Vegetation Response to Indaziflam and Implications for Northern Bobwhite Habitat Management

Cheatgrass ( Bromus tectorum ) is an exotic, invasive, annual grass that rapidly invades and dominates areas in North America and reduces abundance, survival, and diversity of native plants and animals. A variety of methods have been used to control cheatgrass, but herbicides seem to consistently produce the best results. Indaziflam is a pre-emergent herbicide that prevents germination and is especially effective on annual grasses. We used a randomized block design to evaluate the effectiveness of indaziflam to reduce cheatgrass cover in two vegetation communities in northeastern Colorado, and assessed the vegetation response to treatments with special focus on habitat for northern bobwhite ( Colinus virginianus ), a species of conservation concern in Colorado and throughout their distribution. In the sandsage rangelands vegetation community during June sampling, indaziflam reduced cheatgrass cover from an average of 61% cover (range, 53–70%) to an average of 5% cover (range, 4–6%). In the river bottom vegetation community during June sampling, indaziflam reduced cheatgrass cover from an average of 13% cover (range, 10–18% cover) to an average of 5% cover (range, 1–9%). With the reduction in cheatgrass cover, we documented increases in forb, bunchgrass, and bare ground cover in certain seasons and vegetation communities, which are important components of northern bobwhite habitat. We found a negative response of forbs up to 1 yr posttreatment, but by 2 yr posttreatment, forb cover was greater than in untreated control plots. Overall, indaziflam treatments tended to result in better bobwhite habitat but this benefit was not apparent in all seasons and habitat types.