Oak Wilt

Signs & symptoms

• Leaves browning from the edges inward, often starting at the top of the canopy
• Sudden, rapid leaf drop in summer — sometimes the whole tree in weeks
• Browning leaves falling while still partly green
• Red oaks declining much faster than white oaks nearby

Oak wilt is one of the more serious tree diseases we keep an eye on, because it moves fast and spreads — through connected root systems between neighboring oaks, and by beetles drawn to fresh wounds. Red oaks can go from healthy to dead in a single growing season; white oaks tend to hold on longer.

Because it spreads, timing matters. Pruning oaks during the active season can open fresh wounds that invite it in, which is why we avoid pruning oaks in the high-risk warmer months unless there's a safety reason.

What to do

• Avoid pruning oaks in spring and summer — save non-emergency oak work for the dormant season
• If an oak is browning and dropping leaves fast in summer, don't wait — get it looked at
• A confirmed-dead oak should be removed properly to reduce the spread to nearby oaks

This is general guidance from three decades of tree work across the Philadelphia area — not a formal diagnosis. When it matters, we'll come look at the actual tree and give you a straight answer, free.

Trees we see this on

Frequently asked questions

Other tree problems