INFLUENCE OF CULTIVAR, INOCULUM DENSITY AND PLANT AGE ON THE INCIDENCE OF FUSARIUM ROOT AND STEM ROT IN COWPEA

Abstract

This study was undertaken to determine the effect of host genotype, inoculum density and plant age on the severity of Fusarium root and stem rot in cowpea (Vigna unguiculata). Different levels of Fusarium solani inoculum, namely: 8 x 104, 2 x 10 6 and 4 x 108 conidia/mL were inoculated to 5-, 17- and 22-day old seedlings of TVX 289-4G, VCS 6-1 and CES 42-2 cowpea cultivars. Among the cultivars tested, CES 42-2 was the most resistant since it exhibited a lower degree of infection in contrast to VCS 6-1 and TVX 289-4G. The degree of infection was not significantly affected by the different levels of inoculum used. However, plant age significantly affected the percentage of infected plants. Fusarium root and stem rot infection was higher in 22- than in 17-day old plants, and was completely suppressed in 5-day old seedlings. Significant interaction effects of inoculum density, cultivar and plant age as well as their combinations on disease severity were noted.