Discula destructiva

Dogwood Anthracnose Disease - Discula destructiva Redlin
 

Leaf damage

Flower damage

Tree damage

Dogwood anthracnose disease
Flowering and Pacific dogwoods (Cornus florida and C. nuttallii) are important components of the forest understory, as well as being valued for their natural beauty. Dogwood fruits are a valuable food source for migratory birds and mammals, and the twigs are browsed by a variety of animals (Mitchell et al., 1988; Rossell et al., 2001). In addition, the species provides habitat for nesting birds, and fallen leaves provide a significant amount of calcium to forest soils (Hepting, 1971).

Both dogwood species are being extirpated from North American forests by a relatively new exotic fungal disease, dogwood anthracnose. This disease is migrating through eastern and western forests and killing entire dogwood populations (Britton, 1993; USDA Forest Service, 1999). The disease was discovered almost simultaneously in Washington (1976) and New York (1978) (Daughtery & Hibben, 1994). The fungus is particularly virulent in cool, moist conditions, and dogwood populations near water are at the greatest risk. Trees are killed by annual cankers that girdle the trunk. Areas subjected to acid rain may predispose dogwoods to attack and increase the severity of the disease (Anderson et al., 1993). In flowering dogwood, there are surviving trees in populations that have been severely damaged, and natural resistance has been detected (Windham et al., 1998). To date, there have been no reports of putative resistant Pacific dogwoods.

Sources
Anderson, R. L., P. Berrang, J. Knighten, K. A. Lawton, and K. O. Britten. 1993. Pretreating dogwood seedlings with simulated acidic precipitation increases dogwood anthracnose symptoms in greenhouse-laboratory trials. Can. J. For. Res. 23: 55-58.

Britton, K. O. 1993. Anthracnose infection of dogwood seedlings exposed to natural inoculum in western North Carolina. Plant Dis. 77: 34-37.

Daughtery, M. L., and C. R. Hibben. 1994. Dogwood anthracnose - a new disease threatens 2 native Cornus species. Ann. Rev. Phytopath. 32: 61-73.

Hepting, G. 1971. Disease of forest and shade trees of the United States. United States Department of Agriculture, Forest Service Agricultural Handbook No. 386. 658 pages.

Mitchell, W., P. Gibbs, and C. Martin. 1988. Flowering dogwood (Cornus florida): Section 7.5.9., U.S. Army Corps of Engineers Wildlife Resource Management Manual, Tech. Report EL-88-9, U.S. Army Engineer Waterways Exp. Sta., Vicksburg, MS. 25 pages.

Rossell, I. M., C. R. Rossell, K. J. Hining, and R. L. Anderson. 2001. Impacts of dogwood anthracnose (Discula destructiva Redlin) on the fruits of flowering dogwood (Cornus florida L.): implications for wildlife. Amer. Midland Naturalist 146: 379-387.

United States Department of Agriculture Forest Service, Southern Region, Forest Health Protection. 1999. Southern forest health atlas of insects and diseases. USDA Forest Service, R8-MR 35. 20 pp.

Windham, M. T., E. T. Graham, W. T. Witte, J. L. Knighten, and R. N. Trigiano. 1998. Cornus florida 'Appalachian Spring': a white flowering dogwood resistant to dogwood anthracnose. HortSci. 33: 1265-1267.