Mixture of Colletotrichum lindemuthianum races in anthracnose resistance screening and its implication for common bean breeding

Evaluations by artificial inoculation of different races of Colletotrichum lindemuthianum can be unfeasible in a breeding program aiming at obtaining cultivars with durable resistance to anthracnose in common bean, since many physiological races have already been found. An alternative would be the use of mixtures of different races. However, information is scarce about the efficiency of this method to select resistant plants and to evaluate the virulence of the pathogen. Thus, the objective of this work was to demonstrate the feasibility of using mixtures of C. lindemuthianum races in breeding programs aiming at the development of common bean cultivars with resistance to anthracnose. Two experiments were carried out, in which races 65, 73 and 81 of C. lindemuthianum were inoculated individually and in a mixture of the three races (M1), and also mixtures of first (M2 and M3) and second (M4, M5, M6 and M7) generations, for cultivars Pérola and BRSMG Majestoso. The use of mixtures of races of C. lindemuthianum was efficient in evaluating anthracnose severity and could be recommended as an alternative method to save costs and time.