Oak Anthracnose

Oak wilt is responsible for the demise of thousands of oak trees in Austin, Texas over the past several years. It affects all species of oaks, although outcomes for each may vary. Because the outcome generally includes an affected tree’s demise, it is best to take preventative measures to avoid the disease altogether. However, if you find that any of your landscaping oaks appear to be affected, it is important to know that there are several tree diseases whose symptoms are similar to that of oak wilt. This is a critical because even minute variations in symptoms may indicate a different diagnosis than that originally concluded. One such disease that may easily be mistaken as oak wilt is oak anthracnose.

Like oak wilt, oak anthracnose is also caused by a fungus, Apiognomonia quercinia. This fungus generally affects the buds, leaves, or twigs of the white oak species. Mature leaves tend to be more resistant to the disease. If an oak is affected, however, indicators include necrotic margins or necrotic, blackened (water-drenched) spots on the oak’s leaves. Often, the blackened spots are in peculiar shapes, and there is a defining margin between the diseased and healthy sections of the leaf. The most affected leaves tend to be misshapen.

There are some rather remarkable differences between oak wilt and oak anthracnose that may become more obviously recognized as the respective diseases progress. Consequently, these differences may be the best indicators leading to the correct and appropriate diagnosis of the affected tree.

Perhaps the most prominent of these differences is the affected species of oak. Although oak wilt can affect all species of oak, it most predominantly affects red oaks. On the other hand, oak anthracnose most predominantly affects white oaks.

Strategic locations of the first noted signs of disease also vary between the two. Signs of oak wilt typically manifest on the extremities of the tree near the canopy. Signs of oak anthracnose typically manifest on the lower and inside area of the tree. This is the area of the tree where humidity is highest.

Perhaps the most notable difference between the two diseases is this. Once exposed to oak wilt, a tree has very little chance of survival. Prevention of the disease is the best bet. Concerning oak anthracnose, however, a tree’s chances of survival are greater. Although the loss of leaves and sometimes twigs may cause the tree to be less visually appealing than a completely full and healthy tree, the damage caused by oak anthracnose is generally not permanent. The effects can be controlled. Such control methods include the raking of dead, moist leaves during the fall and winter months and appropriate pruning of dead or dying branches. Depending upon the size of the tree, pruning may be possible if the affected branches are accessible without the need for heavy equipment and if you are knowledgeable in applying appropriate pruning techniques. If you are not knowledgeable in such techniques or if the affected branches are not accessible due to overall size or cause safety hazards, contact an Austin tree trimming specialist for professional assistance in trimming your oaks.

If you suspect a landscaping oak is affected by either oak wilt or oak anthracnose, contact a professional Austin tree care service for assistance in the appropriate diagnosis and treatment.

About the Author: Andrew Johnson is the owner of Central Texas Tree Care, a leading provider of Austin tree service in Central Texas. Certified ISA Austin arborist services including: tree trimming, tree removal, tree care and oak wilt treatment. For more information on Austin tree service, please visit https://www.centraltexastreecare.com.

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