Residue management and overwinter survival in winter canola (Brassica napus L.)

Winter canola production in eastern Canada is a growing segment of the Canadian canola industry. Crop establishment and survival overwinter have been identified as two of the major challenges associated with the production of winter canola. Environmental conditions can interact with agronomic practices, including seeding date, plant population density, fertility and residue management, to influence stand establishment in autumn and overwinter survival. The objective of the current research was to evaluate the impact and interaction of preceding crop residue and tillage practices on the establishment, overwinter survival and yield of winter canola in southern Ontario. Winter canola was seeded following either winter wheat or soybean and using conventional, no-till or strip-till practices. Over the course of the three years of study, the annual decline in winter canola plant population density was influenced by the type of tillage practice used but not by the preceding crop. The overwinter decrease in plant population density was largest in no-till, followed by strip-till and finally conventional tillage. At physiological maturity, winter canola yields in reduced tillage practices (i.e., no-till and strip-till) were equivalent to those achieved utilizing conventional tillage practices. When grain yields were standardized as a function of the spring plant population density, the highest and lowest yield per plant coincided with the lowest and highest plant population densities and were observed in strip-till (14.2 g plant-1) and no-till (9.1 g plant-1), respectively. Results of this research have established that winter canola can be successfully produced in Ontario utilizing a range of tillage practices.