Submitted to: Potato Association of America Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 11, 2000
Publication Date: N/A
With the emergence of new and more aggressive strains of Phytophthora infestans and the release of new potato cultivars, an evaluation of potato clones for resistance to late blight is necessary. Thirty-nine potato clones (23 cultivars, 16 selections) were evaluated in 1999 for late blight resistance at six U.S. locations, along with eight late blight differentials. Among the 23 cultivars evaluated, 8 have been released within the past two years. Percent infected foliage was recorded at approximately weekly intervals following the onset of disease at each location. Clones were ranked for mean AUDPC within locations and analyzed for phenotypic stability using nonparametric statistics. There were significant genotype x environment interactions on the rankings of these clones across locations. The most late blight resistant clones were AWn86514-2, B0767-2, and A90586- 11. AUDPC was minimal in the late blight differentials LBR8 and LBR9 across all locations. As a group, the mean AUDPC of the eight newest cultivars was 880, compared to 925 for the nine most widely grown cultivars indicating some small gains are being made in improving late blight resistance in new cultivars.