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Minimizing competition between glyphosate-resistant volunteer canola (Brassica napus) and glyphosate-resistant soybean: impact of soybean planting date and rate

Published online by Cambridge University Press:  07 October 2019

Allyson Mierau
Affiliation:
Graduate Student, Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
Eric N. Johnson
Affiliation:
Research Assistant, Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
Robert H. Gulden
Affiliation:
Associate Professor, Department of Plant Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
Jessica D. Weber
Affiliation:
General Manager, Western Applied Research Corporation, Scott, Saskatchewan, Canada
William E. May
Affiliation:
Crop Management Agronomist, Agriculture and Agri-food Canada, Indian Head, Saskatchewan, Canada
Christian J. Willenborg*
Affiliation:
Associate Professor, Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
*
Author for correspondence: Christian J. Willenborg, Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, 51 Campus Drive, Saskatoon, Saskatchewan, Canada S7N 5A8. Email: chris.willenborg@usask.ca

Abstract

In recent years, soybean acreage has increased significantly in western Canada. One of the challenges associated with growing soybean in western Canada is the control of volunteer glyphosate-resistant (GR) canola, because most soybean cultivars are also glyphosate resistant. The objective of this research was to determine the impact of soybean seeding rate and planting date on competition with volunteer canola. We also attempted to determine how high seeding rate could be raised while still being economically feasible for producers. Soybean was seeded at five different seeding rates (targeted 10, 20, 40, 80, and 160 plants m−2) and three planting dates (targeted mid-May, late May, and early June) at four sites across western Canada in 2014 and 2015. Soybean yield consistently increased with higher seeding rates, whereas volunteer canola biomass decreased. Planting date generally produced variable results across site-years. An economic analysis determined that the optimal rate was 40 to 60 plants m−2, depending on market price, and the optimal planting date range was from May 20 to June 1.

Information

Type
Research Article
Copyright
© Weed Science Society of America, 2019

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