The primary criterion for designating resistance and susceptibility of the accessions was the root gall severity index. Egg mass data was also presented because it provides additional information about the reaction of the accessions to Meloidogyne arenaria race 1. However, accessions were considered resistant only if both the root gall index and the egg mass index were <= 4.9. 'Charleston Gray', 'Crimson Sweet', and 'Dixie Lee' were included as susceptible check cultivars in all tests. Only one C. lanatus var. lanatus accession, PI 459074, could be classified as low resistance [root gall index (GI) = 4.9 and egg mass index (EMI) = 3.10]. All C. colocynthis accessions were highly susceptible (GI range = 8.5 to 9.0 and EMI range = 5.00 to 9.00). Twenty C. lanatus var. citroides accessions appeared moderately resistant with a GI = 3.1 to 4.0, but none were highly resistant.">WATERMELON.ROOTKNOT.NEMATODE.2003