The effect of winter annual weed control with 2, 4-D Amine, and Pre-Seeding Burn-off with Glyphosate/Dicamba on subsequent canola production
Date: December 1994
Term: 3 years
Status: Completed
Researcher Dr. Ken Kirkland, Agriculture & Agri-Food Canada
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: n/a
Project Summary
Researchers at the Agriculture and Agri-Food Canada Scott Research Station conducted a three-year study from 1992 to 1994 to determine if late fall or early spring applications of 2,4-D amine had an effect on subsequent canola emergence and growth. Overall, the research results showed that producers could safely apply 2,4-D in the fall prior to seeding canola the following spring. Canola producers involved in zero tillage or direct seeding systems, and those practicing conventional tillage who wish to avoid a late fall tillage could benefit from the October application of 2,3-D for winter annual weed management.
Late fall or early spring application of 2,4-D to control winter annual weeds prior to canola had not been recommended as the herbicidal effects on canola growth and development on varying soil types were not well defined. The concern was that the amount of residual 2,4-D remaining in the soil the following May could be sufficient to injure canola seedlings.
Researchers at the Agriculture and Agri-Food Canada Scott Research Station conducted a three-year study from 1992 to 1994 to determine if late fall or early spring applications of 2,4-D amine had an effect on subsequent canola emergence and growth. They also wanted to determine if seed placement methods or soil type had an effect on canola response to 2,4-D. Other objectives focused on the effect of a 0 to 10 day time interval between spring application of 2,4-D, and the effect of potential residue from the dicamba portion of a pre-seeding burnoff treatment with Rustler on canola.
Research sites were established on Dark Brown (3.5% OM), Thin Black (5% OM) and Grey-Wooded (1% OM) soils located in west-central and northwest Saskatchewan. Applications of 2,4-D at the recommended rate of 0.34 litre/acre and twice the recommended rate of 0.68 litre/acre were made in the fall and early spring prior to planting Brassica napus (Bounty) and B. rapa (Parkland) canola from 1992 to 1994. Over the three years of the study, there was no effect on Parkland and Bounty canola plant stands or yields at any of the locations from both rates applied in mid-October. The late April application of 2,4-D at the recommended rate did not affect canola plant stand or yield at any location, however the 0.68 litre/acre rate did reduce plant stands of both canola types on the Dark Brown soils.
Researchers also looked at the effect of applying 2,4-D amine at 0.45 litre/acre at 10, 7, 3 and 0 days prior to seeding Parkland and Bounty canola. The results indicated that 2,4-D applied within 10 days of canola planting will cause significant stand and yield reductions in lower organic soils. However, on higher organic matter (Black) soils the risk is greatly reduced.
In the trials comparing seed placement using a narrow opener hoe-drill and a double-disc press drill into soil that had been treated with 0.34 or 0.68 litres/acre of 2,4-D amine a few days prior to seeding, the results showed that overall there was no differential reaction to 2,4-D residue from either method of seed placement. Researchers also tested the effect of Rustler applied as a pre-seeding burnoff prior to seeding canola, and over the two years of this study at three locations the results showed no adverse effects on canola yield.
Overall, the research results showed that producers could safely apply 2,4-D in the fall prior to seeding canola the following spring. In soils with organic matter contents ranging from 2.0 to 6%, the fall application of 2,4-D at either the recommended rate or twice the recommended rate did no damage to the succeeding canola crop. The same rates applied in the spring did injure canola on the Dark Brown soil, and application at this time of year would involve risk on this soil type. This risk in the Dark Brown soil zone would be greatly diminished in years when the separation between application and seeding date were greater, and May precipitation was normal or above.
Canola producers involved in zero tillage or direct seeding systems, and those practicing conventional tillage who wish to avoid a late fall tillage could benefit from the October application of 2,3-D for winter annual weed management.
Scientific Publications
Kirkland, K. J. 1997. Implications of late fall and early spring 2,4-D applications on subsequent canola production on Black, Dark Brown and Gray Wooded soil. Can. J. Plant Sci. 77: 699-702.