Effects of Intercropping and Cultivar Mixtures on Bean Diseases and Yield

Abstract

The effects of bean intercropping with maize and bean cultivar mixtures on bean angular leaf spot (ALS), rust, floury leaf spot (FLS) and yield were studied for two seasons in Jimma in split plot design with three replications. Intercropping did not significantly (P =
0.05) affect bean diseases or yield. Moreover, no interaction effect between intercropping and cultivar mixtures for all the parameters was observed. However, cultivar mixture significantly (P = 0.05) reduced area under the disease progress curve (AUDPC) and disease severity index (Dl) of ALS and rust on the susceptible component of the mixture; but did not significantly affect that of FLS. Cultivar mixture reduced ALS AUDPC and Dl by 1 to 27% and 2 to 31%, respectively, and rust AUDPC and Dl by 13 to 30% and 9 to 28%, respectively, on the susceptible cultivar. Generally, disease development decreased as the proportion of resistant cultivar in the mixture increased. Yield of the two cultivars was higher in mixtures than in their corresponding pure stands. In mixtures, Browns peckled gave 5 to 26% more yield than its pure stand and ICA15541 gave 11 to 33% higher yield than its pure stand. The results reflect the possible use of bean cultivar mixtures to reduce bean ALS and rust and increase yield.