Weed & Pest
Austrian fieldcrest poses threat as new invasive species in WyomingWritten by Saige Albert
In mid-June Mark Daluge, Wyoming Weed and Pest Landowner Program Coordinator, found an infestation of Austrian fieldcress in Teton County – the first detection of the species in the county and third in the state. Austrian fieldcress has also been found in Sublette and Park counties.
“While we can’t be completely confident how Austrian fieldcress became introduced, we speculate that it was likely brought either in material used to construct a berm or potentially contaminated equipment,” said Wyoming Weed and Pest in a news release. “It appears to be spreading both by seed and aggressive lateral root creep.”
Since locating the primary infestation, Wyoming Weed and Pest has reported one other satellite infestation along a county road that sees relatively high traffic.
In Sublette County, Austrian fieldcress was located in 2008 in a hay field near Pinedale by a Weed and Pest employee.
“Similar to Sublette County, Park County found Austrian fieldcress in a field that had a center pivot system,” Wyoming Weed and Pest Coordinator Slade Franklin says. “Sublette County’s case was found in an irrigation ditch.”
Austrian fieldcress is likely to be found in areas where there is water at least six months out of the year. Sublette County reported that the plant grew “out of the water” from the irrigation ditch it was found in.
“Austrian fieldcress is a very competitive and persistent perennial that typically grows in wet soil,” says Wyoming Weed and Pest.
The invasive primarily spreads through its creeping root system, though it can also be introduced by seed and detached root fragments.
“If fieldcress is present, it will likely be more than just one or two plants,” Franklin comments. “It will more likely be a big patch of yellow flowers before people start to notice it.”
When looking at the plant, flowers form in loose clusters at the tip of branches. Each flower has four small, yellow petals.
Alternate leaves are distributed down the stem, and the plant can grow up to three feet tall.
“There are a lot of yellow flowered plants in Wyoming, so if people see something they aren’t used to, take a sample to the Weed and Pest so we can identify it.”
Austrian fieldcress will outcompete native grasses and other vegetation.
“With the university, Sublette County worked to determine treatments,” Franklin comments. “It is a very hard plant to treat, and there are experiments with various herbicides that are ongoing.”
Franklin also notes that Sublette County has seen success in treating Austrian fieldcress through application of Plateau, an herbicide with the active ingredient imazapic.
“It is also a perennial, so we can’t just mow it off to deal with the problem,” he adds.
“We need to be vigilant in looking for Austrian fieldcress,” Franklin comments. “We have a lot to figure out on treating this plant, but we are working hard to find good treatments.”
Because invasive species threaten natives across the range, Wyoming Weed and Pest recommends taking several steps to help prevent their spread.
First, drain, clean and dry all gear and boats to avoid transferring plant seeds or residue between locations. Also, burn local or certified firewood and use weed-free hay.
Staying on trails when outdoors can also reduce the chance that plant materials may be transferred.
After visiting an area, make sure to remove mud and seeds from boots, gear and equipment, including vehicles.