Yield depression in cowpea cnltivars infected with Xanthomonas campestris pv. vignicola in Sudan savanna of Nigeria

Abstract

Two field trials were conducted in the Sudan savanna site of IITA Experimental Station, Minjibir, Kano State, Nigeria to assess the effect of bacterial blight on pod, grain and fodder yield of two cowpea varieties artificially inoculated with Xanthomonas campestris pv. vignicola. One hundred percent disease incidence was recorded in inoculated plants both in 1996 and 1997. High disease severity scores of 59 and 56 were recorded in inoculated IT82D-889, and 67 and 63 for inoculated IAR-48, in 1996 and 1997 respectively. In the 1996 trial, IAR-48 had depressions of 42%, 43% and 34% in pod, seed and fodder yields respectively. In the same year, pod, seed and fodder yields of IT82D-889 were depressed by 67%, 64% and 29%, respectively. In 1997, pod, seed and fodder yields of IAR-48 were depressed by 46%, 45% and 34%, respectively while in IT82D-889, higher depressions of 71.0%, 68.0% and 53.0% were recorded.