Your trees might look fine from a distance—but up close, something could be wrong. Tree diseases are easy to miss until they've already done serious damage. The good news is that most common tree diseases are treatable when caught early. Here's what to watch for and what to do about it.

Why Tree Health Matters

A diseased tree doesn't just look bad—it can become a genuine safety hazard. Weakened branches break in storms. Root rot destabilizes the whole tree. Fungal infections spread to neighboring trees and shrubs. Catching a problem early protects your property, your yard, and your investment.

Signs Your Tree May Be Diseased

Before diving into specific diseases, here are general warning signs that something is off:

• Discolored, spotted, or prematurely falling leaves
• Unusual growths, cankers, or lesions on the bark
• Dead or dying branches that don't bounce back in spring
• Soft, spongy wood at the base of the trunk
• Fungal growth (mushrooms or shelf fungi) around the roots or trunk
• Excessive sap bleeding or oozing from the bark

If you're seeing any of these, it's worth having a professional take a look.

Common Tree Diseases in Southeast Nebraska

Anthracnose

Anthracnose is a fungal disease that affects ash, oak, sycamore, and maple trees. It typically appears in cool, wet springs and shows up as brown or tan spots on leaves, often following the leaf veins. Severely infected leaves may drop early. While anthracnose rarely kills a healthy tree outright, repeated infections weaken it over time and make it more vulnerable to other stressors.

What to do: Rake and dispose of fallen leaves in the fall to reduce fungal spores. For persistent or severe cases, a fungicide treatment in early spring—before leaves fully emerge—can help. Our team can evaluate the extent of the infection and recommend the right treatment plan.

Oak Wilt

Oak wilt is one of the most serious tree diseases in the Midwest, and it's spreading across Nebraska. It's caused by a fungus that disrupts the tree's water-conducting system, causing leaves to wilt and brown rapidly—often starting at the crown and working downward. Red oaks are especially vulnerable and can die within weeks of infection.

What to do: There's no cure once oak wilt is advanced, but early-stage infections can sometimes be slowed with fungicide injections. The most important step is prevention: avoid pruning oaks between April and July when the fungus spreads most aggressively. If a nearby tree has already died from oak wilt, root-to-root transmission is a real risk—call us for an assessment.

Fire Blight

Fire blight is a bacterial disease that primarily affects trees in the rose family, including crabapples and ornamental pears—both popular in Nebraska landscapes. Infected branches look scorched, with leaves and stems that wilt, turn brown or black, and curl downward without dropping.

What to do: Prune out infected branches at least 8–12 inches below the visible damage, sterilizing your tools between cuts. Copper-based bactericides can help prevent spread during bloom. If the infection has reached the main trunk, the tree may need to be removed.

Emerald Ash Borer (EAB)

Technically an insect rather than a disease, emerald ash borer has devastated ash tree populations across the country and has been confirmed throughout Nebraska. The larvae tunnel under the bark and disrupt nutrient flow, causing the canopy to thin, branches to die back, and eventually the whole tree to fail.

What to do: If you have ash trees, don't wait for symptoms to appear. Preventative insecticide treatments are available and effective—but they need to be applied before the infestation becomes severe. Once a tree is heavily infested, removal is usually the only option. Ask us about EAB treatment options for your ash trees.

When to Call a Professional

Some tree problems are manageable with good maintenance—regular pruning, proper watering, and keeping the area around your trees clean. But when a disease has progressed, or when you're not sure what you're looking at, it's worth getting a professional opinion.

At Aim High Tree Service, we offer insect and disease treatment as part of our full range of services. Our owner is on-site for every job, so you're getting an experienced eye—not a subcontractor.

Practical Tips to Keep Your Trees Healthy

• Prune at the right time of year—late fall and winter are generally safest for most species
• Avoid wounding the bark with mowers or string trimmers, which create entry points for fungal infections
• Water deeply but infrequently to encourage strong root systems
• Mulch around the base of trees (keeping it away from the trunk) to retain moisture and regulate soil temperature
• Remove dead or dying branches promptly—they're a highway for disease and pests

Get a Free Tree Health Assessment

Think one of your trees might be struggling? Don't wait until it becomes a bigger problem. Contact Aim High Tree Service for a free estimate or give us a call at (402) 326-4004. We serve Lincoln and communities throughout Southeast Nebraska, and we're happy to take a look.