Advances in the selection of resistance sources to important diseases common bean (Phaseolus vulgaris L.) in Costa Rica.
In this research a broad set of bean genotypes were evaluated in the search for sources of resistance to both, anthracnose (Colletotrichum lindemuthianum) and angular leaf spot (Pahaeoisriopsis griseola). The germplasm evaluated came from the National Bean Breeding Program and international nurseries from CIAT: VIFURE, VIPADOGEN and CORE COLLECTION. Experimental plots were establised in Puriscal (1017 masl), Alajuela (814 masl) and Fraijanes (1650 masl), during the 97-98 and 98-99 growing seasons. Experimental plots were single or two rows from two to six m in length depending on seed availability. Disease reaction was scored at six and eight weeks after seeding using a 1 to 9 severity scale. Only genotypes showing 1-3 disease reaction for anthracnose and 1-4 for angular leaf spot were selected. In the germplas from the National Bean Breeding Program nine lines resistant to both pathogens were identified, of those, five lines were specifically resistant to anthracnose and two angular leaf spot. In the VIPADOGEN from CIAT, 25 lines were resistant to anthracnose and only two were resistant to both diseases. These materials also displayed adaptation to either drought or low soil fertility. The CORE COLLECTION nursery provided 82 lines resistant to anthracnose, 12 lines resistant to angular leaf spot and 26 lines were resistant to both pathogens. The most outstanding sources of resistance to anthracnose and angular leaf spot will be made available in a regional nursery.