Survival Of The Yam Nematode, Scutellonema bradys In Soil And Roots Of Some Weed Hosts Between The Yam Growing Seasons
AbstractThe ability of Scutellonema bradys to survive between yam growing seasons on roots of weeds and in soil was evaluated. S. bradys-infected yam setts were planted in an infested field (Plot A), healthy setts were
planted in an infested field (Plot B) and an uninfested field (Plot C). Monthly soil samples were collected from each field for six months. Seeds from five weeds associated with yams were planted in sterilized soil
in pots. The plants, including a “no-weed” control were inoculated with 1000 nematodes; the control was not inoculated. The experiment was laid out in a randomized complete block design with four replications. The number of nematodes in roots and soil was taken and total number of nematodes and reproductive factor (RF) were computed. S. bradys was observed in soil collected from all the plots. Nematode populations in Plot C was significantly less than in Plot A and B. Commelina. benghalensis root and soil had a high (P≤0.05) nematode population and RF of 3.5, compared to Chromolaena odorata (0.7) and the other weeds including the no weed treatment (0.1). Weeds such as C. benghalaensis that multiply S.
bradys, and C. odorata that maintain low populations should be excluded in fields in which yams are to be planted. Populations of S. bradys can build up in rrots of some weed hosts in the absence of yams. S. bradys can also survive in low populations in soil even in the absence of its hosts, which can serve as inoculum for the next yam crop.