Managing invasive winter annual grasses on rangeland and in other non-crop areas remains challenging.� Currently, there are limited options for consistent control of winter annual grasses, and even fewer that provide multiple years of control and do not injure desirable plant communities.� Imazapic has been one of the most-widely used herbicides on rangeland, but this herbicide lacks consistency beyond the year of application and can cause injury to perennial grasses.� Indaziflam, a new herbicide mode of action for rangeland weed management, has provided long-term residual control of winter annual grasses.� For each herbicide, seven rates were used to develop dose-response curves for 6 species of invasive annual grasses.� Log-logistic regression was conducted to determine GR50 values.� Indaziflam provided superior winter annual grass control across all species, compared to imazapic.� The GR50 values for imazapic were on average 15 times greater than indaziflam.� Four field studies were conducted to compare downy brome and feral rye control with indaziflam to currently recommended herbicides, and evaluate treatment impacts on the established co-occurring plants.� Indaziflam treatments resulted in a 10 to 16-fold increase in perennial grass biomass 2 YAT and maintained downy brome and feral rye control (95-100%); while, imazapic resulted in 2 to 4-fold increase in perennial grass biomass 2 YAT, with no impact on downy brome and feral rye biomass.� Indaziflam treatments showed no visual injury to the non-target perennial grasses, forbs, and shrubs.� Indaziflam provided superior residual downy brome and feral rye control.� The residual downy brome control achieved by a single indaziflam application could provide the opportunity to significantly reduce downy brome abundance and allow adequate time for desirable co-occurring plants to re-establish.� This research provides evidence of a new option for invasive winter annual grass control on rangelands. Studies are underway to develop a grazing label for Indaziflam.
Oral presentation and poster titles, abstracts, and authors from the Society for Range Management (SRM) Annual Meetings and Tradeshows, from 2013 forward.