Resistance components and the growth of Xanthomonas campestris pv. vesicatoria (Xcv) were quantified on resistant ('Ohio 8245', 'Agrocica 30' and 'Hawaii 7998') and susceptible ('CNPH 401-08' and 'CNPH 416.81.01.02') tomato (Lycopersicon esculentum) genotypes. The bacterial population increased differently on resistant and susceptible groups of genotypes and it was about 100 times higher in the susceptible genotype 'CNPH 401-08', seven days after inoculation. The resistance components evaluated were lesion size, number of lesions, lesion area, and latent period. All the components of resistance were statistically different in resistant and susceptible genotypes, except for lesion size, which discriminated only 'CNPH 416.81.01.02' from resistant genotypes. The latent period varied from six to 11 days in susceptible and resistant genotypes when assessed in the field, greenhouse, and growth chamber. Lesion number and latent period were considered reliable components for evaluating resistance to bacterial spot, in contrast to lesion size, which was unstable and very dependent on environmental conditions.
latent period; size of lesions; number of lesions; infected area; Lycopersicon esculentum
