Tree problems · Disease
Leaf spot diseases (anthracnose and tar spot): signs and what to do
Leaf spot diseases (anthracnose and tar spot) is a tree disease, often seen on sycamore and london planetree, maples, ash. Look for: irregular brown or reddish-brown dead patches along leaf edges and veins, a sign of anthracnose.
General information, not a diagnosis. A certified arborist or your county extension office can confirm.
- Disease
- Sycamore and London planetree (anthracnose)
- Maples (tar spot and other leaf spots)
- Ash
- Oaks
- Dogwood
- Walnut
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
Anthracnose is most active in cool, wet spring weather as leaves open. Tar spot on maple usually becomes clear in mid to late summer. Many leaf spots show up in summer and cause early leaf drop in fall.
How it spreads
These fungi overwinter in fallen leaves and twigs. Rain and wind spread the spores to new leaves the next spring.
Where it is found
Leaf spot diseases occur in every state where shade trees grow. They are common landscape problems and not regulated pests.
Official sources
What to do
- 1
Take photos of the leaves and note when the spots appeared and how many leaves are affected.
- 2
Rake up and dispose of fallen leaves in fall to reduce infection the next year.
- 3
Water the tree during dry spells and feed it in spring if a soil test or an arborist suggests it.
- 4
Do not rush to spray. Extension sources say chemical control is usually not needed because these diseases rarely threaten tree health.
- 5
If the same tree drops many leaves several years in a row, ask your extension office or a certified arborist to look at it.
- 6
Rule out sunburn, drought, frost and root damage, since they can look alike.
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
Clean up fallen leaves, keep the tree well watered in dry weather, and avoid wounding the trunk and roots. Prune lightly to let air move through the crown. When you plant, choose species and selections suited to your site. Ask a certified arborist about fungicide only for a high-value tree that is hit hard year after year.
When to call a pro
Call a certified arborist if a tree loses most of its leaves early for several years, if twigs and branches are dying, or if you are unsure whether it is a leaf spot or a serious problem. Pruning big trees near buildings and lines needs a trained, 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: Sycamore and London planetree (anthracnose), Maples (tar spot and other leaf spots), Ash, Oaks, Dogwood, Walnut, Horse chestnut.
- American sycamore
- London Planetree
- Red Maple
- Sugar Maple
- Norway Maple
- Silver Maple
- White Oak
- Green Ash
- White Ash
- Flowering Dogwood
- Black walnut
- Horse Chestnut
See all species in our tree library, or pick a tougher tree with the tree picker.
For tree companies
How to explain leaf spot diseases (anthracnose and tar spot) to a customer
Tell homeowners plainly that most leaf spots are more about looks than tree health. Do not sell removal or costly sprays for them. A fall leaf cleanup tip and a watering plan builds trust. Offer a check if the leaf loss repeats every year.
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 a leaf spot disease?
It is a fungal problem that makes dead spots or patches on leaves. Anthracnose and tar spot are two common kinds on shade trees.
Will leaf spots kill my tree?
Usually not. Extension sources describe these diseases as more cosmetic than life-threatening for a healthy tree. Repeated heavy leaf loss can stress a tree, so keep it watered and ask a pro if worried.
What is the black spot on my maple leaves?
It is likely tar spot. It makes raised black spots on leaves in mid to late summer. It looks bad but is mostly cosmetic.
Do I need to spray?
Most of the time, no. Raking leaves in fall and good tree care are the main steps. Ask your extension office before using a fungicide.
Why does my sycamore look burned in spring?
Sycamore anthracnose can kill new leaves and twigs in a cool, wet spring. It can look like frost damage. The tree often grows a new set of leaves.
Should I rake up the leaves?
Yes. The fungus overwinters in fallen leaves, and removing them lowers the chance of infection next spring.
Can Lirevon diagnose leaf spot diseases (anthracnose and tar spot) 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.
Related tree problems
- Frost cracks (Other damage)
- Cankers (Disease)
- Herbicide damage (Other damage)
- Drought Stress (Other damage)
- Construction Damage (Other damage)
- Girdling Roots (Other damage)