Tree problems · Disease
Bacterial leaf scorch: signs and what to do
Bacterial leaf scorch is a tree disease, often seen on red oaks and pin oaks, white oak, red maple. Look for: leaf edges that die and turn light brown, often with a dark reddish-brown band and a yellow border next to the green part.
General information, not a diagnosis. A certified arborist or your county extension office can confirm.
- Disease
- Red oaks and pin oaks (most affected)
- White oak
- Red maple
- Elms
- Sycamore and London planetree
- Sweetgum
Signs to look for
Tick what you see. More ticks make it more likely, but only an on-site look can confirm.
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Season
Leaf browning usually shows in mid to late summer and into early fall. On some trees it starts as early as late June or July. The tree can look fine for a year or two after infection and then decline slowly over several years.
How it spreads
The cause is a bacterium that blocks the tree's water-carrying tissue. Sap-feeding insects such as leafhoppers, treehoppers and spittlebugs carry it from tree to tree.
Where it is found
Bacterial leaf scorch has been reported in many parts of the eastern and southern United States. Extension services in several states list it as a common problem on red and pin oaks. Check your state official map; ranges change.
Official sources
What to do
- 1
Take clear photos of the leaves and the whole crown in late summer, and note which trees show the pattern.
- 2
Rule out drought, root damage, soil changes and sun scorch first, since they look alike.
- 3
Ask your county extension office or a plant clinic about lab testing to confirm.
- 4
Water the tree during dry spells and protect its roots from digging and compaction.
- 5
Ask a certified arborist whether the tree is stable enough to keep, and what to expect over the coming years.
- 6
Remove dead limbs over houses, driveways and play areas, and plan removal if the tree becomes a hazard.
Safety first: do not climb, do not cut near power lines and do not use a chainsaw on storm-loaded wood. Call the utility for downed lines and 911 if anyone is in danger.
Prevention
There is no cure. Extension sources say removing a sick tree may not stop the spread, because the bacterium is widespread. Good care helps trees stand up longer: water in dry weather, mulch correctly, avoid root damage. Some arborists offer injections that ease symptoms for a season but do not cure the tree, so ask what results to expect and what it costs each year. When you replant, use a mix of species.
When to call a pro
Call a certified arborist if the crown is thinning year after year, large limbs are dying, or the tree is near a house, road or power line. A slowly declining tree can drop dead wood, so removal or pruning near targets is work for a trained and insured crew.
Not sure who to call? Read how to hire a tree service or check is my tree dangerous?
Trees it affects
Usually seen on: Red oaks and pin oaks (most affected), White oak, Red maple, Elms, Sycamore and London planetree, Sweetgum, Mulberry.
- Northern Red Oak
- Pin Oak
- White Oak
- Red Maple
- American Elm
- American sycamore
- London Planetree
- Sweetgum
- Red Mulberry
See all species in our tree library, or pick a tougher tree with the tree picker.
For tree companies
How to explain bacterial leaf scorch to a customer
Be clear that leaf scorch looks like drought, so a lab test is the honest first step. Do not promise a cure. Explain the options in plain words: monitor, ease symptoms, or remove. Give written quotes and let the owner decide without pressure.
Send this page to the customer after your visit so they can read the signs in plain words. See also selling plant health care and the job photo checklist.
Questions
What is bacterial leaf scorch?
It is a disease caused by a bacterium that blocks the water-carrying tissue in the tree. The leaves brown at the edges in late summer, and the tree declines over several years.
How can I tell it from drought?
They look alike. A clue is a yellow band between the dead brown edge and the green part of the leaf, and symptoms that return every year even when the tree is watered. A lab test gives the answer.
Can a tree with leaf scorch be saved?
There is no cure. Good care can help a tree last longer, and some injections may ease symptoms for one season. Ask a certified arborist to judge your tree.
Which trees get it most?
Red oaks and pin oaks are the most affected in extension reports. Other trees such as elm, sycamore, red maple, mulberry and sweetgum can also get it.
Will it spread to my other trees?
Insects can carry the bacterium to other susceptible trees nearby. Spread is hard to prevent, so keep your other trees healthy and watch them.
Is it dangerous to leave the tree standing?
A tree that is slowly dying can drop dead branches. Have a qualified arborist check it if it stands over a house, driveway or play area.
Can Lirevon diagnose bacterial leaf scorch on my tree?
No. Lirevon is a remote marketing team for tree service companies and does not do tree work. This page is general information, not a diagnosis. A certified arborist or your county extension office can confirm what is wrong with your tree.
How do I find a good local pro for this?
Search Google Maps for certified arborists or tree services near you, read their reviews and ask for proof of insurance. Get two or three written quotes. Our guide on how to hire a tree service lists the questions to ask.
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