Central Pennsylvania has the kind of mixed hardwood forest that disease loves. Plenty of oaks, plenty of maples and sycamores, a humid growing season, and weather that swings hard between wet springs and dry summers. Two of the diseases we get called out for most often in Altoona and Blair County are oak wilt and anthracnose. Both can disfigure a tree fast. One of them can kill it in a single season.
Here is how to tell them apart, what to do if you spot them, and when it’s worth bringing in an arborist.
Key Takeaways
- Oak wilt is a fatal fungal disease that can kill a red oak in weeks. Don’t prune oaks between April and July in Pennsylvania.
- Anthracnose looks alarming but is rarely fatal. Most mature trees recover on their own with good care.
- Leaf symptoms alone are not enough to diagnose either disease. Pattern, timing, and species matter.
- If you suspect oak wilt, stop pruning immediately and call a certified arborist. Fast action matters.
- Both diseases are easier to manage when caught early. Annual tree health checks help a lot.
Oak Wilt: What It Is and Why It Matters
Oak wilt is caused by a fungus called Bretziella fagacearum. It spreads two ways: through the root systems of nearby oaks that have grafted together underground, and through sap-feeding beetles that carry fungal spores from infected trees to fresh pruning cuts or wounds on healthy ones.
Red oaks (red oak, black oak, pin oak, scarlet oak) are the most vulnerable. Once a red oak is infected, it usually dies within a few weeks to a few months. White oaks (white oak, bur oak, swamp white oak) are more resistant and can sometimes survive infection for years, but they can still pass the fungus underground to red oaks nearby.
How to Identify Oak Wilt
- Leaves wilt from the top of the tree down and from the outside of the canopy inward
- Leaves turn bronze, brown, or copper from the tip and edges toward the central vein
- Affected leaves drop quickly, often while still partly green
- Symptoms usually appear in mid to late summer
- In red oaks, the entire canopy can brown out in two to six weeks
- Fungal mats may form under the bark in late winter or spring, sometimes cracking the bark
What to Do If You Suspect Oak Wilt
Stop pruning. Right now. Any fresh wound on a healthy oak during the active season is an invitation for beetles to bring spores in. The Pennsylvania DCNR recommends avoiding oak pruning from April through July. If a storm breaks a limb during that window, paint the wound immediately with tree paint or shellac. It’s the one situation where wound dressing is actually the right call.
Then call an arborist. A confirmed diagnosis usually requires a lab sample. Once it’s confirmed, the standard treatment options are:
- Trenching or root-graft disruption to stop underground spread to neighboring oaks
- Fungicide injections (propiconazole) for high-value white oaks not yet infected
- Removal and proper disposal of infected red oaks before the fungus can mat and spread
- Avoiding firewood transport from infected trees, which moves the disease to new areas
Anthracnose: What It Is and Why It Looks Worse Than It Is
Anthracnose is a group of fungal diseases caused by several related species (Apiognomonia, Discula, Colletotrichum, and others). Each one tends to target specific trees. In Blair County, we see it most often on sycamore, white oak, maple, ash, and dogwood. Cool, wet spring weather is what wakes it up, which is why some years are bad and others are not.
Unlike oak wilt, anthracnose rarely kills a healthy mature tree. It’s mostly a cosmetic problem and a stress factor. Repeated heavy infections year after year can weaken a tree and make it vulnerable to other issues, but a single bad anthracnose year is usually nothing to panic about.
How to Identify Anthracnose
- Irregular brown or tan blotches on leaves, often along the veins
- Leaves curled, cupped, or distorted, especially new spring growth
- Early leaf drop in spring or early summer
- Dieback at the tips of small twigs and branches
- On sycamores: bare patches in the canopy in early summer that often refoliate later
- Sunken cankers on twigs in severe cases
Treating and Managing Anthracnose
Most of the time, the right treatment is patience plus good cultural care:
- Rake up and dispose of fallen leaves in autumn to reduce spores overwintering on site
- Prune out dead or cankered twigs in dry weather and disinfect tools between cuts
- Improve airflow through the canopy with proper structural pruning
- Water deeply during dry stretches to reduce stress on the tree
- Mulch the root zone (but not against the trunk) to keep soil moisture steady
- Fungicide treatments are usually only worthwhile on high-value ornamentals or repeatedly hard-hit specimens
Other Tree Diseases We See in Blair County
Oak wilt and anthracnose get most of the attention, but they aren’t the only diseases worth knowing about in Central PA:
- Dutch elm disease: still active in remaining American elms
- Apple scab and fire blight: common on crabapples, pears, and apples
- Verticillium wilt: affects maples, ashes, and many other species
- Cytospora canker: shows up on spruces, especially older Colorado blue spruce
- Needlecast diseases: affect spruces and pines, causing inside-out needle drop
- Beech leaf disease: a newer arrival spreading across Pennsylvania
When to Call an Arborist
If you’re seeing browning leaves, dieback, or anything that just looks off, a quick arborist consultation is worth the time. A proper diagnosis matters because the right treatment for one disease is the wrong treatment for another. Pruning an oak in June because the leaves look bad can turn a minor problem into a fatal one.
Our team at Lofty Heights includes ISA Certified Arborists who diagnose tree diseases across Altoona, Hollidaysburg, Tyrone, Duncansville and the rest of Blair County. We’ll tell you what’s going on, what’s treatable, and what isn’t, in plain language.
