Quantitative Evaluation of Resistance of Korean Tomato Cultivars to Isolates of Phytophthora capsici from Different Geographic Areas. Jae Soon Hwang, Graduate Student, Department of Agricultural Biology, Korea University, Seoul 136-701. Byung Kook Hwang, Professor, Department of Agricultural Biology, Korea University, Seoul 136-701. Plant Dis. 77:1256-1259. Accepted for publication 31 August 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-1256.

The resistance of 10 Korean tomato cultivars to seven isolates of Phytophthora capsici was evaluated by using stem wounding and foliar spraying methods under controlled environmental conditions. The response of tomato cultivars tested to Phytophthora blight was quantitative rather than qualitative. There were highly significant differences among the isolates in virulence to the Korean tomato cultivars, indicating some pathogenic variation in P. capsici. Significant differences were also observed among cultivar × isolate interactions in the analysis of variance. When the inoculation was by stem wounding, no symptoms developed in the stems of mature tomato plants. Expression of the age-related resistance to Phytophthora blight was more apparent in tomato stems than in tomato leaves. The foliar spraying inoculation method was effective in screening tomato cultivars for resistance to P. capsici, whereas the soil drenching and stem wounding inoculation techniques were less reliable for evaluating cultivar resistance on old tomato plants.