| Sumario: | A total of 103 varieties of the common bean, collected from all over the American Continent, were tested in regard to their susceptibility to the fungus Fusarium oxysporum f. phaseoli. The results obtained clearly demonstrate that none of the varieties tested was truly resistant to the attack of the fungus, since the latter could be reisolated from all infected plants. Thus one can speak only of a certain degree of tolerance. However, several varieties tolerant to the conidial stage were susceptible to the chamydospore stage. A certain correlation between seed color and tolerance was found: light colored varieties were practically all very susceptible, whereas the highest degree of tolerance toward conidia was found among the red colored ones (28%). The same fungus could either produce intense yellowing, wilting without loss of pigmentation, or stunting according to the variety. Bean plants that produced a large number of strong lateral roots after infection proved more tolerant.
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