Like all trees, maples can suffer from a variety of diseases that affect their health, appearance, and longevity.
From fungal infections to environmental stress, knowing what to look out for—and how to respond—can make a big difference in saving your tree.
This guide outlines five of the most common maple tree diseases, how to identify them, and what you can do if your tree is affected.
Maple tree sickness
Most maple tree diseases and sicknesses can be easily observed, but some require specialist detection. Contact a local tree expert if you’re unable to ascertain what’s wrong with your tree after checking this guide.
Amazon has a range of products for preventing and treating maple tree diseases, which you can view here. However, some problems cannot be treated, so prevention is key.
These are the primary reasons a maple tree may appear poorly.
1. Verticillium Wilt
Symptoms: Wilting leaves, dieback of branches, discolored or streaked wood beneath the bark, and overall poor vigor.
Verticillium Wilt is one of the most serious diseases a maple tree can get. It’s caused by soil-borne fungi—Verticillium albo-atrum or Verticillium dahliae—that invade the tree through its roots and interfere with water movement.
Symptoms often start on one side of the tree and can include yellowing or browning leaves, premature leaf drop, and branch dieback. When you cut into an affected branch, you might see dark streaks in the sapwood.
Unfortunately, there’s no cure for Verticillium Wilt once a tree is heavily infected. You can prolong a mildly affected tree’s life by removing diseased limbs, improving soil health, and ensuring the tree is well watered and mulched.
Avoid planting new maple trees in soil where this disease has been present, as the pathogen can survive for years in the ground.
@pegasus_hort shared:
Verticillium on Acer rubrum – Red Maple.
Very common on Japanese maples, and less so on Red Maple, it is a soil borne disease that causes a vascular wilt that is usually fatal.
It is caused by the organisms Verticillium dahliae and Verticillium albo-atrum, which usually enter the roots via nematodes, or damaged roots as in the case of the early freeze where carbohydrate production abruptly ceased leaving small immature roots to rot.
Notice the characteristic V-shaped lesion on the leaf, and the staining of the wood. Verticillium persists in the soil, and do not replant susceptible plants such as susceptible maples, Redbud, Ash, Catalpa, Golden Raintree, Dogwood, or Smoke Tree.
2. Anthracnose
Symptoms: Irregular brown blotches along leaf veins, leaf curling, premature leaf drop, and occasional twig dieback.
Anthracnose is a fungal disease that thrives in cool, wet spring weather. It’s caused by a group of fungi (often Discula or Colletotrichum species) that infect leaves and sometimes twigs.
The first signs are usually dark brown or blackened areas along the veins of young leaves. As the infection spreads, it can cause leaves to curl, wither, and fall prematurely. In severe cases, twigs may also become infected and die back.
While anthracnose can look alarming, it’s usually not fatal for mature trees. Most maples will grow a second flush of leaves in summer.
To manage anthracnose, rake and destroy fallen leaves in autumn to prevent overwintering spores. You can also prune out infected twigs during dormancy. For trees with a history of severe anthracnose, a fungicide treatment applied early in the season may help reduce future infections.
3. Tar Spot
Symptoms: Round, raised black spots on upper leaf surfaces, usually appearing in late summer or early fall.
Tar spot is a distinctive and easily recognizable maple leaf disease caused by fungi in the Rhytisma genus, particularly Rhytisma acerinum.
The fungus creates glossy, tar-like spots that can be up to half an inch across. These spots don’t usually show up until mid to late summer, and while unsightly, they rarely cause serious harm to the tree.
Since tar spot is primarily a cosmetic issue, treatment usually isn’t necessary. However, the best way to manage it is through good sanitation. Infected leaves should be raked and removed from the ground in the fall to reduce the spread of fungal spores the following spring.
Fungicides are generally not recommended unless the tree is small and the disease has been especially persistent year after year.
@hi_im_a_fungi shared the following description with their image:
Silver maple leaf infected with a fungal disease known as tar spot. This disease can be caused by several different ascomycete species in the genus Rhytisma.
The fungus overwinters on the fallen leaves and can then infect new leaves the following spring. This disease does not usually affect the health of the tree and is mostly cosmetic.
I really like how they look like little black brains.
4. Leaf Scorch
Symptoms: Brown, dry edges on leaves, especially during hot, dry weather. Leaves may curl or fall prematurely.
Leaf scorch is not caused by a pathogen but by environmental stress, such as drought, excessive heat, wind, or root damage.
It often occurs during the summer when water demand exceeds supply. Affected leaves develop brown, crispy edges while the veins remain green. In more severe cases, entire leaves may curl and fall from the tree.
Preventing leaf scorch involves proper watering and care during dry spells. Mulching around the base of the tree helps retain soil moisture and regulate temperature. While leaf scorch isn’t contagious or necessarily fatal, it is a sign the tree is stressed and may become more susceptible to pests or diseases if conditions don’t improve.
Ensuring the tree gets adequate water—especially during dry summers—is key to recovery.
5. Powdery Mildew
Symptoms: White, powdery coating on leaves, especially on the upper surfaces. Infected leaves may curl, discolor, or drop early.
Powdery mildew affects a wide variety of trees and plants, and maples are no exception. The fungus thrives in warm, dry climates with high humidity and poor air circulation.
Early signs include a white or grayish film on the leaves. Over time, the infected leaves may become distorted or stunted, and in severe cases, they might fall off prematurely.
While powdery mildew looks dramatic, it’s rarely fatal to a healthy tree. You can reduce its spread by improving air circulation around the tree—prune dense growth and avoid overcrowding.
Water at the base of the tree rather than overhead to keep foliage dry. Fungicides are available for severe cases, but they’re usually not necessary unless the infection is recurring and impacts tree growth.
@thetreecouncil shared:
Our Director of Trees, Science & Research, Jon found powdery mildew on field maple, which he had never seen before on this particular tree.
Let us know in the comments if you have ever seen powdery mildew on field maple or other species of tree! 🌳
Can you use wood from diseased maple trees?
Yes—often you can. In most cases, wood from a diseased maple tree can still be used for firewood or other non-structural purposes, as long as it’s handled correctly.
Here are a few important considerations:
Allow it to season properly. This helps reduce moisture and kill off any remaining pathogens or pests.
Avoid spreading diseases. If the disease is soil-borne, like Verticillium Wilt, don’t transport firewood across regions or use wood chips as mulch near healthy trees.
Inspect for pests. Some tree diseases attract insects. If the wood is infested, treat or burn it quickly to prevent spread.
Burn safely. Firewood from diseased trees should only be burned in properly maintained fireplaces or wood stoves.
Even if the tree is sick, the wood is still useful—you just need to take a few precautions to avoid spreading anything to healthy trees in the area.
Keep an eye on your maple
Like oak trees, maples are generally hardy and long-lived, but they’re not invincible.
Leaf discoloration, cankers, and dieback can all be signs that something is wrong. Fortunately, many maple tree diseases can be managed—especially when caught early.
Regular pruning, proper watering, and avoiding injury to the trunk and roots go a long way in keeping your tree healthy. If you notice any of the symptoms mentioned above, take action promptly.
In some cases, a bit of cleanup and care is all that’s needed. In others, you may need to consult with an arborist or apply a targeted treatment. With the right approach, you can protect your maple from disease and enjoy its shade and beauty for decades to come.