Breeding for resistance and integrated management of web blight in common bean

Abstract

AbstractCommon bean (Phaseolus vulgaris L.) production in the humid tropics may increase if less predictable rainfall becomes a serious seed yield constraint in traditional areas of production. The successful production of common bean will require the effective management of common bean diseases favored by hot and humid conditions. Web blight (WB), caused by Thanatephorus cucumeris (Frank) Donk, is a serious disease of common bean in the humid tropics causing significant losses in both seed yield and seed quality. At present, only moderate levels of WB resistance have been identified. Leaf and seed damage and leaf lesion size are criteria that have been successfully used to screen common bean genotypes for WB resistance in the greenhouse and in the field. Pedigree selection has been successfully used to develop cultivars having moderate levels of resistance. Recurrent selection has been used to broaden the genetic base and to produce progeny having higher levels of WB resistance. Sources of resistance from secondary gene pools should be used to combine resistance genes from diverse sources. Common bean cultivars with earlier maturity, deep tap roots, and terminal drought tolerance may be desirable traits for farmers who plant later in the wet season to avoid WB. Seed production during the dry season using irrigation would help to reduce infection of the seed and transmission of the WB pathogen. Minimum tillage techniques are useful to help to reduce the spread of the disease. Biological control may contribute to the management of WB and complement genetic resistance.