HOST STATUS OF CROTALARIA-JUNCEA, SESAMUM-INDICUM, DOLICHOS-LABLAB, AND ELYMUS-GLAUCUS TO MELOIDOGYNE-JAVANICA

Reproduction of Meloidogyne javanica on Crotalaria juncea PI 207657 an d cv. Tropic Sun, Sesamum indicum, Dolichos lablab, and Elymus glaucus was assessed using a root-gall index, a reproductive index obtained b y dividing the final population of juveniles (J2) in soil by the initi al J2 population (Pf/Pi), and the number of J2 per gram of root recove red from roots by mist chamber extraction. Lycopersicon esculentum (cv . UC 204 C) was included as a susceptible host. The root-gall index an d soil reproductive index were poor indicators of the host status of o ur test plants as compared with mist chamber extraction of J2 from roo ts. Lycopersicon esculentum had a mean root-gall index of 7.8. Some pl ants of S. indicum and E. glaucus had a few galls and other plants had none, with mean root-gall indices of 1.6 and 0.8, respectively. No ga lls were observed in C. juncea and D. lablab. Lycopersicon esculentum had the highest mean soil Pf/Pi value (mean = 1.93), while in C. junce a and some replicates of S. indicum no soil J2 were found. Even though some replicates had-no galls, all replicates supported nematode repro duction. The mean numbers of J2 per gram root after 5 days of mist ext raction were 447.7, 223.3, 165.5, 96.9, 42.3, and 41.9 for D. lablab, L. esculentum, E. glaucus, S. indicum, and C. juncea PI 207657 and cv. Tropic Sun, respectively. Accurate assessment of nematode resistance was influenced by sampling time and the nematode extraction technique used. Individual plants of both C. junicea and S. indicum supported ne matode reproduction to some extent; however, both C. juncea and S. ind icum have potential as cover crops to reduce M. javanica numbers.