Reproduction and biology of Scutellonema bradys in roots of tropical cover crops
Keywords:Aeschynomene, Mucuna, nematode life cycle, nematode management, Puraria, Tagetes, yam nematode
AbstractOne of the options for the management of Scutellonema bradys on yam is the use of non-host cover crops. This study evaluated the ability of S. bradys to infect and reproduce in the roots of selected cover crops. Two pot trials were set up to compare infection and reproduction in 10 cover crops to a known susceptible control in a completely randomized design (CRD) with five replicates. Plants were inoculated with 2,000 S. bradys 2 wk after planting. Fresh shoot and root weight, number of nematodes in roots and soil, and reproductive factor (RF) of the nematode were taken at 12 wk after planting. A second experiment was set up in a CRD with three replications using the same crops and inoculated with 500 adult S. bradys. Plants were harvested daily for 45 d. The roots from each harvested plant were stained in lactogylcerol and observed for stages of nematodes present. Tagetes erecta, Stylosanthes guianensis, Centrosema pubescens, Pueraria phaseoloides, Aeschynomene histrix, and Mucuna pruriens were designated as poor hosts based on significant (P ≤ 0.05) reduction of S. bradys populations in their roots and an RF < 1. Also, these cover crops lengthened or terminated the life cycle of S. bradys. Cajanus cajan was regarded as a trap crop because it supported initial nematode penetration but hindered reproduction of S. bradys. However, Lablab purpureus, Crotalaria ochroleuca, and C. juncea were good hosts and similar to the susceptible Vigna unguiculata in their ability to support infection and reproduction of S. bradys. Cover crops that negatively affect the development and life cycle of S. bradys have the potential to reduce damage from S. bradys in yam-based cropping systems.