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William G. Gonzalez and William L. Summers

233 tomato accessions of the Central American tomato collection maintained at CATIE and 7 commercial cultivars were evaluated for resistance to 4 virulent strains of Pseudomonas solanacearum representing race 1 biovars 1 and 3. In general biovar 3 strains wilted seedlings faster than biovar 1 strains but by 20 days post inoculation no significant differences were noted in susceptible check ratings. Highly significant differences for disease index were noted but no line with complete resistance was found. Two CATIE accessions, 17334 and 17340, were found to be as resistant as Hawaii 7998 to all 4 strains. Accessions 17345 and MIP-CH1 were resistant to 3 strains.

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William G. Gonzalez and William L. Summers

Seven tomato lines and their 21 hybrid populations were evaluated for their ability to resist infection by 7 virulent strains of Pseudomonas solanacearum representing race 1 biovars 1 and 3. In all cases the Gardner and Eberhart model III analysis found GCA values to be significant. In 5 of 7 cases SCA was significant. In 4 cases the parent vs. cross contrast was significant. We conclude that resistance to Pseudomonas solanacearum is predominantly controlled by additive gene action and to a lesser degree by dominant gene effects. Hawaii 7998 was found to be resistant to all 7 strains, while Rotam 4 and Rodade were resistant to biovar 3 and one race of biovar 1 (UW 275). Venus and Saturn were resistant to 3 other biovar 1 strains. Hawaii 7998 transmitted disease resistance better than the other resistant parents but its small fruit size and indeterminate growth habit make it a poor choice for a hybrid parent.

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William G. González and William L. Summers

Seven tomato Lycopersicon esculentum lines, `Venus', `Saturn', `Rodade', `Rotam 4', `Hawaii 7998', `UC-82B', and `Stevens', and their 21 crosses were evaluated for their ability to resist infection by seven virulent strains of Pseudomonas solanacearum E.F. Sm. representing race 1 biovars 1 and 3. The Gardner and Eberhart model III analysis was used to evaluate the response of lines in crosses to P. solunaceurum infection. General combining ability mean squares were significant for all strains and in 5 of 7 instances specific combining ability mean squares were significant. In four instances the parent vs. cross contrast was significant. `Hawaii 7998' was resistant to all seven strains of P. solanacearum, whereas `Rotam 4' and `Rodade' were resistant to biovar 3 and two races of biovar 1. `Venus' and `Saturn' were resistant to two other biovar 1 strains. `Hawaii 7998' transmitted greater resistance than the other resistant parents, but its small fruit size and indeterminate growth habit make it a poor choice for a hybrid parent.