METHOD: Visual Examination CONDITIONS: Growth Chamber - 16h light, 18-20C METHOD NARR: Plants were grown for 4 weeks before detaching a leaflet to be used immediately in screening test. Each isolate of P. infestans was applied s after inoculation the leaflets were examined with a dissecting scope to determine percentage of area affected and sporulation rating. RESULTS NARR: A 0-3 rating scale was used where 0 = no sporulation, 1 = light sporulati3 = heavy sporulation. Percent colonized = mean percentage leaflet necrotic and/or supporting sporulation. AUTHOR EXPLANATION: The presence of differential responses to isolates may indicate the presence of R-genes. Furthere the presence of hypersensitive flecks observed on susceptible leaflets. Heterogeneity within PIs was observed.