| Summary: | Root rots occur in all the zones where beans are cultivated in the world. Fusarium spp., Pythium spp., Rhizoctonia solani, Sclerotium rolfsii, and Macrophomina phaseoli are found among the responsable microorganisms. Each pathogen developes according to its own optimum conditions. Problems are greater under humid conditions, except for Sclerotium. At CIAT resistant materials are found, susceptible to be improved. The steps to follow in a breeding program are: (1) test promissory materials for each pathogen; (2) include these evaluations in the choice of parents; and (3) test progeny in advanced generations to recover a resistance equal or superior to that of the parents. Information on resistance trials on different var. are presented in table form. (CIAT)
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