Integrating Cultural Practices with Herbicides Augments Weed Management in Flax

Flax (Linum usitatissimum L.) is an important crop with value in both food and industrial markets. However, flax competes poorly with weeds and as a result, flax yield can be severely inhibited by weed competition. Factors that favor crop competitive ability will have great value in improving weed management in flax. This research sought to identify different combinations of seeding date (early vs. late May), seeding rate (400 vs. 800 seeds m(-2)), cultivar height (short vs. tall), and herbicide (present vs. absent) that could improve the competitive ability of flax. Field studies were conducted across western Canada over 3 yr from 2014 to 2016. Results showed that seeding a tall cultivar at a high seeding rate in early May combined with an in-crop herbicide application increased crop establishment by 210 plants m(-2). This in turn increased aboveground crop biomass and seed yield by as much as 549 and 617 kg ha(-1), respectively. This combination of factors significantly reduced aboveground weed biomass by 50 kg ha(-1), although no single factor or combination of factors affected weed seed fecundity. By seeding competitive flax cultivars at higher rates earlier in the growing season, and by combining this with an in-crop herbicide, producers can develop sound cropping systems that provide more competitive flax crops and another profitable cropping option.