The resistance of Hevea rubber tree genotypes to south american leaf blight was evaluated. Two isolates of Microcyclus ulei included in the stage I and II were used. Seedlings in polyetilene bags were inoculated in the B1/B2 growth state with 2 χ 10s conidia/ml. The plants were incubed in humid chamber for 24 hours at 24° C. The latent period (PL), lesion diameter (DL), lesion type (TL), and the reaction type (TR) were determined. The major of genotypes were complete susceptible to at least one isolated of the pathogen. The genotypes that showed moderate resistance to one isolate, generally were suscetible to the other. Only the AM/86/271 genotype showed incomplete resistance characterized by larger PL, small DL and low sporulation, although the number of isolates tested do not warrant the resistance type. Based in these results we concluded that the genotypes tested do not have perspectives to be used in a breeding program for resistance to M.ulei.
Microcyclus ulei; Rubber tree; Hevea; Resistance