Reproduction of Two Races of Meloidogyne incognita in Tomato Plants Grown at High Temperature.

T h e effect of high soil t empera ture on resistance of tomato (Lycopersicon esculenturn Mill.) to Meloidogyne spp. has been repor ted by several authors (3,4,5). However, the susceptibility of tomato grown at high soil temperatures to different races o£ M. incognita (Kofoid and White) Chi twood has not been reported. This mat te r must be considered an impor tan t factor in a tomato screening program for resistance to root-knot nematodes. Al though there are four widespread races of M. incognita around the world (9), only two races were examined in this investigation. Nine tomato genotypes were inoculated with either race I or race 4 of M. incognita. T h e L. esculenlum genotypes were 'Floradade' (susceptible to M. incognita) and 'Nematex-22, ' 'Patriot , ' 'Piersol, ' '74T2, ' and the F1 o£ Floradade x Nematex-22 (resistant to M. incognita); the L. peruvianum var. dentatum Dun. accessions were PI129149-2(sib)-5-16 x 43, PI-129149-2(sib)-5-4, and PI 266376 (resistant to M. incognita). T w o races of M. incognita, each identified by host differential responses (6,7,8,9), were used as sources of inoculum. Race 1 was originally collected f rom tobacco (Nicotiana tabacum L.) in Gilchrist County, Florida, and race 4 was collected f rom tomato in Manatee County, Florida. Both populat ions were main ta ined on Floradade