Tillage, Fertilizer and Herbicide Effects on Weeds in Canola

Date: December 1994
Term: 4 years
Status: Completed
Researcher: Dr. Lawrence Townley-Smith, Agriculture and Agri-Food Canada
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: n/a

Project Summary

Researchers at the Melfort Research Station initiated a four-year project in the fall of 1991 to identify which combination of tillage, fertilizer and herbicide applications would provide acceptable control of cruciferous weeds and maintain high canola yields on cereal stubble. Overall, the study showed that fertilizer application method had little consistent effect on canola growth, development or yield, and showed little influence on weed populations. In drier years, reduced tillage systems yielded the highest, but this was not the case in wetter years.

Researchers at the Melfort Research Station initiated a four-year project in the fall of 1991 to identify which combination of tillage, fertilizer and herbicide applications would provide acceptable control of cruciferous weeds and maintain high canola yields on cereal stubble. The seedbed preparation systems included: a) conventional, fall tillage to incorporate trifluralin with tillage in the spring for weed control; b) reduced, fall tillage to incorporate trifluralin with chemical weed control in the spring; and c) direct seeding, no fall or spring tillage with chemical weed control in both fall and spring.

Glyphosate was used to replace tillage for fall and spring weed control. Both Argentine and Polish canolas were grown with and without Muster within each seedbed preparation system from 1992 to 1994. A delayed seeding treatment using Polish canola with a glyphosate treatment before emergence was also included. All tillage operations were performed with a field cultivator and seeding was done with a hoe press drill. A hoe press drill was also used to apply fertilizer by fall banding, fall broadcasting and spring broadcasting for each of the seedbed/herbicide systems.

Overall, the study showed that fertilizer application method had little consistent effect on canola growth, development or yield, and showed little influence on weed populations. Moisture conditions influenced yields and seeding systems. In 1993, which was a relatively dry year, reduced tillage, particularly avoiding spring tillage, increased canola leaf area, crop development and improved seed yield. However, the reverse was true in 1994, which was a wetter year.

Overall, the use of trifluralin and tillage compared to glyphosate without tillage, showed a reduction in cleavers, wild oat, wild buckwheat and lamb’s quarters. However, stinkweed and wild mustard populations were substantially reduced with glyphosate.

As expected, Polish canola developed faster and had higher growth than Argentine under all management combinations for normal seeding dates. Delayed seeding usually produced a crop that was smaller, later and in most cases had lower yield. However, delayed seeding also tended to reduce early season weed populations, and may be a viable strategy for organic or very low input production systems.

Full Report PDF: Tillage, Fertilizer and Herbicide Effects on Weeds in Canola