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.
Treatment Strategy
The management of dogwood anthracnose is most successful when a combination of cultural and chemical controls is used. For plants with extensive damage (more than 50% of the plant is symptomatic), removal may be the most cost effective solution. Cultural 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.
Other Treatment Practices
- Clean up and destroy fallen leaves and twigs.
- Prune trees or shrubs to open up canopy for better air circulation and light penetration if applicable.
- Reduce moisture on foliage from sprinklers, but maintain proper irrigation, especially through extended periods of drought.
- Cultural practices including:
- Using an air spade to alleviate soil compaction
- Mulching
- Adding organic matter to improve soil health
Foliar Spray Using Myclotect
Foliar Spray Using Pegasus 6L
Foliar Spray Using Talaris 4.5F
Expected Results
Anthracnose will always be present in the landscape, and treatment must focus on suppression, not eradication.
DO NOT APPLY CAMBISTAT TO CORNUS SPECIES.
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
Photo: Robert L. Anderson
USDA Forest Service, Bugwood.org
Photo: Robert L. Anderson
USDA Forest Service, Bugwood.org
Trees At Risk
- Mostly flowering (Cornus florida) and Pacific dogwoods (C. nuttallii)
- Kousa dogwood (C. kousa) is also susceptible, but the effect of the disease is usually limited to leaf spotting
Biology
- During spring rainy weather, dogwood anthracnose spores are splashed onto new shoots, leaves, and flowers resulting in shoot blight and leaf spots.
References
University of Massachusetts
https://ag.umass.edu/landscape/fact-sheets/dogwood-anthracnose
Diseases of Trees and Shrubs – Sinclair and Lyon
Always refer to product label for rates and approved uses. Some images courtesy of forestryimages.org or Wikimedia Commons. Use of the images does not imply endorsement of treatments.
