Tar Spot on Maple Trees: Symptoms, Treatment & When to Worry

You step outside on a late summer morning and notice your maple tree is covered in leaves splattered with bold, raised black spots. It looks like something serious — maybe even fatal. Before you panic, take a breath. What you're most likely looking at is Tar Spot, one of the most visually dramatic yet least harmful fungal diseases affecting maple trees across the eastern and midwestern United States.

Here's everything homeowners and land managers need to know about Tar Spot identification, treatment, and management.

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What Is Tar Spot?

Tar Spot is a fungal disease that affects maple trees, producing the distinctive raised black markings that give it its name. Despite how alarming the spots look, this disease carries a low severity rating — meaning it poses virtually no meaningful threat to the long-term health or survival of your tree.

The fungus responsible for Tar Spot overwinters in fallen leaves on the ground. When spring arrives, it releases spores that infect newly emerging foliage, beginning the cycle again. Cool, wet years tend to produce the most severe outbreaks, which is why you may notice it more in some seasons than others. For the full scientific profile of this disease, see our full ailment details.

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How to Identify Tar Spot

Tar Spot identification is straightforward once you know what to look for. This disease has a very recognizable progression throughout the growing season:

• Early summer: Look for small, light green or yellowish areas beginning to appear on the upper surface of maple leaves.
• Late summer: Those light patches darken dramatically, transforming into raised, black, tar-like spots that are roughly circular and can measure up to half an inch in diameter.
• The spots appear almost exclusively on the upper leaf surface and have a distinctly raised, glossy texture that mimics a drop of tar — hence the name.
• In heavy infection years, you may notice some minor early leaf drop, but this is not a sign of serious decline.

The good news: if your maple looks like it's been splattered with roofing tar in August, you almost certainly have a cosmetic issue and nothing more. Not sure what you're seeing? Try our diagnosis tool to confirm your identification.

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Where Is Tar Spot Spreading?

Tar Spot is well-established and very common across a broad swath of the northeastern, midwestern, and mid-Atlantic United States. Affected states currently include:

Connecticut, Iowa, Illinois, Indiana, Massachusetts, Maryland, Maine, Michigan, Minnesota, Missouri, Nebraska, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, South Dakota, Virginia, Vermont, Wisconsin, and West Virginia.

If you live in any of these states and have maple trees on your property, Tar Spot symptoms are something you're likely to encounter at some point — particularly during cool, wet growing seasons.

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Tar Spot Treatment Options

Here's the most important thing to understand about Tar Spot treatment: in most cases, no treatment is necessary at all.

Because Tar Spot is almost entirely cosmetic and does not harm tree health, fungicide applications are not recommended for landscape trees. Spraying your tree with fungicide carries cost, environmental impact, and logistical challenges — and it simply isn't warranted for a disease that won't hurt your maple.

The one management strategy that genuinely makes a difference is also the simplest:

✅ Fall Leaf Cleanup Because the Tar Spot fungus overwinters in fallen leaves, raking and removing maple leaves in autumn is your most effective tool for reducing next year's infection pressure. You don't need to burn the leaves — both composting and municipal leaf collection work well, since the fungus does not survive the composting process. A thorough fall cleanup won't eliminate Tar Spot entirely, but it can meaningfully reduce how severe the following season's outbreak will be.

✅ Do Nothing (Seriously) If leaf cleanup isn't practical for your property — say, you have a large wooded lot — rest assured that leaving the leaves will not harm your tree. The disease will return next year with more vigor, but your maple will continue to thrive regardless.

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When to Call an Arborist

Given Tar Spot's low severity, most homeowners will never need professional help managing it. However, there are situations where reaching out to a certified arborist makes sense:

• You're not certain of your diagnosis. Other maple diseases and conditions can have more serious consequences. If you're unsure what you're seeing, a professional evaluation provides peace of mind.
• Your tree is showing other signs of stress — such as dieback, unusual bark discoloration, wilting, or structural concerns — that go beyond spotted leaves.
• Significant early leaf drop is occurring year after year and you want a comprehensive assessment of your tree's overall health.

A certified arborist can confirm your diagnosis, rule out more serious conditions, and give you a full picture of your tree's health. Use our find an arborist tool to locate an ISA Certified Arborist in your area.

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Tar Spot is a perfect reminder that not everything that looks frightening in the garden is actually dangerous. Your maple's dramatic black spots are far more startling to you than they are harmful to the tree. A good fall cleanup and a little patience are all you need.