Brassica vegetable leaf residues as promising biofumigants for the control of root knot nematode, Meloidogyne incognita infecting cowpea

Abstract: Under screenhouse conditions , two mashed leaves of plants belonging to the genus Brassica, cabbage (Brassica oleracea var. Capitata L.) and kohlrabi (Brassica caulorapa L.) were used as pre-and at sowing biofumigants at 20g/pot for managing root knot nematode, Meloidogyne incognita on cowpea (Vigna unguiculata (L.) Walp)compared to metam potassium and metam sodium as chemical biofumigants as well as untreated check. It was found that, in general, there was a positive correlation between the time of the addition of the plant residue (10 and 5 days before sowing and at sowing time) and the percentage final nematode population reduction i.e., the highest percentages final nematode reduction (70.4 and 82.1%) oc­curred when Brassica oleracea and B. caulorapa residues were added, 10 days before sowing, respectively compared to those (61.9 and 61.1%) occurred after the respective residues were added at sowing time. Also, plant growth and yield(pods and seeds) criteria of cowpea plants behaved the same trend