Submitted to: American Journal of Potato Research
Publication Type: Proceedings
Publication Acceptance Date: March 6, 2009
Publication Date: June 1, 2010
Citation: Haynes, K.G., Thill, C., Bradeen, J., Secor, G., Vales, M., Christ, B., Douches, D. 2010. Resistance to Late blight in Potato Clones Evaluated at Five U.S. Locations in 2008. American Journal of Potato Research. 87:127.
Late blight (LB), caused by Phytophthora infestans, continues to be a major disease of potatoes. In 2008, 40 potato clones (4 varieties, 32 selections, 4 LB differentials) were evaluated for foliar LB at five U.S. locations (MI, MN, ND, OR, PA) to allow for evaluation under environmental and pathogen diversity in a randomized complete block design with 3-4 replications per location. Multiple strains of P. infestans were present across locations, although U.S.-8 predominated. Percent infected foliage was recorded several times following onset of the disease. Area under the disease progress curve (AUDPC) was calculated. Location mean AUDPC ranged from 377 in PA to 917 in MN. There were significant differences among clones for AUDPC at all locations. Three advanced selections (A97066-42LB, MSQ070-1, W6360-1Rus) were as resistant as the resistant standard clones (AWN86514-2, B0692-4, B0718-3). Clones were ranked for mean AUDPC within locations and analyzed for phenotypic stability using nonparametric statistics. There was a significant clone x location interaction for the common variance of the ranks but only one clone (MSL268-D) made a significant contribution to this interaction. MSL268-D was one of the most resistant clones in MI and PA, but one of the more susceptible clones in MN and OR. The foliar reaction of most of these clones to P. infestans was stable across locations in the presence of multiple strains of P. infestans (poster, Breeding, PAA membership137).