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Forest health
Forest health
Protecting Michigan's forests
Protecting the health of Michigan's forests is a challenging task that requires collaboration. Our forest health professionals work with other state and federal agencies and universities to prevent, evaluate and manage the occurrence and impacts of both native and exotic forest insects and diseases. Email the forest health team with questions about pests and diseases.
Annual Forest Health Highlights
Read the latest Forest Health Highlights Report.
Plant and pest quarantines
See quarantines issued by the Department of Agriculture and Rural Development.
View and report Heterobasidion root disease locations
View and enter a report into our interactive map.
View and report oak wilt locations
Seeing spots? It could be spongy moth.
The sight of red-and-blue spotted caterpillars munching on backyard trees is a sure sign of spongy moth (lymantria dispar dispar,) an invasive species formerly known as gypsy moth. There are steps you can take to protect trees and minimize the damage done by these hungry pests.
Species of concern
Asian longhorned beetle
Watch list - not detected in Michigan.
The Asian longhorned beetle can attack and kill many tree species. Its favorite host is maple trees, and it also poses a threat to hops and grapes. Beetle larvae feed in tunnels in trees, eventually killing the tree.
Beech bark disease
Present in Michigan.
Beech bark disease is caused by a sap-feeding scale insect and a fungus. Trees are first infested with whitish beech scale, allowing infection by the Neonectria fungus. The fungus kills trees by blocking sap flow. Infected tree limbs can break in heavy winds.
Beech leaf disease
Present in Michigan
Beech leaf disease is associated with a microscopic worm, or nematode. It is identified by symptoms including leaf curling and puckering, thickened leaf stripes, interveinal banding and leaf loss. Repeated years of leaf damage and loss can weaken beech trees, leading to tree death.
Emerald ash borer
Present in Michigan.
The emerald ash borer is a metallic green insect with purple abdominal segments under its wing covers. The larva are worm-like. Adults feed on the foliage of ash tress and the larvae tunnel and feed on the underside of the bark.
Hemlock woolly adelgid
Present in Michigan.
Adelgids are tiny insects that secrete white wax as they feed on sap from hemlock shoots and branches. Hemlock woolly adelgid feeding can kill needles, shoots and branches, resulting in tree death.
Oak wilt disease
Present in Michigan.
Oak wilt disease can quickly kill healthy red oaks and can damage white oaks. Avoid pruning oaks April 15-July 15 when the infection can be spread by beetles in tree wounds.
Spotted lanternfly
Present in Michigan.
The spotted lanternfly sucks sap from the stems and leaves of orchard trees, grape vines, oaks, pines and other plants. Feeding can weaken the plant and eventually contribute to its death. Trees will develop weeping wounds that attract insects and cause mold growth.