It first got its name from the way it cheated farmers out of their grain crops, but cheatgrass has long since become a forage-stealing scoundrel on rangelands and pastures.
Found in all 50 states, most Canadian provinces and parts of Mexico, estimates of Western U.S. infestations alone range from 56-100 million acres. When it gains a foothold, cheatgrass not only steals forage potential, but it's a significant concern as a fire hazard as it quickly changes into a blonde haze of fast-burning fuel.
Cheatgrass, also known as downy brome (Bromus tectorum), and its equally obnoxious cousin Japanese brome (Bromus japonicus) are annuals that usually germinate in the fall and overwinter as seedlings. Continuing their growth in the early spring, they readily invade tame pastures and native rangelands, forest openings, filter strips and riparian areas.
“These two species probably cause more irritation to grazing managers than any other undesirable species out there,” says Eric Mousel, South Dakota State University range management specialist. “They're especially difficult to manage because they shoot out of the ground before most other plants, soak up the lion's share of the moisture and nutrients, and then set seed, becoming fully mature within a couple of weeks.”
A three-tactic strategy
“Grazing, combined with multiple herbicide treatments and prescribed burning, will likely be required over a period of years,” Mousel says. “There are several options we can use to take advantage of the growth habit of these weed species and limit the damage they do to our forage resource.”
But, you have to get to cheatgrass early.
“Graze it before it burns up,” advises Charlie Rose, Winnemucca, NV. “At spring turnout, cheatgrass is about the only thing green around here.” He says in the early stage of growth — usually early April in northern Nevada — it's an excellent feed. “We've tested it to be around 18% protein.”
Rose says cows can get fat on cheatgrass and breed up exceptionally well. But once the moisture is gone from the top 2-3 in. of soil, cheatgrass starts to head out. “Then it can go from a high-quality forage to 3-5% protein in a just few days,” Rose says.
The problem with grazing cheatgrass in northern Nevada, he says, is it's almost always found on public land, and federal-land managers won't let producers turn out the number of cattle needed to effectively control cheatgrass growth.
In addition, range fires over the past decade have added to cheatgrass spread in Nevada. There, the Wildfire Support Group is working with local ranchers to study and apply cheatgrass control strategies on their lands.
“They've found some success, but there seems to be a lack of plant materials available that can be used to effectively rehabilitate cheatgrass-invaded sites with species that provide similar or better forage-production capabilities,” says Ryan Shane, Nevada Department of Forestry resource manager.
“It's amazing to see the diversity of opinions here in Nevada on cheatgrass,” adds Shane. “But cheatgrass is generally the enemy of land-management agencies because it represents the destruction and removal of intact, native ecosystems.”
At the Padlock Ranch, which straddles northern Wyoming and southern Montana, managers use several methods to control, or at least limit, the spread of annual bromes following several bouts with wildfire. The main tool is timed grazing, which allows perennial plants to regain their presence in areas where cheatgrass has dominated.
“We try and schedule early grazing on areas that have large cheatgrass populations. Cattle are then moved off quickly to allow the native grasses to mature,” says Don Luse, Padlock's natural resource manager. “This helps to control cheatgrass by utilizing the plant prior to seed set and allowing native plants to compete for space.”
Luse notes that through careful grazing management, they've restored native perennial plant populations to levels better than when pastures heavily infested with cheatgrass were purchased 25 years ago.
“When plants are growing fast, move fast,” he says about his grazing philosophy. “Moving through pastures rapidly in the spring when cattle are grazing cool-season grasses, and then coming back through the pasture later to utilize warm-season grasses allows the native perennials to reestablish.”
Grazing to control cheatgrass requires more pressure than a normal summer-stocking rate can provide, Mousel agrees. “Mob grazing can provide the increase in grazing pressure needed to successfully control these weeds.”
He adds that cool-season grasses generally won't start growing until later. So as long as you pull cattle off pasture or at least back the grazing pressure down to summer stocking rate levels, no damage will be done, he says.
“Let the mob clean up the cheatgrass in an area and keep them moving to fresh allotments,” Mousel explains. “Livestock probably won't clean up every single weed plant, but you can't beat the cost of this weed-control treatment.”
Plan herbicide treatments
Herbicide treatments to control cheatgrass also need to be carefully planned.
Because cheatgrass and Japanese brome generally green up at least two weeks before most key forage species, some unique chemical-control opportunities exist. On rangeland, use of Roundup (glyphosate), Journey (imazapic plus glyphosate), or Plateau (imazapic) provide management options for cheatgrass infestations.
While cheatgrass is a prolific seed producer, seeds usually don't remain viable in the soil for more than 2-3 years. Thus, chemical control to prevent seed production in the spring reduces the number of seeds in the soil and provides long-term benefits.
On the Padlock Ranch, in areas where cheatgrass populations are exceptionally high and grazing management isn't working, a light application of Roundup in the spring is used.
“It helps reduce the competition from the annuals without harming native perennials,” Luse explains. “The application will set the perennials back depending on the amount of herbicide used, but they will come back.” He says 4-6 oz. of Roundup/acre works well without damaging nontarget species.
Consensus is that care should be taken to only apply Roundup when range grasses are dormant to avoid risk of injury to desirable plant species. If perennial grasses have initiated new growth, Roundup at its lower recommended rate can be used, but some growth stunting of perennial grasses may occur.
Meanwhile, Journey provides pre- and postemergence control of cheatgrass, says Fabian Menalled, Montana State University weed specialist.
For best results, Journey should be applied in late summer or fall before cheatgrass seedlings emerge and prior to planting desirable species; don't use after newly seeded desirable species have begun to emerge.
“Spring applications of Journey can increase consistency in cheatgrass control,” Menalled explains. “However, these spring applications should be limited to areas without a large number of desirable plants.”
Plateau is a broad-spectrum herbicide that provides control of cheatgrass and allows desirable native grasses and forbs to reestablish after treatment. Menalled recommends late-summer or fall applications of Plateau, preemergent to germination for the most effective control of cheatgrass and other bromes.
“This invasive species, while always present, really became a problem after the drought years of the last decade,” Luse concludes. “Cheatgrass is a formidable competitor with our native grasses.”
Clint Peck is director of Beef Quality Assurance, Montana State University.