Implications of late fall and early spring 2,4-D applications on subsequent canola production on Black, Dark Brown and Gray Wooded Soil

Abstract

Late fall or early spring application of 2,4-D to control winter annual weeds prior to canola has not been recommended as the herbicidal effects on canola growth and development on varying soil types are not well defined. 2,4-D was applied to Black, Dark Brown and Gray Wooded soils located in west-central and northwest Saskatchewan. Applications were 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 applied had no effect on canola plant population, pods per plant, yield, green seed, chlorophyll, kernel or test weight. Application of 2,4-D in the fall had no effect on any variable while spring application reduced plant stands and increased green content but had no effect on pod production, yield or chlorophyll content. Late fall application of 2,4-D prior to canola in rotation should be recognized as a valuable addition to weed management in canola, particularly when direct seeding is practised. Key words: Canola, 2,4-D, soil residual, injury