Relative resistance of six cowpea cultivars as affected by the concomitance of two nematodes and a fungus

Abstract

Cowpea cultivars that were resistant or moderately resistant against individual pathogens lost their resistance in the presence of the other pathogens except cv. lC-503 (moderately resistant to Meloidogyne incognita). Cv. S-488 (resistant to Rotylenchulus reni/ormis) did not remain resistant in the presence of M. incognita though it did not lose its resistance in the presence of Rhizoctonia solani. Similarly, the resistance of cv. CO-4 to R. solani broke down in the presence of M. incognita but not in the presence of R. reni/ormis. Both R. reni/ormis and M. incognita, when present in association with R. solani, broke the resistance of cv. lC-244 against R. solani. The moderately resistant response of cvs. RC-8 and EC-4213A to R. reni/ormis and their complete resistance against R. solani broke down when simultaneously inoculated with both the nematode species or R. solani with either R. reni/ormis or M. incognita.