Oak Tree

How to Treat Oak Tree Diseases?

There are several types of oak tree diseases that affect trees in the United States, such as actinopelte leaf spot, anthracnose, armillaria root rot, bacterial leaf scorch and more. In this article, we have described some of the most common diseases that affect oak trees and how to treat them.

As with most things, proper care is the best way to defend against any illness. Oak trees, just like other plants, flourish through proper watering, sunlight and good soil quality. Some of the best ways to keep oak tress healthy and stress-free include applying around 3-inch layer of organic mulch, applying weed killers, watering the tree during droughts, using slow-fertilizers in spring, protecting the tree and root system from damage and removing any diseased or damaged tree from the property using professional lawn care services, such as Eden.

Enjoy a beautifully manicured lawn with our timely yard work services that care for your yard according to the season. Call us today!

Still, if an oak tree in your yard contracts a disease, you don’t need to fret. Here are some of the common oak diseases and their treatments. You can identify most oak tree diseases by checking their leaves and trunks, looking for dead or damaged branches. 

1. Actinopelte leaf spot

Actinopelte leaf spot causes circular, dark or reddish-brown spots to form on the leaves. These can often join together and form blotches. Severe infection from this disease can cause premature leaf-shedding in the tree. 

This disease is usually caused by wet weather which increases the fungal growth. This disease can survive the cold temperatures of winter in infected twigs and leaves that cling to the tree. You can see the signs of infection emerging after the tree’s buds break

You can treat Actinopelte leaf spot in oak trees by removing all infected plant material, which slows the spread of infection. You should spray fungicide on small-sized trees that have lost their leaves for several years in a row. 

2. Anthracnose

Anthracnose causes dead areas to develop between leaf veins. This is usually seen in leaves on the lower branches of oak trees. You may notice brown spots forming on the lower leaf surface as well as on dead twigs

This oak tree disease is usually caused by cool, wet weather as it helps to incubate the fungus which is responsible for its spread. The spring and summer seasons are ideal for this infection to take hold. This fungal infection not only affects oak trees but various other plants and trees too.

The best way to treat anthracnose is by pruning dead twigs and branches during the tree’s dormancy period. In addition, you should also apply the proper fungicide to protect the new growth on the oak tree.

3. Armillaria root rot

The armillaria root rot causes honey-colored mushrooms to grow at the base of the tree, every year. These growths are seen in large clumps and are usually followed by a white fan of fungal growth right under the bark at the base of the oak tree. 

This infection is usually caused when the fungal spores are carried to the root of oak tree through soil, wet weather and improper drainage. This infection affects all varieties of oak trees, and the signs of infection are usually seen in late summer or early fall

The best way to treat armillaria root rot is to remove the infected tree and protect the healthy oak trees from stress. 

Oak tree

4. Bacterial leaf scorch

Bacterial leaf scorch causes the edges of old leaves to turn brown. This infection usually starts on the lower and inner portions of the oak tree. You may also notice a reddish band developing between the brown and green spots on the leaves and branches begin to die

This oak tree disease is usually caused by spittlebugs and grasshoppers that carry the xylella fastidiosa bacteria. The bacteria affect the tree’s water movement and causes dead spots to appear on leaves. This bacterial infection shows signs during late summer and early fall, usually after a drought in summer. This infection usually affects red, pin, white, single and bur oak varieties. 

The best way to treat bacterial leaf scorch is by applying oxytetracycline injections by professional lawn care experts, such as Eden. This will control the symptoms but you will eventually need to remove the infected oak tree to prevent the bacterial infection from spreading to other healthy oak trees around it 

5. Slime flux/Bacterial wet wood

Bacterial wetwood, also known as slime flux is an oak tree disease that causes dark streaks of sap to ooze from the tree’s bark. This sap usually has an unpleasant odor, which indicates to the presence of bacterial wetwood. 

This disease is caused by many varieties of bacteria if they enter the tree through a wound in the bark. Though pin oaks are most vulnerable, the bacteria can affect oak trees of all varieties. 

The best way to treat slime flux in an oak tree is by preventing new wounds on the bark. You should care for the oak tree as you normally do and try to minimize its stress as much as possible. 

6. Ganoderma root rot

Ganoderma root rot forms shelf-like growth on the wood, very near the soil line. These are usually brown to reddish growth. This disease causes the tree’s growth to slow down and the dying branches can only produce small yellow-colored leaves. 

This disease is caused by fungi-carrying spores that spread on the wind and lead to wood decay. Physical injury to the tree and drought conditions can exacerbate the risk of infection. Though all oak tree varieties are susceptible to this infection, you can reduce the risk with proper care.

The best way to treat ganoderma root rot is by removing the damaged oak tree, for safety purposes. This disease takes years to kill the tree, which makes it vulnerable to damage from high winds. 


Some of the most common oak tree diseases are the actinopelte root rot, anthracnose, armillaria root rot, bacterial leaf scorch, bacterial wetwood/slime flux and ganoderma root rot. You can try the treatment methods listed above to treat small to mild infections. On the other hand, if the oak tree disease is severe, it is highly recommended to call in professional lawn care experts, such as Eden for best results. 

Enjoy a beautifully manicured lawn with our timely yard work services that care for your yard according to the season. Call us today!