Forest Health
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Find Forest Health Help
For sick forest trees, contact a DNR forest health specialist or forester. For sick yard trees, contact a certified arborist or visit the University of Wisconsin-Madison Extension's Ask Your Gardening Question page.
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Spongy Moth
Those currently experiencing a spongy moth infestation are also invited to visit the interagency Wisconsin Spongy Moth Resource Center [exit DNR]. The European spongy moth (Lymantria dispar) was accidentally introduced into Massachusetts in 1869 by…
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Forest Tent Caterpillar
The forest tent caterpillar is an important leaf-eating (defoliating) caterpillar in Wisconsin. Some people call forest tent caterpillars "army worms" because as they travel across the ground they look like marching soldiers. Distribution Forest…
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Emerald Ash Borer
Emerald ash borer (Agrilus planipennis) is an invasive, wood-boring beetle that kills ash trees (Fraxinus spp.) by eating the tissues under the bark. Native to northeastern Asia, emerald ash borer (EAB) was first detected in the United States in…
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Beech Bark Disease
Beech bark disease is a major threat to American beech (Fagus grandifolia) in eastern North America. The disease is the result of an interaction between an insect (a scale) and a fungus (Neonectria) and it only happens when both are present.
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Bark Beetles and Associated Issues
Bark and ambrosia beetles (family Curculionidae, subfamily Scolytinae) are a diverse group of wood-boring beetles found in every forest type across the world. The United States and Canada are home to approximately 600 species of bark and ambrosia…
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Asian Longhorned Beetle
Learn here how to identify Asian longhorned beetle, where it is and how to help keep it from moving to new places. This pest is a serious threat to Wisconsin forests because it can attack many different tree species, even when the trees are…
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Heterobasidion Root Disease (HRD)
The Wisconsin DNR maintains the locations of all stands confirmed with HRD. If you suspect HRD in your stand, please contact forest health staff for confirmation and consultation. Heterobasidion root disease (HRD), formerly known as annosum root…
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Hemlock Woolly Adelgid
Hemlock woolly adelgid (Adelges tsugae) is a tree-killing insect that was accidentally introduced to eastern North America. It can become a threat to Wisconsin’s eastern hemlocks if it arrives here. Learn where this pest is now, what it looks like…