Submitted to: Potato Association of America Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 10, 2000
Publication Date: N/A
Late blight is the most important fungal disease of potato worldwide. Since this fungus is able to rapidly overcome major race-specific resistance genes, breeding for more durable resistance has become a high priority. Quantitative resistance of foliage to late blight was evaluated in a diploid potato F1 population grown in field trials in PA during 1999. A cross between a highly resistant and a highly susceptible diploid clone resulted in 240 F1 progeny. The two parents and three control cv. (Atlantic, Kennebec and Kathadin) were included. The experimental design was a randomized complete block with two replications. A mixture of three isolates of P. infestans, clonal lineage US-8, was used to inoculate spreader rows. Percent defoliation was estimated visually in each plot four times during the season and area under disease progress curve (AUDPC) was calculated. AUDPC ranged from 67 to 1000, with an overall mean of 610 and a standard deviation of 205. The observed distribution was skewed towards higher AUDPC values. There were significant differences between replications and among clones. The nature of the distribution suggests that resistance to late blight in this diploid population is quantitative.