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Abstract Detail


Geddes, Charles M. [1], Gulden, Robert H. [2].

Weed management via targeted soil seedbank disturbance: Brassica napus L. in western Canada.

Brassica napus L. (canola) is the most common oilseed crop grown in western Canada and contributes $19.3 billion to the Canadian economy every year. Since the introduction of herbicide-resistant (HR) varieties in 1996, harvested canola acreage has grown from 8.5 to 19.8 million acres in Canada (2013). Volunteer canola, an agricultural weed derived mainly from canola harvest losses, has become the 14th most common weed in western Canada based on relative abundance. The seedbank of volunteer canola generally persists for three to four years, but can persist for up to ten years in certain cases. Certified seedlot contamination with unwanted HR traits, seed losses both before and during harvest, weed seed return in subsequent years, and weed management decisions have all contributed to the abundance of this agriculturally significant weed. In 2013/2014, a field study evaluating the effect of timing and intensity of soil disturbance following canola harvest was conducted at three locations in Manitoba, Canada. Seedbank densities were quantified immediately following canola harvest and in the following spring. Seedling recruitment was evaluated in the autumn and throughout the first year after canola production. Soil disturbance with a tine harrow in addition to seeding winter wheat or tillage via tandem disk immediately after canola harvest resulted in approximately three-fold greater autumn seedling recruitment compared to zero tillage. These high disturbance treatments immediately after harvest also caused the greatest reduction in viable volunteer canola seed in the seedbank the spring after canola production (approximately two-fold compared to zero tillage). The proportion of the persisting spring seedbank differed among sites and was likely influenced by soil type, which, aside from biological properties, differed in textures ranging from sandy loam to silty loam to heavy clay (18%, 1%, and 8% of the initial seedbank, respectively). These results indicate that delayed tillage systems identified for managing volunteer B. napus seedbank dynamics in Germany and the United Kingdom may not be an effective management option in the agroecological environment of western Canada. Agronomic and environmental differences as well as the effect of soil type on volunteer canola seedbank fates warrants further investigation.

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1 - University of Manitoba, Plant Science, 222 Ag Building, 66 Dafoe Road, Winnipeg, MB, R3T 2N2, Canada
2 - Univeristy of Manitoba, Plant Science, 222 Ag Building, 66 Dafoe Road, Winnipeg, MB, R3T 2N2, Canada

Volunteer canola
Timing of disturbance
Seedbank persistence
seedling recruitment.

Presentation Type: Oral Paper:Papers for Topics
Session: 62
Location: Salon 8/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 8:15 AM
Number: 62002
Abstract ID:678
Candidate for Awards:Economic Botany Section best poster

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