Utility of Mi Gene Resistance in Tomato to Manage Meloidogyne javanica in North Florida.

Three field trials were conducted to determine response of Meloidogyne javanica to tomato cultivars containing the Mi gene for resistance in sequential tests. Trials were conducted in spring and fall 1997 and spring 1998 on the same site. Tomatoes were grown on polyethylene mulch at a site initially treated with methyl bromide and then infested with M. javanica via drip tubing. Cultivars with the Mi gene were 'PSR 8991994' and 'Sanibel', and susceptible cultivars were 'Colonial' and 'Agriset 761'. The resistant cultivars greatly suppressed root galling in the three tests. Population densities of second-stage juveniles also were low in soil samples collected from resistant cultivars. Tomato fruit yields were significantly increased in only one test when using resistant cultivars. However, the susceptible cultivars are high-yielding and recommended for north Florida production, while the cultivars containing the Mi gene are not as well adapted. In the three successive crops, no evidence of resistance-breaking biotypes of M. javanica was observed. With further incorporation into adapted cultivars, the Mi gene resistance could be a valuable tool to manage M. javanica in north Florida stake tomato production.