Common Tree Diseases & Pests

Banded Elm Bark Beetle

The Banded Elm Bark Beetle has been detected in Michigan.

Blue Spruce Diseases

Colorado blue spruce is a popular tree species planted for windbreaks, screens and general landscape purposes. Unfortunately, blue spruce is susceptible to several diseases and insect pests. To learn more about these diseases and how to control them view the Spruce Problems handout prepared by the Conservation District.

Diplodia Tip Blight

The fungus Diplodia pinea can cause serious damage to Austrian, ponderosa, red, Scots, mugo, jack, and white pine. For more information go here:

Eastern Tent Caterpillar

The eastern tent caterpillar is often mistaken for the gypsy moth. Though they are similar in appearance, they differ in habits. For more information go here:

Emerald Ash Borer

European Pine Sawfly

This sawfly can severely defoliate jack, red & Scotch pine primarily, but will feed on other pines as well. Here is more information:

Forest Tent Caterpillar

The forest tent caterpillar is a native species found throughout hardwood forests of North America. It feeds on the leaves of many trees, but in Michigan outbreaks occur in aspen, birch, basswood, sugar maple and oak stands. More information is available here:

Gypsy Moth

The gypsy moth has been a primary defoliator of hardwoods in the Northeastern United States since its introduction in 1869. For additional information, follow these links:

Hemlock Woolly Adelgid

THe Hemlock Woolly Adelgid has been discovered in several Michigan locations and the Department of Agriculture and Rural Development has instituted a quarantine related to this pest.

Oak Wilt

This is an aggressive disease that affects many species of oak. It is one of the most serious tree diseases in the eastern United States, killing thousands of oaks each year in forests, woodlots, and home landscapes. Learn more about Oak Wilt at:

Sirex Woodwasp

This insect attacks Scotch and Austrian pines almost exclusively. More information is available at:

Spruce Decline, Diseases & Pests

Spruce trees are experiencing decline throughout Michigan from a variety of maladies—including several needle cast and canker diseases; gall aphids and spider mites. To learn more about what may be affecting your spruce trees, view the Spruce Problems handout prepared by the Conservation District.

Thousand Cankers Disease

This disease has the potential in impact black walnut trees in Michigan.

White Pine Shoot Borer (Eastern Pineshoot Borer)

Other Insect & Disease information

Washtenaw County Conservation District
7203 Jackson Rd.
Ann Arbor, MI 48103-9506 [Map]
Phone: (734) 761-6721 x 5
Fax: (734) 662-1686
Open Mon. - Fri., 8 a.m. - 4:30 p.m.