Tree problems · Disease

Tar spot of maple: signs and what to do

Tar spot of maple is a tree disease, often seen on Norway maple, sugar maple, red maple. Look for: pale yellow-green spots on leaves in early summer.

General information, not a diagnosis. A certified arborist or your county extension office can confirm.

Disease
Norway maple
Sugar maple
Red maple
Silver maple
Bigleaf maple

Signs to look for

Tick what you see. More ticks make it more likely, but only an on-site look can confirm.

Pale yellow-green spots on leaves in early summer
Spots slowly turn into raised, shiny black patches that look like drops of tar
Patches are usually about the size of a coin and can join together
Leaves may yellow around the black spots and sometimes drop early in fall
The black patches sit on the leaf surface and the trunk and branches are not marked by them
Heavy infection is more common in wet springs

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Season

Infection happens in spring as leaves open. Yellow spots appear in early summer, and the black tar-like patches show in mid to late summer and fall.

How it spreads

The fungus passes the winter on fallen infected leaves. In spring, spores are released and carried by wind and rain to new leaves. Wet spring weather helps infection.

Where it is found

Tar spot of maple is a common leaf disease on maples in many parts of the United States, with different fungus species on different maples. Check your state official map; ranges change.

Official sources

What to do

1
Confirm the black patches are raised and on the leaf surface. This helps separate tar spot from other leaf spots.
2
Rake up and remove fallen maple leaves in fall. This lowers the fungus that overwinters.
3
Do not compost infected leaves in a pile that stays cool and damp, unless it is a hot, well-managed pile.
4
Water the tree in dry spells and avoid wounding the trunk, so it stays strong.
5
Do not spray a large tree for tar spot. It does not usually threaten the life of the tree.

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

Keep up good yearly care: deep watering in dry weather, mulch kept off the trunk, and no root damage. Where it is a yearly problem, consider a different species or a more tolerant variety when you replant.

When to call a pro

Call a pro if the leaf spots come with early leaf loss for several years, thin crown, dieback, or signs of trunk or root problems. Those point to something more than tar spot.

Not sure who to call? Read how to hire a tree service or check is my tree dangerous?

Trees it affects

Usually seen on: Norway maple, Sugar maple, Red maple, Silver maple, Bigleaf maple.

See all species in our tree library, or pick a tougher tree with the tree picker.

For tree companies

How to explain tar spot of maple to a customer

Explain that tar spot looks bad but seldom harms a healthy maple. Offer leaf cleanup and a general health check instead of a spray program. Honest advice builds trust and repeat calls.

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

Will tar spot kill my maple?

Not usually. It makes leaves ugly and can cause some early leaf drop, but healthy maples generally live with it. Repeated stress from other causes is what usually causes bigger trouble.

Why do the spots look like tar?

The fungus forms a hard, shiny, black structure on the leaf. It is raised and can look like a drop of tar on the leaf surface.

Is it the same as maple leaf scorch?

No. Leaf scorch dries the edges and tips of leaves, often from heat or drought. Tar spot makes defined black patches in the middle of the leaf.

Do I need to remove the leaves?

Raking and removing fallen leaves helps lower next year's spores. It is a simple, low-cost step and does not need chemicals.

Will it come back every year?

It can, especially after wet springs. Severity changes with the weather, so some years are much lighter than others.

Is a fungicide worth it?

For big trees, usually not. Sprays must be timed as the leaves open and are hard to apply to tall canopies. Ask your local extension office before you pay for one.

Can Lirevon diagnose tar spot of maple 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.

When customers spot tar spot of maple, they call

Make sure someone answers. Missed-call text-back, lead follow-up, booking and review requests, set up for you. See our services and pricing.

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