A new methodology of inoculating Uromyces appendiculatus in tests aimed at evaluation of common bean resistance to rust is proposed. The common bean lines Golden Gate Wax (gene Ur-6) and Ouro Negro (gene Ur-ON) were crossed to obtain a F2 population, which was inoculated with race 29-3 of U. appendiculatus. Race 29-3 is incompatible with 'Ouro Negro' and compatible with 'Golden Gate Wax'. Primary leaves of ten-days-old F2 plants were detached and inoculated by immersion into an inoculum suspension. Immediately following immersion, each F2 leaf was placed in a Petri dish containing a filter paper previously moistened with distilled water. These dishes were incubated in a BOD at 20ºC, under a 12h daily light regime. The humidity in the dishes was maintained by addiction of 1.5 mL of distilled water in filter paper, under a three days regime. As control, the remaining primary leaves of ten-days-old F2 plants were inoculated using the conventional inoculation method. Both inoculation methods were efficient in evaluating the reaction of the common bean to U. appendiculatus. The resistance/susceptibility screening of the F2 population confirmed the monogenic dominant nature of the rust resistance controlled by the Ur-ON gene in both methods.
common bean rust; inoculation method; Phaseolus vulgaris; resistance screening
