Black Spots on Maple Leaves in Indiana: What to Do This Fall

Raised, black spots on maple leaves in fall may be tar spot—a fungal leaf disease that is usually more of an appearance problem than a threat to an otherwise healthy tree. Confirm the pattern, collect affected fallen leaves and look at the condition of the whole tree before buying a fungicide or considering removal.

For homeowners in Anderson, Pendleton and nearby Central Indiana communities, October leaf cleanup is a useful time to notice these spots. Finding them now does not tell you when infection began, and it does not prove that every other symptom on the tree has the same cause.

What tar spot looks like—and what it does not explain

Tar spot can appear as one raised, black patch or a cluster of smaller black spots, sometimes with a yellow border. The spots begin lighter in color and become distinctly tar-like later in the growing season.

The University of Minnesota Extension maple leaf-spot guide shows several different problems side by side. Irregular dark areas along leaf veins can fit anthracnose, while a soot-like coating associated with sticky leaves suggests a different issue. “Black on a leaf” is not a complete diagnosis.

Look at several leaves, not just the worst one. Photograph both sides and include an image of the entire canopy. A clear close-up helps identify a leaf pattern; the wider photograph helps show whether the concern is isolated or part of broader decline.

Does a maple with tar spot need treatment?

The University of Wisconsin Plant Disease Diagnostics Clinic’s tar spot guidance, revised March 2, 2024, describes the disease as primarily cosmetic and says fungicide treatments are rarely warranted. Tar spot by itself is not a reason to remove an otherwise sound maple.

A fall spray will not make the existing black patches disappear. If there is a reason to consider preventive disease management, the decision belongs with a confirmed diagnosis and the appropriate spring growth stage—not simply with the date you noticed an ugly leaf.

Ask what problem a proposed treatment is intended to address. A leaf-spot concern, a wilted branch and a damaged root system should not automatically receive the same recommendation.

What fall leaf cleanup can accomplish

Tar spot fungi can persist in fallen leaves and produce spores that infect new leaves in spring. Collecting affected leaf litter can reduce that source of infection. It is a practical step, not a guarantee that spots will never return.

• Gather affected fallen leaves as cleanup progresses through the season.
• Use an accepted yard-waste collection or disposal option and follow its material rules.
• If composting, use an actively managed hot pile rather than assuming a cold heap destroys the fungus. Wisconsin recommends about 140°F and regular turning so outer material reaches the hot center.
• Do not simply move intact affected leaves back beneath the same maple as mulch.

Take a few photographs before cleanup. Save the date and note whether the tree shed leaves unusually early. That gives you something concrete to compare with next season.

When the tree needs a closer look

Do not use a likely tar spot diagnosis to dismiss dead branches, a suddenly wilted section, significant canopy thinning or damage around the trunk and roots. Those observations deserve their own assessment.

If one section declined while the rest stayed leafy, our guide to a maple wilting on one side is a more relevant starting point. A tree can have a leaf-spot problem and a separate concern at the same time.

Modern Tree Solutions’ plant health care assessment considers the symptoms, tree condition and growing site before recommending care. Share when the change began, photographs from earlier in the year and any recent digging, watering changes or treatments.

The practical answer: verify the leaf pattern, clean up affected fallen leaves and judge the whole maple. Dramatic-looking spots alone do not establish that a tree is dying or needs a fall spray.