3 Things Gardeners Need To Know About Oak Anthracnose

Planting oak trees in your backyard can help create an appealing environment, but these trees can develop diseases that impact their appearance and health. Once of these diseases is oak anthracnose; here are three things gardeners need to know about oak anthracnose. 

How do trees get oak anthracnose?

Oak anthracnose is caused by Colletotrichum or Gloeosporium fungi, types of fungi that live in the soil. These fungi can be spread to new areas when diseased trees shed their leaves and these leaves are blown to new areas. The fungi can then overwinter in these diseased leaves, and when it starts to rain in the spring, the fungi will enter the soil in their new location.

What are the signs of oak anthracnose?

If your oak tree develops this disease, you'll notice that there are cankers on its branches. Cankers are dead areas on the tree. These dead areas may be indented, swollen, or a different color than the rest of the tree.

Oak anthracnose also causes lesions on the leaves of affected trees. You'll notice that your oak's leaves have yellow or brown spots on them that aren't associated with a chance of seasons. These spots may have a sunken appearance.

Trees that are severely affected may repeatedly lose their leaves, and this reduces their resources. Trees in this condition will be more at risk of being attacked by destructive insects, like beetles. If your oak trees are infested with insects, oak anthracnose may be to blame.

Can oak anthracnose be treated?

It's hard to control oak anthracnose. Fortunately, the disease doesn't usually cause serious damage to affected trees, explains the Minnesota Department of Natural Resources. In the Great Lakes region, the disease is usually more severe due to climatic conditions, and in this region, affected trees may be heavily affected.

If your trees are already infected, you can take steps to help it recover. Have the trees trimmed by an arborist to promote good air flow around the trees' leaves. You should also ensure that your trees receive an appropriate amount of water to keep them from becoming stressed. In dry conditions, mulch or watering the trees can provide necessary moisture, while in wet conditions, creating a good drainage system can protect the trees from excess moisture.

Preventative treatment is the best way to control this disease. In the spring when your oak trees start producing leaves, spray the trees with fungicide. This treatment needs to be done two to four times to ensure the tree is protected. You may be able to treat a small tree by yourself, but for large trees, it's a good idea to hire an arborist to handle the treatment. Once the tree is infected, spraying it with fungicides won't help, so it's important to take this step before the leaves appear.

If your oak trees have cankers or lesions on their leaves, seek the advice of an arborist (such as one from http://nwresidentialarborist.com/).