Ash Tree Diseases, Ash Tree Pests & Ash Tree Problems

There are several damaging ash tree diseases and pests. Some of the most common are:

Emerald Ash Borer – This invasive wood-boring beetle has killed millions of ash trees in the United States by attacking the tree’s nutrient carrying vessels.  Look for S-shaped galleries on the underside of the bark and D-shaped exit holes. Read more about the emerald ash borer.

Anthracnose – This disease results in extensive defoliation, shoot dieback, and twig death of ash trees. Often confused with frost damage, signs of anthracnose include brown areas on ash tree leaves, canker on the trunk and main branches, and purplish-brown areas along the veins of the leaves.

Ash Yellows – This disease affects mostly white and green ash trees.  It is characterized by a loss of vigor over the years. Leaves may start to yellow and develop early fall color. The ash tree may lose leaves and cankers may start to form on the trunk and branches, causing dieback.

Verticullium Wilt – This infection results in cankers and dieback.

The Emerald ash boer (EAB) is a non-native insect pest that infests and kills all species of ash trees in North America. It was first discovered in southeastern Michigan in 2002 and EAB has since been found in 27 additional states and 2 Canadian providences. The EAB has killed tens of millions of ash trees in Michigan alone, as well as hundreds of millions of additional trees in the other infested states and providences.