Downy brome is an annual winter grass that has invaded millions of acres of western rangelands and wildlands. It can outcompete native vegetation and can increase the frequency and severity of wildfires by leaving behind dense mats of litter at the end of its growing season.

In a multiyear study featured in the journal Invasive Plant Science and Management, scientists explored the benefits of pairing prescribed burning with applications of the residual herbicide indaziflam – a proven tool for restoring sites that have been degraded by invasive winter annual grasses.   

The team applied the herbicide to burned and unburned sites to evaluate the impact on both downy brome control and native plant communities. They found that the combination of burning and indaziflam produced better and longer-term results than either method used alone. Together the two techniques improved downy brome control and plant community diversity at one study site. In addition, lower application rates were possible since more of the herbicide reached the soil to control germinating seeds across multiple seasons.

Other key findings: Combining the burning-indaziflam regimen with selective, postemergence herbicides can help land managers extend the application window. Combining indaziflam with imazapic or rimsulfuron provides a wider application window than combining indaziflam with glyphosate. In addition, applying a selective, post-emergence herbicide with higher rates of indaziflam is an option for controlling downy brome in arid sites where litter has not been burned.

Want to learn more? You can read the article “Prescribed burning followed by indaziflam enhances downy brome (Bromus tectorum) control” freely available for one month.