Maple Tree Diseases

Maple Wilt

One of the most common maple tree diseases is known as maple wilt or verticillium wilt. The disease is caused by verticillium, a fungus that is found in the soil. This is a common and serious problem that can kill even established trees.

The disease starts in the root system and spreads up through the sapwood into the upper branches of the tree, causing the big limbs to start dying back.

A tree with maple wilt may have browning or scorched-looking leaves, and diseased branches will have small amounts of sick-looking leaves. Sometimes olive-colored streaks will be found in the sapwood of an affected tree. Cut the bark and look for these streaks, then take the bark to your county extension office for confirmation.

A healthy, vigorous, well-established tree may be able to beat maple wilt, but most trees will die within a season or two of showing symptoms. Unfortunately the best way to control the disease is to destroy infected trees to keep it from spreading.

If that's not an option, or the tree is not seriously infected, pruning out the affected branches may help the tree survive. Keep the tree well-watered during the time it is trying to heal.

Maple wilt seems to be most common in Norway maples, but is also found in silver, sugar, red, sycamore and Japanese maples.

Anthracnose

A group of related fungal diseases that attack maples are called anthracnose. Similar fungi attack other trees such as sycamore, white oak, elm and dogwood trees. They cause a loss of leaves and are usually relatively harmless when the disease only strikes once.

This type of fungus is particularly common after unusually cool, wet winters and can affect bud formation, kill small twigs and leaves or cause premature and repeated early loss of leaves. On maple trees in particular, you may see purplish-brown areas along the veins of the leaves.

If the damage continues year after year, it could predispose the tree to other problems. The best ways to prevent the disease from coming back include removing all affected leaves, twigs and branches and burning them. Fungicide may also be helpful, but seek the advice of a tree doctor before using this method.

Tar Spot

Tar spot is an ugly but mostly harmless disease that strikes several maple species. It causes large, black, tar-like spots on leaves.

The fungus lives through the winter on fallen leaves and then spreads to new leaves in the spring when it is moist. The leaf spots start out yellow and evolve into a dark, tar color.

Treatment is generally not recommended for tar spot because it is usually not a serious problem.

Sapstreak

Sapstreak is a fungal disease that affects sugar maples. It is a fatal disease that discolors the wood, so salvage is not possible.

The disease causes the foliage at the crown of the tree to become smaller, and bald spots often appear. Over time this dwarfing spreads and the tree ultimately dies. When the tree is cut down, a radiating pattern will be seen in the wood of the lower part of the tree.

The only way to get rid of sapstreak is to cut down the tree as soon as possible after noticing the problem. Sapstreak can spread with the help of insects through wounds on the trees, so it's important to keep your trees healthy if you have multiple maples.

This disease is mostly seen in parts of North Carolina, Michigan, Wisconsin and Vermont.

Preventing Maple Tree Diseases

The best thing you can do for your trees to protect them from maple tree diseases is to take good care of them before they develop a disease. That means water regularly, fertilize annually, keep the area around the trees clean prune when necessary and seek help immediately if you notice your tree looking ill or having problems.