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Of 467 accessions of Capsicum pepper (Capsicum annuum L.) tested for resistance to gray leaf spot, KC321, KC220, KC208, KC47 (PI244670), KC43 (PI244670), KC380, and KC319 were highly resistant to both Stemphylium solani and S. lycopersici, the causal agents of gray leaf spot. Gray leaf spot, caused by Stemphylium solani Weber, was first reported on tomatoes by Weber (1930) in Florida. Hannon and Weber (1955) found that another closely related spe- cies of Stemphylium also caused gray leaf spot on tomatoes (Lycopersicon esculentum Mill.), symptoms of which were indistinguishable from those caused by S. solani. They named this new species S. floridanum; its current name is Stemphylium lycopersici (Enjoji) Yamamoto (Ellis and Gibson, 1975). Both S. solani and S. lycopersici are also pathogenic on pepper (Hannon and Weber, 1955; Weber, 1930). Gray leaf spot on pepper caused by S. solani was first observed in a natural field condition in Louisiana by Sinclair et al. (1958) and later in Florida by Blazquez (1969), but its occurrence on pepper caused by S. lycopersici has not been reported previously. We have observed severe leaf spot and defoliation on pepper plants caused by gray leaf spot in Korea since 1994. The disease was more prevalent on plants growing in relatively cool mountainous terrain, such as Subi-Myun, Youngyang in Kyungpook province. Two dif- ferent species of Stemphylium were isolated from the diseased leaves, depending on the specimen collected. The causal fungi were identified as Stemphylium solani and S. lycopersici, respectively (Cho, 1997). Studies on resistance to the disease have been conducted since 1996 in a wide range of genetic resources. Good levels of resistance have been observed and the results are re- ported here.

Bacterial wilt caused by Ralstonia solanacearum is sporadically causing damage to pepper in Korea. We put efforts in analyzing the genetics of resistance to bacterial wilt and in subsequent breeding for resistance by selection. Two Korean cultivars, Subi and Chilsung, were crossed with a resistant source, MC-4, which was kindly provided by Lopes in Brazil. In addition, four breeding lines bred for resistance to Phytophthora blight were crossed with another resistance source, PBC631, which we received from AVRDC. F2 and backcross populations of the crosses were developed and tested by inoculation by dipping the roots of the seedlings before transplanting 25 days after seeding. Segregation in the F2 and backcross populations did not fit any mode of simple Mendelian inheritance, but appeared inheriting in a quantitative mode with relatively low heritability. Selection was practiced in the subsequent F3, BC1F2, F4, and BC1F3 generations and a few resistant selections were obtained.