We can fight back by removing the invasive annual grasses that provide the fuel.

With more than 100 fires blazing throughout the western United States, tens of thousands of acres are burning every day, displacing thousands of people and engulfing entire communities into flames. More than 4.6 million acres of land has already burned in the year 2020 alone, as of mid-September.

While forest fires capture the headlines, rangeland fires are also devastating millions of acres across the west. For example, in 2018, the Martin and South Sugarloaf fires burned nearly 700,000 acres of Nevada rangeland. Since 2000, Nevada has seen more than 20 fires greater than 100,000 acres. The impacts of widespread wildfire are devastating. Forage for livestock is destroyed, wildlife habitat is degraded and communities are disrupted.

Firestarter: What Sets them Ablaze

In a healthy rangeland system, wildfires are infrequent, with a cycle that can be 100 years or more. Now, wildfires can be as frequent as every five to 10 years. The culprit? Invasive winter annual grasses that occupy millions of acres across the west. The most widespread is cheatgrass but others such as medusahead and ventenata are even more devastating. The invasive annual grasses provide the fuel to ignite and carry wildfire. The wildfire in turn results in more annual grass invasion.

“It's becoming a critical issue throughout the west because now we have an arrangement of species that can replace our native grasses and our native forbes, and affect things that grow above them like the shrubs and the trees and bushes,” said Gloria Edwards, director of the Southern Rockies Fire Science Network.

The problem is growing faster than current management practices are able to slow this trend. These invasive grasses germinate in the fall or winter, grow rapidly in late winter and early spring, then turn brown and die in late spring into summer at the exact same time that the fire risk increases. Every year, the invasive grasses add fine fuel to the thatch layer and seed to the soil seed bank.

“The thatch layer created by invasive annual grasses results in a continuous carpet of fine fuel, which puts people and communities at risk and perpetuates the cycle of ecosystem degradation,” said Harry Quicke, stewardship and development manager, Envu Western Region. “One strike of lightening, a downed powerline or a fallen cigarette and the entire range is aflame. It burns rapidly, depletes native species and causes a tragic loss to ranchers, the broader rangeland community and to wildlife.”

“If we have ways of understanding and managing these weeds, and we can interrupt these fire cycles that come along with these invasive species, then we can step further in managing wildfire,” said Edwards. “Many of these species bring a much different relationship with fire than our native plants.”

Rejuvra Herbicide for Invasive Annual Grass Control

There is hope. Rejuvra^® herbicide is a pre-emergence herbicide recently labeled for use in rangeland. It has been intensively researched with over 130 trials across the western United States. Importantly, Rejuvra is a selective herbicide. This means that perennial plants are left in place and respond quickly to the additional water and nutrients that become available when the invasive annuals are controlled.

An excellent choice for invasive annual grass control, Rejuvra helps to reduce the fine fuel loading by controlling species contributing to this problem. This in turn reduces wildfire hazard. With just one application needed for up to four years of control, Rejuvra manages the soil seed bank, leaving remnant desirable perennial populations to recolonize while helping to restore plant diversity and promote beneficial wildlife habitat.

“With Rejuvra herbicide, we can deplete the invasive annual grass seedbank, reduce wildfire risk and give desirable perennial grasses, forbs and shrubs the opportunity to grow,” said Quicke.

“That's [Rejuvra is] one tool in our toolbox,” said Edwards. “We need a lot of tools within our toolbox because this is an urgent situation to manage our habitats. So, we need to understand the science of prescribed fire, and the application and science of herbicides, and livestock control, and mechanical means.”

Increasing Wildfire Frequency in Rangeland

While wildfire is natural in rangeland, the fine fuel provided by invasive annual grasses results in a far greater frequency of fires.

Many native plant and animal species are not adapted to this shortened fire cycle. For example, shrubs, such as sagebrush, take many years to re-establish after a fire. With a shortened fire cycle, these species do not have time to recover between fires and end up being eliminated.

“Our native plants would've been burning on more infrequent fire cycles every 3-30 years,” said Edwards. “And now, we have a sweep of invasive species that is burning with greater intensity and greater frequency, such that they reseed themselves and adapt to this frequent fire environment, like we're seeing in California. Like we see in Nevada. Like we're seeing in a lot of western states.”

Fortunately, Rejuvra herbicide provides multiple years of invasive annual grass control. Alongside cultural and mechanical practices, Rejuvra provides an opportunity to manage the soil seed bank of invasive grasses, helping to bring back desirable vegetation and mitigate wildfire risk.

Rejuvra Herbicide Key Product Benefits

• Consistent, long-term weed control: Multi-year control of invasive annual grasses with seed bank depletion.
• Releases and restores perennial native vegetation: Perennial plants respond quickly to the additional water and nutrients that become available when invasive annual grasses are controlled, resulting in increased perennial biomass and forage production, and restored native plant communities.
• Improved wildlife habitat: Removes invasive winter annuals, resulting in recolonization of grass, forbs and shrubs beneficial to pollinators, birds, and other wildlife.
• Reduced wildfire risk: Decreases fine fuels associated with wildfires.
• Economical solution: Fewer applications are needed to control weeds, saving time and labor. Multi-year weed control with a single application can provide a greater return on investment (ROI).
• No grazing restrictions: For application rates of five ounces per acre.
• Standard PPE requirement: Long-sleeved shirt, long pants, shoes plus socks and chemical-resistant gloves. Follow state requirements if more stringent.