Host Status of Melon, Carrot, and -susceptible and -resistant Cotton, Cowpea, Pepper, and Tomato for from California

The host status of carrot, melon, and susceptible and resistant cultivars of tomato, cotton, cowpea, and pepper for a California isolate of the peach root-knot nematode was determined in greenhouse pot experiments. It was compared to a race 3 isolate of . Melon was an excellent host for both isolates and roots were heavily galled after the 8-week trial. Carrot was a host for , but a poor host for , although both isolates caused similar levels of galling. Susceptible cotton was a good host for race 3, but a poor host for . Susceptible tomato, cowpea, and pepper were good hosts for both isolates. The resistance in tomato and pepper was broken by . Resistant cowpea was a maintenance host as population levels of remained virtually unchanged over the trial period. We conclude that poses a risk to some important vegetable crops in California, as it reproduces on most vegetable crops, including some cultivars that are resistant to . On susceptible crops, the reproduction of was always significantly less than that of , and we hypothesize that in mixed species field populations, will outcompete . This study demonstrates that efforts to limit the spread and prevent further introductions of in California are important to maintain the effectiveness of plant resistance as a nematode management strategy in vegetable crops.