This disclosure concerns methods and compositions for identifying canola plants that have a blackleg resistant phenotype. Some embodiments concern molecular markers to identify, select, and/or construct blackleg resistant plants and germplasm, or to identify and counter-select plants that are susceptible or have low resistance to blackleg disease. Some embodiments concern molecular markers to identify, select, and/or construct blackleg resistant plants that carry the rlm4 gene. This disclosure also concerns canola plants comprising a blackleg resistant phenotype that are generated by methods utilizing at least one marker described herein.