Common Tree Diseases and Pests in Wausau, WI

How to Spot Common Tree Health Problems in Central Wisconsin

Trees in the Wausau area can be affected by a range of diseases and pests that weaken growth, damage branches, and shorten tree life. Knowing the warning signs early can help property owners take action before a tree becomes unsafe or too costly to save.


Below are some of the most common tree diseases and pests found in Wisconsin, along with symptoms to watch for and basic management information.

Tree Diseases Common in Wisconsin

Trees in Wisconsin can be affected by several diseases that weaken growth, damage branches, and reduce long-term health. In many cases, early signs are easy to miss until the tree begins showing major decline. Knowing what to watch for can help property owners take action before a tree becomes unsafe or beyond saving.

Oak Wilt

Oak wilt is one of the most serious tree diseases in Wisconsin, especially for red oak species. It can spread quickly and often causes rapid leaf browning, wilting, and early leaf drop. Infected trees may decline fast, and nearby oaks can also be affected. Avoiding pruning during high-risk periods and acting quickly when symptoms appear can help limit spread.

Oak wilt damage on tree leaves in Wisconsin

Dutch Elm Disease

Dutch elm disease affects elm trees and can cause leaves to yellow, curl, wilt, and die back, often starting in one section of the canopy. The disease spreads through bark beetles and root systems, and it can kill mature elm trees if not addressed. Early removal of infected limbs or affected trees may help reduce further problems.

Dutch elm disease symptoms on an elm tree

Apple Scab

Apple scab is a fungal disease that affects crabapple and apple trees. It often shows up as dark, scabby spots on leaves and fruit, followed by premature leaf drop. While it may not always kill the tree, repeated infection can weaken it over time and reduce its appearance and vigor.

Apple scab damage on crabapple leaves and fruit

Anthracnose

Anthracnose can affect a variety of hardwood trees and often causes brown or dead patches on leaves, leaf curling, and early leaf drop. Wet spring conditions can make the problem worse. While some trees recover well, repeated stress can reduce tree health and make them more vulnerable to other issues.

Anthracnose damage on tree leaves in Wisconsin

Common Tree Pests in Wisconsin

Insects can also cause major damage to trees in the Wausau area. Some pests weaken trees slowly over time, while others can create rapid decline or leave trees vulnerable to breakage and disease. Spotting pest activity early can make a big difference in how a tree is managed.

Emerald Ash Borer (EAB)

Emerald ash borer is one of the most destructive tree pests in Wisconsin and targets ash trees. Signs can include thinning leaves, bark splitting, dead upper branches, and increased woodpecker activity. Left untreated, infested ash trees often decline and die.

Emerald ash borer damage on an ash tree

Spongy Moth

Spongy moth caterpillars feed on tree leaves and can defoliate large sections of canopy during active infestations. Repeated defoliation can weaken trees and make them more vulnerable to stress, disease, and secondary damage. Oaks and other hardwoods are especially at risk.

Spongy moth caterpillar damage on tree leaves

Asian Longhorned Beetle

Asian longhorned beetles bore into hardwood trees and can cause serious structural damage over time. Warning signs may include perfectly round exit holes, sawdust-like material at the base of the tree, and dieback in branches. Because this pest can spread and severely damage trees, early identification matters.

Asian longhorned beetle damage on a hardwood tree

Pine Bark Beetles

Pine bark beetles attack weakened or stressed pine trees by boring under the bark. Infested trees may show fading needles, pitch tubes on the bark, and eventual dieback. Drought stress, storm damage, and poor tree health can make pines more vulnerable to infestation.

Pine bark beetle damage on a pine tree

Preventing Tree Diseases and Pest Problems

Healthy trees are better able to resist disease, insect pressure, and environmental stress. Regular trimming, proper pruning, and early attention to dead or damaged limbs can help reduce risk and improve long-term tree health.


Property owners should also watch for sudden leaf drop, canopy thinning, bark damage, insect activity, or signs of decline. When problems are caught early, trimming may help. In more serious cases, removal may be the safest option to protect nearby trees and property.

Help for Diseased or Damaged Trees in Wausau

If you have concerns about tree decline, pest damage, or unsafe limbs, Albright Enterprises can help you determine the next step. We provide trimming, removal, and related tree services for property owners in Wausau and surrounding areas.