Tekiela: Targeted grazing addresses weed challenges on Wyoming rangelands
The majority of Wyoming ranchers likely have pressure from weed species on their ranching operations.
“More than half of folks typically have a weed issue,” comments Dan Tekiela, University of Wyoming Extension weed specialist, who noted targeted grazing can provide a potential solution to alleviate the challenges posed by weed species.
Tekiela says, “Targeted grazing is the use of grazing by a specific kind of livestock with specific timing, frequency, duration and intensity to accomplish defined goals in vegetation management.”
Whether it be sheep, cattle, goats or any other livestock species, Tekiela says the focus of targeted grazing should be on plant species and vegetation management first.
“The goal is trying to reduce cover or biomass of one or more weed species while increasing cover or biomass of one or more desireable plant species,” he comments, emphasizing reduction and not elimination of a species is the desired outcome.
Elimination through targeted grazing is unrealistic, he noted, adding targeted grazing does not focus on just one species but rather the system as a whole.
“We’re targeting one species while also trying to increase the biomass of others. We want to make sure we’re benefitting desireable vegetation as we target non-desireable plants,” Tekiela explains. “Looking at the weed we are dealing with dictates whether we might utilize targeted grazing or not.”
As an example, Tekiela cites the widely known invasive cheatgrass, as well as two species that are relatively new to Wyoming – ventenata and medusahead.
“Ventenata and medusahead are worse than cheatgrass,” he explains. “We found a small population of both species in Wyoming two or three years ago.”
Tekiela continues, “In the case of ventenata and medusahead, we would not want to use targeted grazing because it doesn’t lead to eradication. With small populations, we should aim for eradication. Targeted grazing becomes the answer to weed problems across several hundred acres of weeds.”
A recent study from Kettering looked at practices used to manage weedy and invasive species, finding that 60 percent of research focuses on herbicides.
“When people think about weeds, they think about herbicides,” Tekiela says. “They also think of cutting, burning or hand-pulling. Grazing is only used in eight percent of situations. The only things less common than grazing are tilling, scraping, water manipulation and litter removal.”
At the same time, Tekiela continues, “We also don’t have formulas that say if we have species X on our property, here is the formula for solving the problem. Instead, we offer how to identify best management practices and utilize targeted grazing for particular species.”
While weed species may pose a challenge, Tekiela says they actually often provide decent forage quality for livestock grazing.
“Leafy spurge is often compared to high-quality alfalfa in terms of nutrition for crude protein,” he comments. “We often find that livestock avoid weedy species because of secondary compounds.”
In leafy spurge, for example, a milky sap is produced as a secondary defensive chemical that the plant produces to make it toxic or bitter.
“Leafy spurge becomes toxic to cattle, but it is not toxic to sheep. However, the milky sap makes the plant unpalatable, so they try to avoid eating it,” Tekiela explains. “If we can get livestock to eat these plants, however, it’s decent forage.”
Palatability also generally goes down as the plant grows.
“When the plants start greening up, they start creating post-secondary compounds, but the vegetation is soft and supple,” he says. “By the bolting and flowering stage, they’re not particularly palatable.”
As the plants continue to grow, they become even less palatable as nutrients go back into the roots.
“If we graze during green-up, it might seem like we can hammer the plant. But if we start grazing then, the plants can still come back. They haven’t put a lot of resources into above ground biomass,” Tekiela explains. “We’re not really taking a lot from the plant. If we do the same thing right before bolting and flowering, the plant is putting its energy into the above-ground biomass.”
If plants are targeted before they go to seed, that plant doesn’t have a chance to regrow or create seed for the season.
“If we start grazing after it creates seed, the plant is already pulling resources back into the roots, so what is the point?” Tekiela asks. “We’re trying to find the window where plants are palatable and also susceptible to grazing.”
Tekiela spoke during the 2018 West Central States Wool Growers Convention, held Nov. 8-10 in Casper.
Saige Albert is managing editor of the Wyoming Livestock Roundup. Send comments on this article to firstname.lastname@example.org.