Student management

MSU graduate student works to understand and control invasive weed on Crow Reservation

Over the past decade, Ventenata dubia, an invasive grass, has appeared in 24 counties in Montana, where it has reduced plant diversity and reduced forage availability for livestock and wildlife.

As weeds began to take over the grounds of his home on the Crow reservation, Zach Fighter, a graduate student in Montana State University’s Department of Land Resources and Environmental Sciences in the College of Agriculture, saw a subject for his grassroots project. search for mastery.

“It’s starting to get serious, and I don’t think a lot of people knew it was there because they didn’t even know what weed was,” said Fighter, a Pryor native and registered member of the tribe. “It could potentially take over and invade your pasture and take away your desirable species, what your cattle want to eat, and by moving that you’re not getting good forage value and losing money.”



Zach Fighter, far left, works alongside co-advisors Jane Mangold, middle left, and Scott Powell, middle right, on the Crow reservation, exploring ways to address invasive grass ventenata through chemical control and remote sensing. Photo courtesy of Zach Fighter.

Fighter works alongside co-advisers Jane Mangold and Scott Powell on the Crow reservation, exploring ways to address ventenata through chemical control and remote sensing.

Fighter’s research is supported by a grant from the Montana Noxious Weed Trust Fund. The research team is collaborating with others from the Bureau of Indian Affairs, Big Horn County and the University of Montana. Fighter is also part of the Sloan Indigenous Graduate Partnership, a scholarship program that supports graduate Indigenous students pursuing studies in science, technology, engineering, or mathematics with the goal of increasing the number of Native Americans earning master’s and doctoral degrees. in STEM disciplines.



As part of their research on chemical controls of ventenata, the team uses two different herbicides, indaziflam and imazapic. The first is applied before ventenata germination, while the second is applied after germination. Fighter applied indaziflam in August 2021 and imazapic in November 2021 and will evaluate the results this summer to see how well those treatments controlled the weed. In addition to herbicides, Fighter is studying a soil amendment that could control weed by adding micronutrients that encourage the growth of desirable species.

Fighter has four research sites, two near Pryor, one near Lodge Grass, and another east of Crow Agency. Each 10-by-60-foot patch of land is divided so that each treatment has its own area, giving Fighter a better understanding of which controls are working at which rates.

The method of application is just as important as understanding which herbicide is most effective. Fighter uses high and low water transport rates. High rates mimic ground application and low rates mimic aerial application. Ground applications involve the use of ATVs or walking on property and use 15 gallons of water per acre. Aerial applications, however, use only 5 gallons per acre and can be administered by helicopter or airplane, making it easier to cover larger tracts of land like those found on the Crow reservation.

“The Crow Preserve is one of the ventenata hotspots in the state,” said Mangold, an invasive plant specialist for MSU Extension and a professor at LRES. She has been researching the herb since 2015, but this is the first time she has researched its presence on the reserve. “In other places, I have seen ventenata growing in small, isolated patches. But the ventenata I’ve seen on the reservation and in Wyoming is more ubiquitous in the landscape.

Ventenata is an annual winter grass with an open, airy inflorescence. The stems have a stiff, threadlike texture. Its leaves are curled lengthwise or folded, and its roots are shallow, about 1 to 2 inches deep.

To measure the effectiveness of chemical controls, Fighter will use various remote sensing tools to collect data on plant health and vigor. Powell, a professor at LRES, specializes in remote sensing and spatial analysis to measure vegetation. He said the data they will collect is based on the amount of light reflected from plants, including visible and non-visible light, such as near infrared.

“The difference between a healthy plant and an unhealthy plant in the near-infrared spectrum is really pronounced,” Powell said. “You can develop indices like a remote sensing vegetative index, which allows you to track the health of the plant after it’s been sprayed with herbicides.”

Both Mangold and Powell said Fighter absorbs as much information as possible and is good at discussing tough topics with voters.

“We met with the Big Horn County Weed District, and Zach led the whole conversation. Scott and I were there, but it was more about Zach and you see him interacting with people and he’s really good at it,” Mangold said. “He collects information and has a way of processing it and putting it into practice. You can mostly see him when interacting with local community members on the reserve.

Fighter earned his bachelor’s degree in rangeland ecology and management from MSU in 2017. He said he’s always been interested in invasive species, and when he decided to further his education, it made sense for him to specialize and to enter the LRES program to develop their knowledge of the courses.

Fighter plans to graduate in December 2022 and hopes to continue her career in invasive species, ideally with the Bureau of Indian Affairs office in Billings.

“It’s good to know that I can potentially help managers and landowners and provide new information about this species,” Fighter said. “I’m interested in seeing how my controls work and if they work well this summer I can provide managers and owners with vital information to start using them on their land immediately.”