Fungal diseases can be a common occurrence in trees. The presence of microscopic fungal spores and an ideal combination of warm, wet weather and wind can rapidly promote the growth of diseases. Much like the many tree variations, there are may tree fungal diseases. While each species has its own resistance to disease, some tree fungal diseases are quite common for all trees.
Anthracnose is caused by a group of varying fungi that collectively infect the tree. This leaf disease generally targets trees but will also infect grass, fruit and vegetables. Trees that are infected with anthracnose will develop dark-colored spots on the foliage. The leaves of the tree will also experience curling, distortion and necrosis. Severely infected trees will also experience early defoliation of mature and newly developed leaves. The anthracnose fungus lies dormant in defoliated debris under the tree. The potential for anthracnose is greatly reduced with the prompt removal of fallen debris. Copper-based fungicidal treatments are effective in controlling this disease.
Powdery mildew is a cosmetic disease that can result in injury of the tree. The disease develops as a covering of small white fungal spots that travel onto the tree through microscopic fungal spores. As the disease progresses, the spots coalesce into a powdery white covering of fungus. Present mainly on the foliage of the tree, the covering prevents the penetration of sunlight and slowly inhibits the tree from producing nutrients. Severely infected foliage will develop dark-colored decay, distortion, leaf curl, yellowing and eventual defoliation. The powdery coating is easily rinsed away with a steady flow of water. Control and prevention of the disease require a fungicidal treatment.
The soil-borne fungus that causes verticillium wilt can thrive for many years in the soil without a hosting tree. Attacking most woody and herbaceous trees, the disease causes the death of interior tissues and cells that are responsible for transporting nutrients and water throughout the tree. Death of the tree is almost certain when infected with this disease. There is no fungicidal treatment and most trees will require removal once infected.
Root rot is a widespread disease that infects many woody species. This fungal disease is especially present during long periods of continuously moist soil and warm temperatures. This soil-borne disease infects the root system of the tree, causing decay of the system and eventual collapse. Infected trees will show signs that include early defoliation, wilt, leaf curl and loose or decayed bark. Infected trees may also grow some fungal mushrooms near the base of the trunk. There are many fungal variations of root rot. Severely infected trees must be removed and discarded. Some mild root rot cases can be controlled with fungicidal sprays.