Resistance to Dogwood Anthracnose among Cornus Species

Abstract

Dogwood anthracnose caused by Discula destructiva poses a threat to flowering {Cornus florida) and Chinese (C. kousa) dogwood in the eastern United States and to Pacific or western dogwood (C. nutallii) in the Pacific Northwest. Differences exist in the impact the pathogen has on these hosts (subjectively in the order C. florida > C. kousa and C. nutallii). Ten Cornus species, including C. alternifolia, C. amomum, C. controversa, C. alba, C. augustata, C. florida, C. kousa, C. mas, C. sericea, and C. stolonifera, were evaluated for disease reaction in 1991 and 1992 at locations in eastern Tennessee infested with D. destructiva. Greatest disease severity in 1991 was observed on C. controversa, C. florida, C. kousa cv 'Chinensis', and C. sericea. In 1992, C. florida, C. sericea, C. kousa cv 'Chinensis', C. alba, and C. stolonifera cultivars appeared susceptible to anthracnose. Symptoms developing on each appeared similar to those observed on flowering dogwood, and D. destructiva was successfully isolated from lesions within the canopy of the trees. Other Cornus species tested, including an unnamed Chinese dogwood cultivar, appeared resistant. The results of this study indicate that concerns regarding the anthracnose susceptibility of native and ornamental Cornus species may be raised. Finally, the possibility should be considered that infected Cornus species (other than C. florida) might serve as a mechanism for the introduction of D. destructiva into anthracnosefree areas of the United States.