Among diseases that attack oat (Avena sativa) crop, crown rust, caused by Puccinia coronata f. sp. avenae, has been the most destructive, being responsible for a decrease in the quality and yield of grains. Control through qualitative resistance has been restricted by the capacity of the pathogen to overcome this resistance type. Seeking an alternative strategy for disease control, 31 white oat genotypes were investigated for the occurrence of quantitative resistance. Trials were accomplished from 1996 to 2000, in the Agronomic Experimental Station of UFRGS, in Eldorado do Sul, RS, Brazil. Disease progress was evaluated in the field for three years, and some genotypes were tested for five years. Weekly evaluations of rust severity in each plot were performed, providing data from which to determine the disease progress curves, and calculate the area under the disease progress curve (AUDPC), and the rate of development of disease (r). There was great variability among genotypes for all the years in regard to rust reaction, allowing the genotypes to be classified in four groups: resistant, moderately resistant, moderately susceptible and susceptible. The first two groups have good levels of quantitative resistance and can be used in the future as parents in breeding programs.
