The role of mixed cropping systems on bean root rot epidemics in south western Uganda

Abstract

In south western Uganda, beans are largely grown as intercrops with sorghum, maize, sweet potato and potato . Continuous cropping of beans, has increased bean root rot epidemics. Since some of the root rot causing organisms are known to affect other crops, there was need to investigate the role they may be playing in the current root rot epidemics. Surveys were carried out in Kabale district in order to establish the incidence of root rot on other crops grown in association with beans. Plant samples for isolation of Pythium, the main causative agent of root rot were also collected. Results indicated that potato had a high root rot incidence while maize had a low root rot incidence. Also, sorghum and peas had root rot symptoms. Out of the 142 Pythium isolates collected, 21 different Pythium species were identified by ITS-DNA sequencing. Fifteen new Pythium species not previously identified in the region were found. This study finds evidence that diverse crop species associated with beans may be playing a role in bean root rot epidemics