Comparative whitefly vector density and bean disease incidence on local and hybrid varieties in semi-arid Kenya

The dry bean, Phaseolus vulgaris (L.) production is constrained by various factors in the environment. A survey was carried out to determine incidence of various foliage diseases and possible influence by whitefly vectors among other environmental factors on bean grain yield. Highest farmer cultivar preference was a tie of improved KAT Bean 1 (B1) and local cultivar (Mwitemia) at 24% as total of each category. Production level was 0.3-1.6 t ha-1 per farm. Dominant whitefly species was Bemisia tabaci (Genn.) in over 90% of the farms. Laboratory analyses showed that disease incidence among the varieties showed improved varieties bearing highest incidence of both fungal and viral diseases compared to the local cultivars. Disease incidence showed little influence on bean grain yield. The updated information here is useful to breeding programmes to focus on local cultivars for higher disease-tolerant bean genotypes.