IMPLICATIONS OF LATE FALL AND EARLY SPRING 2,4-D APPLICATIONS ON SUBSEQUENT CANOLA PRODUCTION ON BLACK, DARK BROWN AND GRAY WOODED SOIL

Late fall or early spring application of 2,4-D to control winter annua l weeds prior to canola has not been recommended as the herbicidal eff ects on canola growth and development on varying soil types are not we ll defined. 2,4-D was applied to Black, Dark Brown and Gray Wooded soi ls located in west-central and northwest Saskatchewan. Applications we re made in the fall and early spring prior to planting Brassica napus L. and Brassica rapa L. canola from 1992 to 1994 at the recommended (0 .42 kg ha(-1)) and twice the recommended rate. The rate of 2,4-D appli ed had no effect on canola plant population, pods per plant, yield, gr een seed, chlorophyll, kernel or test weight. Application of 2,4-D in the fall had no effect on any variable while spring application reduce d plant stands and increased green content but had no effect on pod pr oduction, yield or chlorophyll content. Late fall application of 2,4-D prior to canola in relation should be recognized asa valuable additio n to weed management in canola, particularly when direct seeding is pr actised.