A Growing Threat to Oaks in Our Area

If your oak trees are looking stressed or dropping leaves early, Bacterial Leaf Scorch (BLS) could be the cause. This bacterial disease has become increasingly common across Bucks and Montgomery Counties in Pennsylvania.

BLS is caused by a bacterium that clogs a tree’s internal water system, blocking the flow of moisture and nutrients. Over time, this leads to leaf scorch, thinning canopies, and gradual decline. Oaks—especially pin, red, and scarlet oaks—are the most vulnerable, though other hardwoods can be affected too.

Even if you’re not sure what types of trees you have, our certified arborists can identify oak species during an inspection and check for early warning signs.

How to Recognize the Early Warning Signs

Because the disease works slowly, it can be easy to overlook at first. Watch for these indicators in late summer and early fall:

• Scorched leaf edges — showing brown or reddish margins with green centers—are an early warning sign, typically occurring in an irregular pattern throughout the tree.
• Premature leaf drop in August or September (oaks usually hold leaves later).
• Thinning canopy or dead branch tips.
• Overall decline in color and fullness compared to past years.

Early identification gives your trees the best chance for long-term stability and appearance.

What Happens If It’s Left Untreated

Bacterial Leaf Scorch doesn’t kill a tree overnight—it progresses year by year. As the bacteria spreads through the vascular system, water flow becomes more restricted. The canopy thins, branches die back, the tree gradually weakens, often succumbing within 5–10 years.

Eventually, untreated trees can become hazardous, posing safety risks from falling limbs near homes, driveways, or sidewalks. In many cases, property owners face emergency removals that could have been avoided with early management.

Professional Treatments That Can Help

Our professional treatments can slow BLS progression and prolong a tree’s useful life.

Our arborists typically recommend:

• Annual antibiotic injections in late spring or early summer to help restore internal water movement to the canopy.
• Tree Balance Program every 3 years (can be done now) to:
  • Stimulate fine root growth that absorbs water and nutrients.
  • Reduce canopy size and water demand.
  • Help balance the tree’s internal water supply.
• Supplemental care: because this disease progresses faster under drought stress, it’s important to pair injections with supplemental care such as soil fertilization, deep root bio-hydration treatments, and ongoing soil health management to strengthen the tree’s defense system.

Our goal is simple — to stop decline, improve appearance, and extend your tree’s healthy lifespan.

Why Early Detection Matters

The earlier a tree is diagnosed, the more options you have for effective management. Starting treatment in the early stages of BLS can maintain the tree’s health for many years and reduce the need for heavy pruning or removal.

Annual inspections are especially valuable for mature oaks and other high-value trees near homes and structures.

How Homeowners Can Help Between Treatments

Homeowners play an important role in supporting tree health between professional visits.

• Water during droughts to reduce stress on the root system.
• Maintain a mulch ring around the base to keep roots cool and retain moisture.
• Avoid soil compaction near roots — don’t park, repetitively walk or store materials under trees.
• Schedule annual inspections to track canopy health and catch problems early.

Strong roots and healthy soil are key to keeping Bacterial Leaf Scorch in check.

Frequently Asked Questions About Bacterial Leaf Scorch

Q1: What causes Bacterial Leaf Scorch?

The disease is caused by a bacterium that blocks the tree’s internal water flow. It’s transmitted naturally by leafhoppers and spittlebugs feeding on sap.

Q2: Can it spread to other trees?

Yes, but only to other susceptible species—mainly oaks and sometimes maples. It doesn’t spread through the air, rain, or pruning tools.

Q3: Can my tree recover?

There’s no permanent cure, but professional treatments can slow disease progression and keep your tree healthy and attractive for many years.

Q4: When is the best time to treat?

Antibiotic injections work best in late spring through early summer. Growth regulator treatments can be applied anytime during the growing season.

Q5: How can I tell if my tree is an oak?

Oaks have distinct lobed leaves and acorns, but identification can be tricky—especially between species. Our certified arborists can confirm what’s growing on your property during an inspection.

Q6: Should I remove a tree with Bacterial Leaf Scorch?

Not necessarily. Many infected trees can live for years under a consistent care program. Tree removal is only advised when decline becomes severe or the tree poses a safety hazard.

Schedule a Professional Inspection This Season

If your trees are showing scorched leaves or early leaf drop, now is the time for a professional inspection. Even if you’re not sure whether you have oaks, our team can help identify your trees and detect early signs of disease before decline sets in.

Contact Willow Tree and Landscaping Service today at 267-589-1231 to schedule your inspection.

Since 1983, Willow has provided professional, safety-focused tree care throughout Bucks, Montgomery, Mercer, and Hunterdon Counties. Our certified arborists are here to protect your property, preserve your trees, and help them thrive for years to come.