POTENTIAL SOURCES IN STRAWBERRY FOR RESISTANCE TO BACTERIAL ANGULAR LEAFSPOT

Authors: Maas, John; Hartung, John; Hokanson, Stan

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: The bacterium Xanthomonas fragariae causes an economically important disease, bacterial angular leafspot, of strawberry that can reduce fruit yields in production fields through leaf infection, make fruit unmarketable when fruit is affected, and kill young plants transplanted into new production fields. There is no adequate chemical control for this disease and all commercial strawberry varieties are susceptible to the disease. We evaluated 81 strawberry types, commercial and native plants, for resistance to angular leafspot and found that two plants were resistant to the disease. These plants are close relatives to the commercial strawberry and can be used directly in a breeding program for developing new varieties resistant to angular leafspot. Successful incorporation of resistance and development of new resistant varieties will economically benefit growers. This information will be used by plant geneticists and breeders of commercial strawberry varieties.

Technical Abstract: Bacterial angular leafspot disease (BALD) of strawberry (Fragaria species and F. x ananassa Duchesne cultivars) has become increasingly important to strawberry fruit and plant production in Canada and the United States, as well as in other countries. Since this disease, caused by Xanthomonas fragariae Kennedy and King, was first documented from Minnesota in 1960, it has become of worldwide concern because of the economic importance of BALD in strawberry fruit and nursery-plant production and lack of adequate disease control strategies. Several attempts have been made in the past to identify sources of resistance to BALD; however, none of these studies were successful. We tested 81 Fragaria genotypes, including representatives of F. ananassa, F. chiloensis (L.) Duchesne, F. virginiana Duchesne, and F. vesca L., for resistance to two pathogenic strains of X. fragariae. Two genotypes, a native F. virginiana from Minnesota and a seedling of an F. virginiana parent from Georgia crossed with F. ananassa `Earliglow', were found to show hypersensitive-like reactions to both bacterial strains and are considered potential sources of resistance to X. fragariae.