The bacterial wilt caused by Ralstonia solanacearum is the most important bacterial disease of tomato in the Brazilian North Region. The objectives of this study were to evaluate (1) the resistance level of ten tomato cultivars; (2) the progress of bacterial wilt in these genotypes in order to know the disease behavior in different stages of development of the crop, and (3) determine the critical time to disease development in these cultivars, in Roraima. The experiment was carried out in a field naturally infested with biovar 1 of R. solanacearum, during two years. The area was infested by cultivating susceptible tomato plants to bacterial wilt. The cvs. Majestade, Nemonetta, Carmen, Liliane, Santa Clara, Sensação, San Vito, Gaúcho Melhorado, Hector and Laura were cultivated in the infested field. Six disease incidence evaluations were done in seven plants with irreversible wilt and/or death during the crop cycle. The following variables were determined: area under the disease progress curve (AUPDC) and the progress rate (r), mean incidence (Y50), maximum incidence (Ymax) and the final incidence of the disease. The values of AUDPC and the variable r to 'Majestade' were the lowest, although the level of resistance shown by this cultivar was not very high. Therefore, 'Majestade' is recommended for planting in the State of Roraima, especially considering the high prices of tomatoes, which are purchased from other regions in the country. However, only the level of resistance of 'Majestade' is not sufficient for disease control, being necessary other control measures.
Solanum lycopersicum; Ralstonia solanacearum; area under the disease progress curve; rate of development of disease
