Anthracnose is a common leaf spot disease that attacks many different tree species, especially ash, maples, and white oaks, during cool and wet weather of spring and early summer. Early symptoms of this disease may result in blotching, distortion, and large dead areas on the leaves often times in lower to middle sections of the canopy. When weather conditions favor disease development, leaf loss can occur. In severe cases, trees may lose the majority of their leaves.
This causes significant stress and can easily lead to more serious health problems such as Verticillium Wilt. When minor leaf loss occurs, control is usually not warranted. However, if significant leaf loss has occurred within the last two years, control measures are necessary. Foliar applications of a fungicide, beginning when new leaves are just emerging and at two week intervals, can provide excellent Anthracnose control.
Once the disease is present on the leaves, control measures become less effective. It is importnant to note that this spray program is designed to prevent significant leaf loss. It will not completely prevent all Anthracnose from occurring.
Recommendations for prevention and control:
- Prune trees regularly to improve air circulation
- Hire a professional ISA Certified Arborist(R) to evaluate the tree to idenitfy the disease and recommend proper treatment for control
- Sign up for fungicide treatment applications per your arborist's recommendation
- Fertilize to help improve overall health and vigor
- Provide adequate water, especially during dry periods or drought
- Rake up and dispose of any fallen, infected leaves