What is a Fungal Infection on a Tree?

Fungal infections can sometimes take hold of trees. While not all types of trees are susceptible to fungal infections, many are. Tree fungus can range from relatively harmless varieties to those that are fatal to trees. Tree fungus is often detected by the appearance of fungal disease, which can vary depending upon the type of fungus. 

How do trees contract a fungal infection?

Similar to how fungus takes hold anywhere, it moves and reproduces through the dispersion of spores. Spores can be spread by wind and rain or by animals, such as birds and insects. In some circumstances, spores can infect a tree after contaminated gardening tools have been used. For this reason, many arborists recommend disinfecting tools after use. This step can prevent some fungal infections. Although since spores can spread due to environmental conditions, not all infections can be prevented.

Exposure to spores doesn’t necessarily result in a fungal infection. Similar to humans, trees have a natural immune system to protect themselves. Healthy trees are much more likely to ward off a potential fungal infection than those that do not get enough water or sunlight. 

What are the signs of a fungal infection?

Many tree owners might question what a fungal infection looks like or what signs indicate that a tree has been infected. Generally speaking, fungal infections may result in discolorations, irregularities in the bark, or wiling in the leaves. In some infections, you might be able to visually see the fungus as it can appear as a light dusting or coating on the tree. In advanced cases of fungal infection, you will see portions of the tree die-off or go dry during the growing season. 

While these signs are general signals that an infection may be present, certain types of fungal infections have distinct signs based upon the type of fungus that has infected the tree. Some of the more common varieties include:

• Anthracnose: Anthracnose infections are prevalent in dogwood trees. This fungus can cause tan or brown spots to appear on the tree’s berries while the leaves wilt. 
• Sooty Mold: This type of fungus is rarely fatal for a tree, but it does deprive them of sunlight. The leaves of the tree will also have form a black film. 
• Verticillium Wilt: This type of fungal infection can be fatal, impacting a wide variety of trees. The leaves of infected trees will curl, yellow, and dry out. Unfortunately, there is no remedy for verticillium wilt, and trees that become infected will die. 
• Dutch Elm Disease: This type of fungus inhibits a tree’s ability to circulate water and nutrients. Infected trees will demonstrate leaves that curl, drop, wilt, and yellow. It is usually fatal to the tree. 
• Apple Canker: Canker infections often develop knots or abnormal growths on a tree’s limbs. This type of infection may also cause sunken spots within the bark. 
• Armillaria Root Rot: Root rot is a bit different from other fungal infections and can be caused by several types of fungi. In many instances, you may be able to see mushrooms at the base of the tree visually. However, the tree will also experience yellowing and wilting leaves and stunted growth. 
• Powdery Mildew: In this type of fungal infection, the fungus attacks the leaves directly, making them appear to have a light dusting of powder. Because of its appearance, this type of infection is one of the easiest to detect. Fortunately, it is not fatal. 
• Oak Wilt: Oak wilt is fatal. It commonly causes wilting and browning out of season. The leaves of infected trees will also drop. Because this fungus spreads through the root systems, infected trees should be removed as soon as an infection is identified. 
• Shot Hold Fungus: Shot hole fungus causes leaves to develop blotches and holes, similar to damage caused by insects. 
• Cercospora Leaf Spot: This type of infection is characterized by brown circles surrounded by tan blotches. The infection interferes with the tree’s ability to photosynthesize. 

While many fungal infections are not fatal to the tree, all types of infections can harm the tree’s health. In many instances, prevention of fungal infections can save you a ton of time and money trying to save trees. The risk of fungal infection can be greatly reduced by:

• Ensuring the tree gets the proper amount of water, sunlight, and fertilizer.  
• Removing dead leaves and debris from around the tree.
• Preventing overwatering of the trees.
• Sanitizing gardening tools
• Employing fungicides, when appropriate.

Contact Tree Barber today if you suspect one of your trees may have a fungal infection or want to learn more about fungal infections and disease control. Our experts can arm you with the information and resources you need to keep your trees safe.