Bacterial Leaf Scorch (BLS)

Signs & symptoms

• Leaf edges browning in mid-to-late summer, often with a yellow band between the brown and green
• The same scorched look returning year after year, a little worse each time
• Symptoms showing up branch by branch, spreading through the canopy over seasons
• Gradual dieback of limbs over several years

Bacterial leaf scorch shows up a lot in the big old oaks around the Philadelphia area. Unlike a dry-weather scorch, it comes back every year and slowly works through the tree, because the bacteria clog the vessels that carry water. There's no cure — it's a long, slow decline measured in years, not weeks.

What we focus on is managing it: keeping the tree as healthy as possible for as long as it's safe, removing deadwood as limbs die back, and keeping an honest eye on when a declining tree over your house has become more risk than it's worth.

What to do

• Keep the tree healthy and watered in droughts to slow the decline
• Have deadwood removed as branches die back, so falling limbs don't become a hazard
• When a scorch-declined tree starts dropping real limbs near the house, it's time for an honest assessment

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