Most of the leaf spots and blotches you see on Virginia trees after a wet spring are cosmetic, but a few diseases can kill a tree and are worth catching early.
Bacterial Leaf Scorch
This is one of the most common problems on oaks in the red oak group in Virginia, including willow oak, pin oak and red oak. It also affects elm, sycamore and some maples. The bacteria live in the tree's water-conducting tissue and are spread by leafhoppers and spittlebugs.
Signs
- Leaves turn brown from the edges inward in mid to late summer
- A yellow or reddish band often separates the brown edge from the green center
- It starts on one branch or one side and spreads through the canopy over several years
- It returns every year, a little worse each time
What to Do
There is no cure. Deep watering in dry spells, a wide mulch ring and avoiding root damage help an infected tree hold on longer. Some arborists use antibiotic injections to slow symptoms, but it doesn't eliminate the infection. Over many years, affected trees lose branches and eventually need to come down. Prune dead limbs as they appear.
Dogwood Anthracnose
This fungal disease hits flowering dogwoods hardest in cool, wet springs and in shady, damp spots with poor air flow. It is most severe at higher elevations but shows up across Virginia.
Signs
- Tan leaf spots with purple borders in spring
- Blighted leaves that cling to twigs into winter
- Dieback of twigs and lower branches, working upward
- Clusters of sprouts along the trunk and main limbs
What to Do
- Rake up and remove fallen leaves.
- Prune out dead twigs and trunk sprouts in dry weather.
- Water in drought and keep mulch around the tree.
- Improve air flow by thinning surrounding plants.
- For valuable trees, fungicide sprays starting at bud break can help.
- When replanting, choose disease-resistant flowering dogwood varieties such as 'Appalachian Spring'.
Dogwoods also get powdery mildew, a white dusty coating on leaves in late summer. It's usually cosmetic.
Beech Leaf Disease
This disease, caused by a microscopic worm-like nematode, was first confirmed in Virginia in Prince William County in 2021 and has since been found in Fairfax and Stafford counties. It attacks American beech and can kill trees within several years of infection.
Signs
- Dark stripes between the leaf veins, easiest to see when looking up at leaves from below
- Thick, leathery, curled leaves
- Thinning canopy, usually showing first on lower branches and young trees
What to Do
If you suspect it, photograph the leaves and report the location to the Virginia Department of Forestry's forest health team. Treatments applied by licensed professionals are available for high-value trees and are still being studied.
Laurel Wilt
Spread by an invasive ambrosia beetle, laurel wilt kills sassafras, spicebush and redbay. It was first confirmed in Virginia in Scott County in 2021. Infected trees wilt quickly, often in one season, and there's no cure. The biggest thing homeowners can do is avoid moving firewood.
Oak Decline and Hypoxylon Canker
Oak decline isn't one disease. It's a slow spiral where drought, age, compacted soil or root damage weaken an oak, and then secondary pests like two-lined chestnut borer, root rot and hypoxylon canker move in.
- Early signs are a thinning crown, dead branch tips and smaller leaves.
- Hypoxylon canker shows up as patches of bark falling away to reveal a gray, tan or black crusty fungal layer on the trunk or limbs.
- Once hypoxylon covers large areas of the trunk, the wood underneath is usually decaying and the tree can become dangerous.
Prevention is the only real treatment. Protect oak roots, water mature oaks in long droughts and don't pile soil or mulch against their trunks.
Root Rot
Root rot fungi like Armillaria and water molds like Phytophthora attack roots in poorly drained, overwatered or damaged soil. Because the damage is underground, a tree can look fairly normal until it falls over.
Signs
- Clusters of honey-colored mushrooms at the base of the tree in fall
- White fungal sheets under loose bark at the root flare
- Soft, dark or oozing bark near the ground
- A thinning canopy and dieback with no obvious cause
- A tree that starts to lean, with the soil lifting on one side
A tree showing signs of root rot near a house or driveway should be checked by a professional. It can fail even when the canopy is still green.
Leaf Spots and Anthracnose on Other Trees
Sycamore, oaks and maples often get brown leaf spots or drop leaves after a cool, rainy spring. It looks alarming, but healthy trees put out a new set of leaves and recover. Raking and removing fallen leaves reduces next year's infection.
Cedar-Apple Rust
In spring you may see bright orange, jelly-like horns on round galls in eastern red cedars. They're harmless to the cedar. The disease cycles between cedars and apples or crabapples, and it's the apple side that suffers.
Get a Diagnosis Before You Spray
Many tree problems look alike. Your local Virginia Cooperative Extension office can send samples to the Virginia Tech Plant Disease Clinic for a confirmed diagnosis. That keeps you from spending money on the wrong treatment.