Dogwood Anthracnose Diagnostic Guide
Dogwood anthracnose, Discula destructiva, can be a devastating disease of flowering dogwoods in the eastern United States, and Pacific dogwood in the Pacific Northwest. Although most infections occur on landscape trees, it can also be found on native dogwoods in natural areas. Symptoms are most visible during rainy, cool spring weather.
Trees at Risk
Mostly flowering and Pacific dogwoods. Kousa dogwood is also susceptible, but the effect of the disease is usually limited to leaf spotting.
Signs of Damage
- Rounded, blotchy leaf spots with tan centers and purplish borders.
- Shriveled, dead leaves are often seen hanging from infected branches.
- Symptoms develop first on lower branches and progress upward.
- Epicormic shoots or water sprouts.
- Discolored, sometimes sunken, cankers may develop on infected twigs causing girdling and twig death.
During spring rainy weather, dogwood anthracnose spores are splashed onto new shoots, leaves, and flowers resulting in shoot blight and leaf spots.
The management of dogwood anthracnose is most successful when a combination of plant health and chemical controls are used. For plants with extensive damage (more than 50% of the plant is symptomatic), removal may be the most cost effective solution. Plant health practices include planting resistant varieties of dogwood to reduce the risk of dogwood anthracnose, as well as watering and mulching to reduce plant stress. It is important, however, that watering does not get the leaves or shoots wet as this is likely to make the infection worse. During rainy springs, fungicide sprays can protect new shoots and leaves on high-value dogwoods. Begin sprays when the buds open and reapply 1 to 2 more times at 14-day intervals. Fungal diseases will always be present, so the goal is suppression of the symptoms, not complete eradication of the disease.
A Diagnostic Guide is designed to help you identify a pest issue and management solutions. Always refer to product label for all rates and approved uses. Some images courtesy forestryimages.org. Use of the images does not imply endorsement of treatments by forestryimages.org