F.J. Lawrence, G.J. Galletta, and D.H. Scott
D.O. Chellemi, H.A. Dankers, S.M. Olson, N.C. Hodge, and J.W. Scott
Several procedures for evaluating the resistance of tomato (Lycopersicon esculentum Mill.) to bacterial wilt were used to account for diversity in strains of Pseudomonas solanacearum Smith and to approximate resistance under field conditions. Five strains of P. solanacearum from Florida and one from North Carolina were inoculated onto 19 tomato genotypes and one tomatillo (Physalis ixocarpa Brot.) genotype using a stem-puncture technique. Genotypes were also transplanted as seedlings into naturally infested soil. Resistance was evaluated by comparing the response of each genotype to the susceptible cultivars Bonny Best and Sunny. With the stem-puncture technique, the mean incidence of disease ranged from 30% with the strain from North Carolina to 94% with a strain from northern Florida. Significant differences in the resistance of genotypes and pathogenicity of strains were observed. However, no interaction between strain and genotype was observed. Using naturally infested soil, the mean incidence of disease was 51% and significant differences in the resistance of genotypes were also observed. Hawaii 7997, Hawaii 7998, and CRA 66 had the lowest incidence of disease, regardless of inoculation method. The results indicate that assessing pathogen diversity and using a combination of resistance screening techniques can facilitate the evaluation of many genotypes, account for potential regional variability in the pathogen, and differentiate levels of field resistance to tomato bacterial wilt.
J.W. Scott, S.M. Olson, H.H. Bryan, J.A. Bartz, D.N. Maynard, and P.J. Stoffella
`Solar Fire' is a heat-tolerant hybrid tomato (Solanum lycopersicum L. formerly Lycopersicon esculentum Mill.) with resistance to all three races of Fusarium wilt incited by Fusarium oxysporum f. sp. lycopersici Sacc. Snyder & Hansen. It has superior fruit-setting ability in comparison with most existing cultivars under high temperatures (>32 °C day/>21 °C night), and the fruit crack less under the rainy field conditions often present in the early fall Florida production season. Fla. 7776 is the pollen parent in `Solar Fire', providing much of the heat tolerance in this hybrid. It has large fruit-providing breeders with a parent to produce heat-tolerant hybrids with two heat-tolerant parents.