Oak Tree Diseases- Home

Oak Tree Diseases

While many people love the majestic beauty of having an oak tree in their yard, they are vulnerable to a number of oak tree diseases. Home owners should be aware of these and watch for any symptoms to ensure they are properly treated before they cause serious damage or even the death of the tree.


Anthracnose has a tendency to effect the white oak family more than common types of oak. This is one of the oak tree diseases in which symptoms are usually first seen in the early part of the summer. The obvious sign is brown spotting which appears in an irregular pattern covering the majority of the leaf usually around the veins and midribs. You may also notice the texture changing to become more papery. As the growing season progresses these patches develop into dark pustules caused by the fungus of the disease.

Hypoxylon Canker

Hypoxylon Canker becomes more evident initially as a dieback of at least one branch. The diseased limbs foliage becomes dry and yellow and this dieback can spread between the branches until it causes the death of the tree. It can take several years for the tree to be killed by the disease depending on the trees exposure to stress and the environment it lives in. Around the time of death the bark will peel off and a great number of dusty brown spores will be exposed. These disappear within a month and the surface becomes grey and covered with fruiting structures which are numerous and black. When these structures mature they can discharge fungus spores up to a distance of two feet. These can then infect surrounding trees through injured surfaces to continue infestation.

Powdery Mildew

Powdery Mildew affects any members of the oak tree family. An infected leaf will have faint indistinct spots on the surface of the upper leaf with a white powdery growth underneath the leaf. It is more commonly seen in late fall. Powdery Mildew is one of the oak tree diseases which very rarely affect a single tree. It is more common in groups of trees where air circulation is reduced.


Actinopelte Leafspot is a disease which is more common in the red oak family and can also infect white oaks. Symptoms include small reddish brown spots which are at their most severe towards the end of summer and beginning of fall. It tends to attack younger trees rather than older more established oaks and can cause a severe defoliation effect.


Physalospora Twig Blight can cause infected trees to appear as if they have been attacked by insects of cicada. There are also brown leafs attached to dead shoots. This fungus disease attacks through wounds in the twigs and will eventually kill the twig and the attached branches. Although it can cause noticeable damage to the tree, it rarely kills the entire tree.

Oak Wilt

Oak Wilt is the most dangerous of the oak tree diseases. It can affect all members of the oak family. The most noticeable symptom is a brown necrotic effect on the veins of the leaves. The remaining area of leaf may continue to be green or may turn yellowish. There may also be a large amount of dropped green leaves. After infection occurs, this disease can kill the tree either very rapidly, in the case of red oaks, or very slowly such as in white oaks.
Oaks are beautiful trees but they are vulnerable to a number of oak tree diseases. If you think your oak tree may be showing signs of disease, seek professional advice as early treatment may be essential in saving the life of the tree. Often simple pruning can eliminate the infection but to be effective an accurate diagnosis is needed.