Short-term Effects of Indaziflam on Non-native Brome Grass (Bromus spp.), Biological Soil Crusts, and the Endangered Dwarf Bear Poppy (Arctomecon humilis)

Abstract

Controlling invasive annual grasses is one of the top conservation priorities in the American West. Brome (Bromus spp.) has more recently invaded areas of White Dome Nature Preserve, a conservancy for endemic and endangered or threatened plants in Washington County, Utah, United States, where the use of herbicides could be effective in managing invasion. Ideal habitat for these plants is on gypsiferous soils that are largely associated with biological soil crusts. Intact biological soil crusts are important in a biological communities' ability to resist invasion by annual grasses and are critical for nutrient cycling. However, there is a lack of research on how herbicides affect biological soil crusts and specific rare plant species that are of high conservation priority. We found that indaziflam (Rejuvra, Bayer CropScience, Monheim am Rhein, Germany), applied as a preemergent, was effective at reducing brome density the first growing season after application. Indaziflam also did not initially injure the biological soil crusts. Indaziflam is reported to have multiyear effects of reducing annual grasses, which makes indaziflam a promising herbicide for conservation purposes in areas where the invasive species seed bank needs to be depleted with as little disturbance to biocrusts as possible.