Tree problems · Disease
Anthracnose: signs and what to do
Anthracnose is a tree disease, often seen on American sycamore, white oak, bur oak. Look for: irregular tan, brown or black blotches on leaves, often along the veins.
General information, not a diagnosis. A certified arborist or your county extension office can confirm.
- Disease
- American sycamore
- White oak
- Bur oak
- Flowering dogwood
- Black walnut
Signs to look for
Tick what you see. More ticks make it more likely, but only an on-site look can confirm.
0 of 6 signs ticked. Ticks stay in this browser only.
Season
It is most common in cool, wet spring weather as leaves open. Many trees recover when the weather warms and dries.
How it spreads
Fungi live on fallen leaves and twigs and spread in rain splash and wind. Wet weather helps the spores infect new leaves and shoots.
Where it is found
Anthracnose fungi occur across the United States wherever susceptible trees grow, and the main trouble is in wet springs. Check your state official map; ranges change.
Official sources
What to do
- 1
Rake and remove fallen leaves and small twigs in fall and spring.
- 2
Prune dead and diseased twigs during dry weather, and thin the crown for more airflow.
- 3
Water in dry spells, and feed only if a soil test shows a need.
- 4
Do not water overhead on foliage in the evening.
- 5
For a high-value tree with repeated heavy attacks, ask a certified arborist about fungicide timing, since it must go on before infection.
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
Plant resistant kinds where you can, give trees full sun and airflow, and keep them healthy. Clean up leaf litter each year to cut the source of spores.
When to call a pro
Call a pro if a tree loses most of its leaves in many years in a row, has dieback on large branches, or if you are unsure it is anthracnose and not a deadlier problem such as dogwood canker or root rot.
Not sure who to call? Read how to hire a tree service or check is my tree dangerous?
Trees it affects
Usually seen on: American sycamore, White oak, Bur oak, Flowering dogwood, Black walnut.
See all species in our tree library, or pick a tougher tree with the tree picker.
For tree companies
How to explain anthracnose to a customer
Be honest that most cases look worse than they are and trees often grow new leaves. Offer cleanup, pruning and a spring-timed treatment only where repeat damage justifies it. Do not sell fungicide for a one-off wet spring.
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 anthracnose?
It is a group of leaf and twig diseases caused by fungi. They are common on shade trees such as sycamore, oak and walnut, and on dogwood.
Will anthracnose kill my tree?
On most shade trees it rarely kills the tree. Repeated attacks, especially on stressed trees, can weaken it. Dogwood anthracnose is more serious.
Why did my sycamore drop its leaves in spring?
Wet spring weather often causes sycamore anthracnose. The tree usually leafs out again.
Should I spray my tree?
Usually no. Fungicides must be applied before infection and are for repeat problems on valuable trees. Ask a certified arborist first.
Is cleanup really helpful?
Yes. Removing fallen leaves and dead twigs cuts the amount of fungus that can reinfect the tree next spring.
How is it different from other leaf spots?
Anthracnose often follows leaf veins and shoots, and appears in cool wet weather. A local extension office can confirm.
Can Lirevon diagnose anthracnose 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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