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Suitability of Wild Oat (Avena fatua), False Cleavers (Galium spurium), and Volunteer Canola (Brassica napus) for Harvest Weed Seed Control in Western Canada

Tidemann, Breanne D., Hall, Linda M., Harker, K. Neil, Beckie, Hugh J., Johnson, Eric N., Stevenson, F. Craig
Weed science 2017 v.65 no.6 pp. 769-777
Avena fatua, Brassica napus, Galium spurium, Triticum aestivum, Vicia faba, canola, environmental factors, faba beans, harvesters, herbicide resistance, oats, seeds, weed control, wheat, Canada
As chemical management options for weeds become increasingly limited due to selection for herbicide resistance, investigation of additional nonchemical tools becomes necessary. Harvest weed seed control (HWSC) is a methodology of weed management that targets and destroys weed seeds that are otherwise dispersed by harvesters following threshing. It is not known whether problem weeds in western Canada retain their seeds in sufficient quantities until harvest at a height suitable for collection. A study was conducted at three sites over 2 yr to determine whether retention and height criteria were met by wild oat, false cleavers, and volunteer canola. Wild oat consistently shed seeds early, but seed retention was variable, averaging 56% at the time of wheat swathing, with continued losses until direct harvest of wheat and fababean. The majority of retained seeds were >45 cm above ground level, suitable for collection. Cleavers seed retention was highly variable by site-year, but generally greater than wild oat. The majority of seed was retained >15 cm above ground level and would be considered collectable. Canola seed typically had >95% retention, with the majority of seed retained >15 cm above ground level. The suitability ranking of the species for management with HWSC was canola > cleavers > wild oat. Efficacy of HWSC systems in western Canada will depend on the target species and site- and year-specific environmental conditions. Nomenclature: False cleavers, Galium spurium L. GALSP; volunteer canola, Brassica napus L. BRSNN; wild oat, Avena fatua L. AVEFA; fababean, Vicia faba L.; wheat, Triticum aestivum L.