Evaluation location: Michigan, United States
Visual Examination CONDITIONS: Green House - Inoculation tent with RH above 90% and 18-25C METHOD NARR: Plants were placed in the inoculation tent and inoculated using a hand-held sprayer. Disease severity was estimated as the percentage of stem and leaf area with symptoms of late blight at 7 and 14 days after inoculation. Severity values were rated up to 4 weeks after inoculation. RESULTS NARR: Mexican accessions were more resistant to late blight than the Russian and South American accessions. There was a high range of variability found within all accessions and genotypes with good levels of resistance found in the Russian hybrids and SA species. AUTHOR EXPLANATION: While the Mexican accessions showed higher resistance, they are somewhat difficult to introgress into cultivated potato. There were genotypes of the South American and Russian Hybrid populations that showed moderate resistance. These specific genotypes may prove to be more useful in developing late-blight-resistant cultivars. Mcd, scr and ber were the best candidates for introgression.