GRAND RAPIDS, Mich. (WOOD) — Do you have oak trees on your property? The Michigan Department of Natural Resources is encouraging you to include your tree trimming in your final round of yardwork before winter hits.

Why? To prevent the spread of oak wilt.

Oak wilt is a fungal disease. When a tree is infected, it reacts by producing “tyloses” that cut off the flow of water and nutrients to other parts of the tree. Without those nutrients, branches start to wilt, and with no leaves to soak up sunlight and convert it to energy, the tree dies.

The fungus is typically spread by sap beetles that carry it from tree to tree, but it can also spread through root grafts.

The DNR encourages people to trim oak trees in colder months because the beetles are packing in for the season.

“Beetles that can carry the disease from tree to tree are not very active right now, and the trees are not vulnerable to infection. The beetles are attracted to fresh bark damage or wounds where tree limbs have been removed,” DNR forest health specialist Simeon Wright said in a statement.

A tall oak tree is infected with oak wilt. The right side still looks relatively healthy, but the branches on the left side have either dropped their leaves completely, or are still holding on to brown, dying leaves.

Oak wilt was first identified in Michigan in the 1940s and is now considered widespread across the Lower Peninsula and the Wisconsin border of the Upper Peninsula. Red oaks — oak species that notably have leaves with pointed tips — are more susceptible to oak wilt and die faster. White oaks — with rounded edges on their leaves — are less susceptible.

“Affected trees will suddenly wilt from the top down, rapidly dropping leaves, which can be brown or a combination of both colors,” the DNR stated.

If you cut down or take wood from a tree that may have had oak wilt, the DNR recommends covering it with a plastic tarp and burying the tarp’s edges underground, cutting off access for beetles to pick up the fungus. Leave the tarp sealed for at least six months, preferably up to a year, to kill the fungus and prevent spreading it to other trees.

If you suspect oak wilt, you are encouraged to contact a DNR specialist.