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Thirty-three tomato (Lycopersicon esculentum Mill.) or L. pimpinellifolium (L.) Mill. accessions were inoculated with race T2 of Xanthomonas campestris pv. vesicatoria (Xcv) in a field experiment at Wooster, Ohio, in Summer 1995. These included accessions selected for race T2 resistance in greenhouse tests in Florida, and accessions from Hawaii, Brazil, and Bulgaria. One L. esculentum (PI 114490-1-1) and three L. pimpinellifolium (PI 340905-S1, PI 128216-T2, and LA 442-1-BK) accessions had no Xcv symptoms. This is the first report of resistance to Xcv race T2. Partial resistance was found in PI 271385, PI 79532-S1, PI 155372-S1, PI 195002, and PI 126428. Most of the 33 genotypes were tested for race T1 resistance in Presidente Prudente, Sao Paulo, Brazil in summer 1993. Hawaii 7983, PI 155372-S1, PI 114490, PI 114490-S1, and PI 262173 had greater resistance 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 from it.

Hawaii 7998 (foliage resistant to bacterial spot) was crossed with ‘Walter’ (susceptible) and F1, backcross, and F2 generations were derived. These genotypes were grown in the field at Bradenton, Fla. in the summers of 1984 and 1985 and inoculated with Xanthomonas campestris pv. vesicatoria, the incitant of bacterial spot. Disease severity for respective genotypes was similar both years, although somewhat greater in 1985. Disease severity in the F1 was intermediate to the parents, but slightly skewed toward resistance both years. The percentage of F2 plants with resistance comparable to Hawaii 7988 was 9.6% in 1984 and 4.6% in 1985. There was no evidence of cytoplasmic inheritance from three sets of reciprocal crosses tested in 1985. The data fit an additive-dominance genetic model, but dominance variance was negative both years, which indicates a small or negligible dominance effect. The negative dominance variance resulted in biased estimates of additive variance, narrow-sense heritability, and the number of effective factors. Nevertheless, narrow-sense heritability was moderate to high. When incorporating this resistance into new genetic backgrounds, we suggest that a modified backcrossing scheme with rigorous disease screening be used to obtain plants from homozygous resistant BCF3 lines before crossing.