the main goal of this study was to assess the nature and magnitude of gene effects for resistance to cercospora leaf spot. a randomized block design with three replications was used. the data were obtained at the plant level by assessing the disease severity. the data were analyzed per experiment, using the average data per plot. a dominant-additive genetic model without epistasis was considered, with estimation of the components of means and variance. the genetic control of resistance to gray leaf spot is polygenic with predominance of the additive effects. dominance was observed in a few small-effect loci and high heritability values.