Management of Meloidogyne incognita and other phytonematodes infecting Amaranthus cruentus and Telfairia occidentalis with African marigold (Tagetes erecta) and Siam weed (Chromolaena odorata)

Abstract

Field trials were conducted to investigate the effects of eight week-old seedlings of African marigold and siam weed applied as organic amendments on nematodes including Meloidogyne incognita, Helicotylenchus spp. and Dolichodorus spp. infesting Amaranthus cruentus and Telfairia occidentalis, and on leaf yield of M. incognita-infested A. cruentus and T. occidentalis. A nematode-infested plot without African marigold and siam weed served as control. There was significant reduction in population densities of M. incognita, Helicotylenchus spp. and Dolichodorus spp. in plots amended with seedlings of African marigold and siam weed compared to control treatment in both experiments. There was also a corresponding significant increase in the leaf yields of A. cruentus and T. occidentalis in the amended plots compared to control plots. The levels of total N, available P and exchangeable K increased with a decrease in pH at harvest in amended plots in both crops compared to control. The results of this study suggest that seedlings of eight week-old African marigold or siam weed incorporated into soil prior to planting has potentials to reduce plant-parasitic nematode population densities, increase soil fertility and enhance leaf yield of associated vegetable crops.