Pythium / Rhizoctonia complex causing damping-off of cowpea in South Africa

Pythium ultimum and Rhizoctonia solani were consistently isolated from cowpea seedlings with symptoms of damping-off in South Africa. Isolates of the two species were tested individually and in combination for their effect on cowpea seedlings in the greenhouse at 20, 26 and 32 °C. Damping-off induced by R. solani was the highest at 20 °C, and disease incidence decreased with increase in temperature. P. ultimum caused most disease at 26 °C and significantly less at 20 and 32 °C. Percentage damping-off induced by P. ultimum was higher than that induced by R. solaniat all three temperatures. Disease incidence incited by P. ultimum was significantly reduced by R. solani when the two fungi were combined, suggesting an antagonistic interaction between them.