A Comparison Between Meloidogyne floridensis and M. incognita from California on Susceptible and Resistant Sweetpotato Cultivars

The reproduction and ability to cause root-galling of a California isolate of the peach root-knot nematode Meloidogyne floridensis was evaluated on seven sweetpotato (Ipomea batatas) cultivars and compared with an M. incognita race 3 and an M. incognita Mi-gene resistance-breaking isolate. The susceptible tomato (Solanum lycopersicum) cultivar Daniela and the Mi-gene-carrying resistant cultivar Celebrity were included as controls. Repeated trials were done in pots in a nematode-quarantine greenhouse at the University of California, Riverside. The three Meloidogyne isolates reproduced equally well on susceptible tomato. On Mi-gene resistant tomato, the reproduction and root-galling by M. floridensis was intermediate between the avirulent M. incognita race 3 and the resistance-breaking M. incognita isolate. The sweetpotato cultivars 'Beauregard' and 'Diane' were excellent hosts for all three Meloidogyne isolates. Cultivars Bellevue, Burgundy, and Covington were resistant to these isolates. The cultivars Bonita and Murasaki-29 were hosts for the M. floridensis and the resistance-breaking M. incognita isolate, which allowed an increase in nematode levels, but they were poor hosts, resulting in a decrease in nematode levels for the M. incognita race 3 isolate. The study showed that M. floridensis can reproduce on tomato and some sweetpotato cultivars that are considered resistant to M. incognita.