Evaluation of New Herbicide Options for the Control of Foxtail Barley (Hordeum jubatum) in Spring Wheat

• Author / Creator

  Vercaigne, Mathew

• Foxtail barley (Hordeum jubatum) is a perennial grass increasing in prevalence in western Canadian cereal fields. Seedling, over-wintering-juvenile and mature stages makes herbicide timing and selection challenging for producers. Field experiments were conducted at six sites over two years to characterize the response of established seedling and mature foxtail barley populations to combinations of short residual herbicides applied PRE and POST seeding with glyphosate. Experiment one evaluated PRE short residual herbicides: Propoxycarbazone-sodium (2), flucarbazone-sodium/tribenuron and pyroxasulfone at rates of 7.5, 10, 21.79 and 150 g ai ha-1 respectively, tank-mixed with glyphosate at 450 and 900 g ae ha-1. Experiment two evaluated combinations of propoxycarbazone, flucarbazone/tribenuron and pyroxasulfone with the high rate of glyphosate followed by a POST application of thiencarbazone-methyl at 4.94 g ai ha-1. Foxtail barley seedling and mature populations varied among sites, Scott having the highest mature population at 76 mature plants m-2, while St. Albert had the highest seedling population at 81 seedlings m-2. Visual control, seedling emergence density, foxtail barley biomass, wheat biomass and wheat seed yield were quantified. Herbicides applied pre-seeding in the absence of glyphosate failed to control mature foxtail barley. However, propoxycarbazone at 10 g ai ha-1, flucarbazone/tribenuron and pyroxasulfone applied in combination with the high rate of glyphosate increased control to 73.9%, 72.1% and 74.4% at Lethbridge 2016, Olds and Scott, respectively. Moreover, at Lethbridge 2015, Vermilion and St. Albert control increased to 90.4%, 90.8% and 89.3%, respectively. Pyroxasulfone tank-mixed with the high and low rate of glyphosate reduced foxtail barley seedling emergence compared to rates of glyphosate applied alone (29 to 4 seedlings m-2). Glyphosate at both rates applied with and without residual herbicides reduced foxtail barley biomass compared to the non-treated check. However, the high rate of glyphosate did not significantly reduce foxtail barley biomass more than the low rate (49.91 to 27.45 g m-2). The addition of residual herbicides to the high rate of glyphosate did not increase wheat biomass or seed yield. Tank-mixing propoxycarbazone at 10 g ai ha-1 with the high rate of glyphosate followed by thiencarbazone reduced foxtail barely biomass compared to the high rate of glyphosate applied alone (28.67 to 4.53 g m-2). Seedling emergence was observed over an extended period in spring and post-harvest, suggesting that both pre-seeding and post-emergent control timings along with a multi-year strategy may be required to reduce future foxtail barley populations. This research indicates that by adding a short-residual soil applied herbicide to glyphosate at a pre-seeding timing, followed by a post-emergent herbicide application, producers can control foxtail barley for the growing season in spring wheat.

• Subjects / Keywords

  • Pyroxasulfone
  • Propoxycarbazone-sodium
  • Glyphosate
  • Foxtail barley
  • Herbicide
  • Hordeum jubatum
  • Seedling recruitment

• Graduation date

  Fall 2017

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3571824B

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.