THE EFFECT OF MIXED CROPPING ON THE SEVERITY OF LEAF BLIGHT ON SORGHUM (SORGHUM BICOLOR L.) AND MAIZE (ZEA MAYS) IN SWAZILAND

Abstract

Management of northern leaf blight caused by Exserohilum turcicum through planting patterns is important in reducing disease on susceptible cultivars. A study was conducted in 1995/96 growing season to evaluate the effect of mix-cropping resistant and susceptible sorghum and susceptible maize and susceptible sorghum in different proportions and arrangements on the severity of leaf blight at three locations in Swaziland. Mix-cropping maize and sorghum did not reduce severity of leaf blight on either crop. Mix-cropping reduced disease severity on susceptible sorghum that was mix-cropped with resistant sorghum, but the effect was dependent on the growth stage of sorghum. Different ratios of sorghum mixtures reduced disease severity. However, severity was not significantly different in most cases among different ratios and crop arrangement patterns. Locations differed significantly in disease severity depending on the stage of growth of sorghum. Location X treatment interaction was significant only at dough stage of growth of the sorghum crop. Mix-cropping resistant and susceptible sorghum cultivars can be used to reduce the severity of leaf blight on susceptible sorghum cultivars.


(UNISWA J Agric: 2000 9: 5-11)