Interaction of Meloidogyne javanica and Rhizoctonia solani on cowpea

Abstract

The effect of Meloidogyne javanica (Treub) Chitw. and Rhizoctonia solani Kuhn, singly and in combination, on the growth of cowpea [Vigna unguiculata (L.) Walp] was evaluated in a greenhouse experiment. Three soil types were used: sand (pure fine sand); sandy loam (66, 19 and 15 per cent respectively of sand, silt and clay); and loamy sand (84,6 and 10 per cent respectively of sand, silt and clay). The soil was autoclaved before filling 15 cm clay pots in each of which four cowpea cv. HFC 42-1 seeds were sown. Three days after germination each pot was thinned to one plant and four days later inoculated with M. javanica (1000 juveniles/plant) and/or R. solani (2 g mycelial mat) in the root zone. Inoculated and uninoculated controls were also maintained. Each treatment was replicated four times. Plant shoot length, shoot dry weight and root dry weight were decreased in all treatments compared with the uninoculated control. Only root dry weight was significantly reduced. However, plant growth was better in loamy sand than in the other two soil types for all the treatments. The reduction in number of nodules compared with control was nonsignificant in all the treatments. Loamy sand supported the greatest number of nodules and hence the better plant growth. The simultaneous inoculation of fungus and nematode inhibited the nematode multiplication since number of galls were less in this treatment compared with the inoculated control (nematode alone).