- Misshapen leaves
- Irregular leaf spots
- Spots have irregular edges
Infection of young leaves results in dead, deformed margins and irregularly shaped, purple-edged dead spots. These spots form along the veins or are confined by them. Heavily infected leaves may appear misshapen and curled. Tan fruiting bodies scattered within the lesions are small and difficult to see. Severe infections may result in leaf drop. Dogwood anthracnose symptoms are heaviest in the lower branches of the tree where relative humidity is highest and leaves remain wet. Cankers (stem infections), most commonly found at the base of dead twigs, girdle the branch and cause dieback. If not pruned out, the canker can spread to larger branches or to the trunk. Dogwood anthracnose can be distinguished from other anthracnose diseases affecting dogwood by the large lesion size (dime size or larger) and the lack of black fruiting bodies.
Discula destructiva is the most devastating anthracnose pathogen of dogwood. The fungus primarily overwinters in cankers on infected branches and twigs, but can also survive in fallen leaves. Wind carries spores from the cankers to developing leaf and twig tissue in the spring. Infected leaves may shrivel and fall, while infected young twigs can be girdled and killed. Infections on water sprouts or suckers can travel back to the trunk very quickly, often killing the tree. Warm, wet weather promotes infection.
Proper watering, mulching, and sanitation will reduce damage caused by dogwood anthracnose. Raking leaves in the fall and pruning dead or dying branches helps reduce the number of new infections the following year. Trees should be pruned only during dry weather. Fertilize severely stressed trees, but only in the spring. Trees that have been severely stressed from repeated defoliation, or are newly transplanted, may benefit from chemical control. Fungicide application should begin at bud break to protect new growth. Repeat applications according to the fungicide label during cool wet weather. Read the label carefully and apply only as directed.
Active Ingredients include: Chlorothalonil, Myclobutanil, Thiophanate-methyl
