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5 Maple Tree Problems to Watch Out For

closeup of the tar spots on the leaves of a maple tree

Maple trees are some of the most prevalent trees in gardens and yards. Larger varieties, such as the sugar maple, are perfect for providing beautiful shade on hot summer days. They also can be decorative, smaller trees, such as the Japanese maple. Maples come in various shapes and can be found in many varying climates across the world. Maples will thrive in many different growing conditions and can make the average garden into a spectacular garden with its many varieties.

Though most maple trees live long and healthy lives, it’s important to recognize maple tree problems if and when they do arise so you can treat them properly and keep your maple trees happy and healthy for years to come. Below are some common maple tree problems you may run into from time to time in your garden while caring for your maple trees.

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  1. Powdery Mildew

Many maple leaf problems can be diagnosed by looking at their leaves. One of the many diseases that you will find in a hot and humid climate is powdery mildew, which builds up on the maple leaves. This will often show up in mid- to late summer and isn’t considered a threat to the life of the maple tree. You may notice your maple leaves are covered in what looks like a coating of dust or white powder that can be wiped off. This is caused by fungal growth and is purely a cosmetic issue.

You can wipe off the powdery mildew buildup, and to keep it off, you can apply horticultural oil to the leaves. However, this can also burn the maple leaves and can be harmful to pollinating insects such as honeybees, as horticultural oils are also insecticides. Since powdery mildew only causes cosmetic changes in the leaves for the remainder of the season, it’s best to leave the powdery mildew as is.

  1. Anthracnose

Anthracnose is another fungal growth that manifests through changes to the maple tree leaves and branches. Some indicators you may see on your maple tree leaves that indicate there is a fungal growth are browning on the edges or browning along the veins in the leaves. The leaves will eventually shrivel around the brown spots and then drop to the ground.

Anthracnose is caused by several different fungi and typically found in wetter conditions, such as a very wet springtime. If you notice your maple leaves turning brown, then curling and dropping to the ground, it’s best to prune back the branches that have been left bare. Remove any dead fallen leaves from around the tree to prevent further spread of the fungus. No further treatments are required, as it will resolve once the weather dries.

  1. Tar Spot

You may notice your maple leaves have some dark spots in varying sizes. Some may be as small as a tiny dot, while others may be larger, spanning a couple of inches. If the black spots are surrounded by a yellow edge, these spots are known as tar spots. They’re usually found on leaves in the late summer or fall months, and for good reason. The fungi that cause these tar spots to form are found in decomposing leaf piles.

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To prevent tar spots from forming on your maple leaves, it’s always a good idea to clean up fallen leaves before they start breaking down, thus stopping fungi from growing around your maple tree. Once again, these tar spots are purely cosmetic, and no treatment is required for this issue.

  1. Verticillium Wilt

The above three fungal diseases cause leaves to drop and other cosmetic damage that resolves on its own during the next spring bloom. Verticillium wilt, however, is a more serious disease that can kill your maple tree and will require the affected maple trees to be treated and/or removed and replaced with more resistant varieties. If you notice wilting leaves that are often yellowing and confined to a specific area of the maple tree, you may be dealing with verticillium wilt.

This disease often shows up in dry and hot summer months. Verticillium wilt is caused by a fungus that is found in the soil below the tree. The fungus enters the tree through its roots and blocks water and nutrients from entering the tree. Leaves at the top start yellowing first, followed by the leaves below. The fungus will cause smaller tree limbs to die, followed by larger ones. Tree death can happen within a few years, or the tree may survive for a long time with more and more branches falling off through the years.

There is no cure for the disease. If you suspect your tree may have verticillium wilt, contact your arborist experts at Mr. Tree to help. To avoid putting your maple tree at risk of verticillium wilt, protect your tree’s roots by making clean cuts if needing to cut any roots back. Damaged roots with torn edges are more susceptible to Verticillium.

  1. Leaf Scorch

During those hot and dry summertime months, your maple trees will require more water than in the rainy springtime, especially if the summer is unusually hot or dry. If you notice your maple tree leaves browning and becoming dry and brittle, consider watering your maple trees more frequently to keep the moisture levels higher and supplement the lack of rainfall. You can also apply mulch around the tree base to help keep moisture in the ground and around where the tree roots are found. Younger maples are more susceptible to leaf scorch, as they don’t yet have an established root system to rely on for hydration.

To find out more information about your maple tree and possible diseases, check out the Penn State Extension online, which lists these diseases and more. If you need help determining if your maple tree needs further care, contact your tree experts and Mr. Tree.


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