New invasive weed spotted in county

Tom Milstead/torrington telegram Jenna Meeks, Assistant Supervisor for Goshen County Weed and Pest, warns producers about the dangers of Palmer Amaranth during the High Plains Crop Summit on Nov. 26 in Torrington, Wyo.

TORRINGTON – With another growing season just months away, farmers in Goshen County need to be on the lookout for invasive Palmer amaranth in their fields. 

Jenna Meeks, Assistant Supervisor of Goshen County Weed and Pest, warned producers at the High Plains Crop Summit last month that Palmer amaranth has been spotted in Goshen County, and that if left unchecked it could present a serious issue for local farmers. 

“My original title was ‘Set your pride aside,’” Meeks said. “As we know, farmers are very proud and might not want to admit to themselves or other people that Palmer is on their place or that they’ve seen it. They might even get a little defensive. 

“Palmer doesn’t care. It has no respect for anybody’s pride or the way things have always been done. It’s going to take a concerted effort to make sure it doesn’t spread.”

Palmer amaranth is an aggressive weed that can grow up to three inches per day, according to a report from North Dakota State University. It can grow up to eight feet tall and rapidly take over production fields. 

In some plots in the Midwest, it has resulted in 90 percent or more yield loss, Meeks said. 

“It’s a new weed within this region,” she said. “It is confirmed in Goshen County and it has been confirmed in Nebraska for the last few years. It was found in Goshen County in four isolated spots, if not other places. 

“It is new to this area. The Palmer that is in the Midwest has herbicide resistance to seven different modes of action. The theory is that the Palmer that is here now has not developed those resistances yet.”

One of the most dangerous things about Palmer amaranth is the rapidity with which it can produce seeds. Meeks said it can begin producing seeds when it’s just four inches tall – it grows up to three inches per day – and larger specimens can produce over 1 million seeds per plant. Those seeds, Meeks said, are easily transferable. 

“My soapbox is that if you’re buying product or if you’re making trades for products – like if you going to give someone something and they’re going to spread manure on your place, I would be very cautious,” Meeks said. “Even if you know these people very well, even if you are friends, to have some due diligence earlier in the season and make sure Palmer isn’t on their property. 

“If it’s anywhere, it will move quickly. The seed is very small. It can get on tires, on animals, even dog fur. If you’re standing here and your dog runs over there and there’s some Palmer, it will have it in its fur and paws. Then it can track into your pick-up and now you’re moving it, too.”

They key to keeping Palmer amaranth under control is to be diligent about identifying it before it becomes a larger issue. 

“My caution is it can move anywhere, no one is safe,” Meeks said. “Even if they tell you their product is weed free or they cleaned their equipment. I don’t want to harbor ill will towards other people in production ag, but I think an honest look at this weed will help us mitigate some spread.”

The local Palmer amaranth can be treated by producers, Meeks said. Herbicide and manual removal are the best methods, but the plant does tend to develop herbicide resistance. 

“Palmer germinates season-long, so one herbicide application doesn’t cover it,” she said. “Pre-emergent application of herbicides will be very important. The seed is viable when the plant is four or five inches tall, so it’s not immediate, but within a small window they could have viable seed. 

“Pulling is an option. Tillage isn’t a great option because you’re going to disturb the seed. Identification is key.”

According to a handout produced by Weed and Pest and the University of Wyoming Extension, Palmer amaranth can be identified by its symmetrical, poinsettia-like leaf arrangement. It has a smooth, hairless stem and notched leaf tips. Leaves sometimes have white chevrons and it can grow to eight feet. It looks similar to redroot and smooth pigweed.

For more information, contact UW Extension at (307) 532-2436 or Goshen County Weed and Pest at (307) 532-3713. 


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