RESISTANCE TO RACE T2 OF THE BACTERIAL SPOT PATHOGEN IN TOMATO

Thirty-two tomato (Lycopersicon esculentum Mill.) or L. pimpinellifoli um (L.) Mill. accessions were inoculated with race T2 of Xanthomonas c ampestris pv. vesicatoria (Xcv) in a field experiment in Wooster, Ohio , in 1995. Plants from accessions which segregated for race T2 resista nce in greenhouse tests were selected and these are designed by hyphen ated extensions below. The eight most resistant accessions from 1995 a nd PI 262173 were retested in 1996. Lycopersicon esculentum accession PI 114490-1-1 had virtually no Xcv symptoms either year. Lycopersicon pimpinellifolium accessions La 442-1-Bk and PI 128216-T2 expressed a h igh level of resistance in 1995, but only partial resistance in 1996. Accessions with partial resistance for both seasons were PI 79532-S1, PI 155372-S1, PI 126428, PI 271385, PI 195002, PI 262173, Hawaii 7998, and Hawaii 7983. PI 79532-S1 is a L. pimpinellifolium accession and t he remaining seven are L. esculentum. Twenty accessions tested in 1995 for T2 plus 10 other accessions were also tested for race T1 resistan ce in Presidente Prudente, Sao Paulo, Brazil, in 1993. Hawaii 7983, PI 155372-S1, PI 114490, PI 114490-S1, and PI 262173 had greater resista nce to T1 than the susceptible control, 'Solar Set'. Comparisons with earlier experiments, in which accessions were inoculated with race T1 or T3, indicated that the most consistent source of resistance to all three races was PI 114490 or selections derived from it.