Preliminary Report on Fusarium oxysporum f. sp. lycopersici (Sensu lato) From Some Tomato Producing Agroecological Areas in Southwestern Nigeria and Susceptibility of F1-Resistant Tomato Hybrid (F1-Lindo) to Infection

Abstract

Aims: To isolate Fusarium oxysporum f.sp. lycopersici from infected tomato plants in selected tomato producing agroecological areas in Southwestern Nigeria and evaluate susceptibility of F1-resistant tomato hybrid (F1-Lindo) to infection, to understand the propensity of adopting the hybrid. Methodology: Seven F. oxysporum f.sp. lycopersici were isolated from infected tomato plants collected from some tomato producing agroecological areas in the Southwestern Nigeria. The isolates were identified using their morphological features and characterized based on growth, sporulation rates, lag-time and virulence. Growth rate was estimated using a linear model for estimation of fungal growth. Conidia of five of the isolates were standardized to 1.0 x 106 conidia/mland tested for virulence against Race-1-resistant tomato hybrid, F1-Lindo. Pathogenicity of the fungal isolates were ranked according to severity of damage to the tomato hybrid. Results: The growth, sporulation rates and the lag time of the isolates showed statistically significant difference, F (16, 4) =249.16, P=0.001. The isolate, ADO-1 had the slowest rate of growth (0.24 mm day-1), while ADO-2 had the fastest growth (1.6 mm day-1) among the seven isolates. The lag time of the isolates showed no statistically significant difference, F (6, 281.06) =0.98, P=0.479 and they were between 4.6 hours to 10.5 hours. Five of the isolates were tested for pathogenicity to tomato and the mean percentage damage recorded (53-61%) were not statistically different F (4, 40384.9) =1.993, P=0.98. Conclusion: The tomato hybrid, F1-Lindo was considered susceptible to the isolates and it was suggested that the isolates of F. oxysporum f. sp. lycopersici evaluated for virulence were probably other races to which F1-Lindo was susceptible.