Influence of different cropping systems on incidence and severity of bacterial pustule of cowpea (Vigna unguiculata (L) Walp) caused by Xanthomonas campestris p.v. vignicola (Burkholder) dye

Abstract

A study was undertaken to determine the influence of growing cowpea under three different cultivation practices on bacterial pustule development in the field. The disease spread within and between plants was shown to be least when cowpea were grown as a relay crop after maize during the long rains and when grown as an intercrop with maize during the short rains. During the short rains, disease incidence increased to 62.5% in cowpea maize intercrop, 75.0% in cowpea pure stand and 91.25% in cowpea‐maize relay crop after forty days from inoculation. During the long rains, disease incidence increased to 68.75% in cowpea‐maize relay crop, 100% in cowpea pure stand and 100% in cowpea‐maize intercrop after sixteen days inoculation. The different disease levels in the relay crops is attributed to the different weather that these crops received as they were planted at the end of the rainy season when maize had matured. Disease severity also had the same development as disease incidence.