Use of green manure plants in cropping systems to suppress root-knot nematodes

Abstract

Green manure plants namely Calliandra calothyrsus, Canavalia ensiformis, Chenopodium quinoa, Crotalaria juncea, Desmodium uncinartum, Gliricidia sepium, Leucaena leucocephala, Mucuna pruriens, Tephrosia purpurea, Tithonia diversifolia and Vicia villosa were evaluated to determine their reaction to Meloidogyne javanica. Sesbania sesban and Tagetes minuta were included as susceptible and resistant checks respectively. In the glasshouse, pots were filled with steam-sterilized soil, sown with the green manure plant, and then infested with 4,000 eggs and juveniles of M. javanica. Field experiments were conducted in plots infested with a mixed population of M. javanica and M. incognita. Crotalaria juncea, D. uncinartum, G. sepium, L. leucocephala, M. pruriens, T. diversifolia and T. minuta had galling and eggmass indices lower than 2 and reduced nematode populations by up to 80%. Calliandra calothyrsus, C. quinoa and C. ensiformis had galling indices lower than 4 and eggmass indices less than 3.2. Vicia villosa and T. purpurea were susceptible with galling indices greater than 7 and nematode population buildup of up to 500%. Chenopodium quinoa, C. juncea, D. uncinartum, G. sepium, L. leucocephala, M. pruriens and T. diversifolia are suppressive to root-knot nematodes and can therefore be recommended as rotation, fallow or cover crops.