 app now.

Have a news tip? Email news@wzzm13.com, visit our Facebook page or Twitter.