Seal of Dane County County of Dane
Dane County Tree Board

Diseases & Insects

A host of various diseases and insects can cause concern for the health of Wisconsin's trees. Learn what the most prominent threats are currently, and discover a little about each one.


Oak Wilt
The fungus Ceratocystis fagacearum causes oak wilt, which results in leaves wilting and dropping off of an infected tree.

Dutch Elm Disease
Dutch elm disease is the most destructive disease of elms in North America.


Emerald Ash Borer (EAB)
The emerald ash borer is a devastating non-native insect that has killed millions of ash trees in the Eastern U.S.

Gypsy Moth
The gypsy moth was introduced in the United States from Europe in the mid 1800's and can make a tree more susceptible to attack by secondary organisms, such as the two-lined chestnut borer and shoestring root rot.

Asian Longhorn Beetle
The beetle attacks hardwood trees such as Norway, sugar, silver and red maple, horse chestnut, poplar, willow, elm, mulberry, and black locust.