Prune your trees early this year to prevent infection, DNR warns

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For the health of your trees, Department of Natural Resources officials are suggesting you get your oak pruning done by mid-March.

Iowa DNR officials are trying to prevent the spread of oak wilt, which has been in Iowa for many years.

With warm temperatures leading the way to an early spring, DNR officials say “the growing season may be getting a head start.”  That means trees, wounded from pruning, are more susceptible to catching disease.

“The best way to prevent the spread of oak wilt is to not prune any oak tree during its growing season” says Tivon Feeley DNR forest health program leader.

Trees can catch oak wilt, which is a fungus, when they have open wounds, like after pruning.  Beetles can spread the infection by landing on the open wound of a diseased tree and then landing on the open wound of a healthy tree.  The infection can also be spread through root grafts between oak trees that are near each other.

Oak wilt can kill some oak trees within months (red, black, and pin oak mostly) and other oak trees after a number of years (white and bur oak), the DNR said.

Diseased trees will show signs of infection, like leaves with a bronzed-brown outer edge, defoliation at the top, or if the tree is dropping leaves that are still partially green.

You can protect a wounded tree from catching the fungus by treating its open wounds.  Click here to see how to identify, prevent and control oak wilt.