Worrisome Palmer Amaranth Weed Found In Hill County

Palmer amaranth, a weed agricultural interests are desperately trying to prevent becoming established in Montana, was found last month near a grain silo in Hill County.

Agricultural groups, including those working at Montana State University Extension, have been closely tracking the weed, which is notably resistant to herbicides. There have been four reported confirmed instances of Palmer amaranth in Montana, though researchers say there isn’t a known established distribution in the state. The site is being monitored by the MSU Extension office.

The weed, while native to North America, doesn’t have a foothold in Montana. It spreads quickly and can choke out crops — it can decrease crop yields by 80 to 90 percent if left unchecked, according to a report in the New York Times. If it becomes established, the potential economic impact could be severe, according to MSU Extension’s agricultural department.

Herbicide resistant weeds are a “huge” issue in Montana, said Tim Seipel, a Cropland Weed Specialist with MSU Extension. Palmer amaranth is a pigweed with long, thin flower heads when compared to its more common relatives, such as redroot pigweed.

“If it really spreads out in crop fields in Montana, especially in our pulse crop industry and pulse fields — so lentils, chickpeas, beets — it would cost us millions of dollars, probably in additional herbicide input costs,” Seipel said. “So that’s why we’re trying to really be on top of it and keep it contained.”

One peer-reviewed study published in Frontiers in Plant Science found Palmer amaranth resistant to six different herbicide brands. The plant has found ways to adapt to human-created herbicides and is essentially outpacing science. It’s hard to kill — plants pulled out of the ground have been known to reestablish themselves and the plant itself can grow three inches in a day.

“When you have a species like Palmer Amaranth that has evolved resistance to many of our known herbicide modes of action, the way the herbicide kills the plant, what it does to the plant, you begin to have to stack modes of action on top of each other,” Seipel said. “You have to choose modes of action that may be still under patent. There’s no generic, you’re buying more complex tank mixes.”

What this means for farmers, Seipel said, is higher costs for weed control and lower prices for their products. Crops harvested in fields containing many green weeds also are stained by them, which means lower prices when farmers sell.

“You take it to the elevator and you sell it, you get docked economically for stained lentils,” Seipel said. “So you don’t get paid.”

Precipitation this summer, described as “abundant” in a press release discussing the weed, could be to blame for the plant taking root. Sepiel said the Palmer amaranth was found in a field following harvesting from what’s called a “custom cutter” or a company that follows ripening wheat through multiple states, harvesting it for producers.

Palmer amaranth is native to the American southwest and began seriously competing with cotton in the 1990s. It’s since moved to the Midwest and Mid-south.

The weed is not the only troublesome one in Montana. The MSU Extension Office also lists Kochia scoparia, a broadleaf weed, as a major threat to Montana as well because of how difficult to control it is.

These weeds can move via harvesters, trains – even birdseed, Seipel said. Recently, Palmer amaranth was found in Spokane County (Washington). It was tracked back to contaminated birdseed bought at a Safeway.

The first recorded palmer amaranth sighting in Montana? Also traced back to bird feed.

“Bird feed, kind of dirty stuff,” Spiel noted. “Has lots of weeds in it.”

The Extension office asked anyone who sees Palmer amaranth to contact them immediately. Much like invasive species work, quick responses can tamp down an issue before it spreads.

“Everyone’s heads are up and they’re looking for it. We found three plants so far, and none of them have made seed in the field so far,” Seipel said. “We’ve gotten them out early enough because they’re not quite adapted to Montana’s conditions yet. So the more we do that, the more we can keep it under wraps.”