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Noxious Weeds

Jackson – This year’s Wyoming Weed and Pest Conference was held in Jackson from Oct. 28-31 and focused on the topic of invasive species and their impacts across the West.

“This year, we were able to have a good conference in Jackson,” says Wyoming Weed and Pest Coordinator Slade Franklin. “It worked out well and working with the North American Invasive Species Management Association was great.”

Franklin noted, “One of the most interesting topics was the discussion on invasive grasses,” Franklin continues. “Obviously we hear a lot about cheatgrass, but there are other species that we have had discussions on.”

Grasses such as medusahead, ventenata grass and buffelgrass were all topics of focus.

“We invited individuals from other states to talk about the challenges of controlling these grasses,” he says. “These species are coming closer and closer to the Wyoming line.”

These invasive species, noted Franklin, have the potential to create problems similar to or worse than cheatgrass infestations.

“There is some talk about how cheatgrass has early spring forage value,” he explains, “but with medusahead, we don’t see any forage value at all.”

The species creates a mat of grass similar to cheatgrass, resulting in high fire potential and take-over of ecological systems.

“These grasses are already present in Idaho and Nevada, and they have taken over,” Franklin adds. “They are slowly progressing toward the east.”

The result of continued movement of equipment putting in pipelines, oil developments and power lines, as well as movement of farm equipment means there is a higher potential of spread of these grasses.

“As we see more equipment moving around, it is certainly something that we should be concerned about,” Franklin comments.

Next year’s meeting will be held in Rock Springs on Nov. 3-5.

Look for more from the Wyoming Weed and Pest Conference in next week’s paper. Saige Albert is managing editor of the Wyoming Livestock Roundup. Send comments on this article to This email address is being protected from spambots. You need JavaScript enabled to view it..

Thermopolis – The Hot Spring County Weed and Pest Resource Tour on July 14 showcased the success of the agency in nearly eliminating salt cedar from the Cottonwood Creek watershed over the past six years.
Marvin Andreen, former supervisor of the Hot Springs County Weed and Pest, said the Watershed Improvement District (WID) was formed in 2005, and he explained that a group of ranchers and agency leaders formed the WID after touring the Cottonwood Creek/Grass Creek Coordinated Resource Management area and noticing a problem with the prevalence of salt cedar.
“When we first started, there were between 700 and 900 acres of salt cedar on between 50 and 60 miles of Cottonwood Creek,” said Andreen. “I worked with the NRCS and WID to put together a grant through the Wildlife Trust Fund.”
The grant started as a five- to 10-year plan to remove all salt cedar in the drainage, but it bloomed quickly.
Hot Springs County Weed and Pest Supervisor Bob Cunningham said, “The goal behind this project is to make the land look like it did in the past, and to get the native grasses re-established.”
“Right now, virtually all the salt cedar has been taken off Cottonwood. We’re still working on a couple of branches and tributaries,” said Andreen.
Amy Anderson, Habitat Extension Biologist for the Wyoming Game and Fish Department and Natural Resources Conservation Service, added that in three years the project’s partners did 1,203 acres of salt cedar removal.
“It has been a huge partnership,” continued Anderson. “We’ve built partnerships between agencies and landowners and managed to work really well together to accomplish this project.”
Following the initial mechanical removal of salt cedar and Russian olive, chemical treatments were applied by the Hot Springs County Weed and Pest to more completely eradicate the invasive species, and to make an effort to eliminate other noxious weeds, such as white top and Russian knapweed.     
The benefits of the removal of salt cedar and Russian olive along Cottonwood Creek are multi-fold and involve forage, livestock and water supply. After salt cedar and Russian olive were removed, small stand of cottonwood trees began appearing through area, and a project to revive the cottonwood population began.
“We didn’t really even know these cottonwoods were here,” said Anderson, referencing a stand of trees at Sand Draw Junction. “We’re hoping the cottonwoods will begin to reseed themselves, and we’re doing some plantings to get the seed source replaced.”
“The cottonwood project started in 2008. Since we started, this project has taken off in a big way,” said Anderson. “We’re working on Cottonwood, the Shoshone River, parts of Owl Creek and the Big Horn, Gooseberry, the Greybull River and Shell Creek.”
BLM Invasive Species Coordinator CJ Grimes said, “If you have a dense patch of salt cedar already here, you won’t get establishment of cottonwood, even if all other conditions are perfect.”
The cottonwood project looks at getting rid of noxious weeds and establishing stands of cottonwood trees along the creek.
Additionally, with the removal of salt cedar and noxious weeds, native grasses have begun to grow again.
Wyoming Department of Agriculture Natural Resources and Policy Division Eastern Wyoming Program Coordinator Larry Bentley said, “A few years ago, the salt cedar was so thick that you couldn’t ride or walk through it anywhere, except where cows had been. You have to imagine that it was basically almost a monoculture on the creek bottoms from bank to bank.”
After the removal of salt cedar and Russian olive, wildlife populations also began to rebound.
“There has been an increase in the number of migratory birds and native birds moving back into the area,” said Bentley. “On the Shoshone River, the second day we started our project 35 wild turkeys moved in that hadn’t been there before. There is a great benefit to the wildlife.”
Anderson added, “A decrease in wildlife occurs when you seen an increase in Russian olive, because access become difficult for migratory birds. You also see an extreme depression in the number of insects in stands, so the birds stay away.”
Russian olive seeds provide a good food source for wildlife, but the density of the cover and formation of a monoculture – or single species of plant in the area – is not good for livestock or wildlife, explained Anderson.
“We are pushing this to improve the riparian systems,” said Anderson. “These greener areas attract wildlife.”
Grimes commented, “We are trying to eliminate and manage the invasive species that compromise the habitat and encourage the native species that the wildlife are more accustomed to.”
A high prevalence of salt cedar and Russian olive in a watershed is also detrimental to the water supply and availability.
“Each plant takes 15 to 20 gallons of water a day out of the system. It doesn’t take long to dry up a creek when you have 50 miles of salt cedar,” said Bentley.
Anderson added, “Everyone is excited to be able to access their creek bottom. It is important for grazing and wildlife access.”
Regardless of the current successes of the project, both Andreen and Cunningham agree that the project doesn’t end here.
“This isn’t a one-and-done type of project,” said Andreen. “It’s a long-term project with a lot of management issues that will have to take place, but I really think we have things going in the right direction with a bang.”
“Hopefully in the next three or four years it will be manageable enough that the landowner can maintain it at a low cost with less intense labor,” said Cunningham.
Saige Albert is assistant editor of the Wyoming Livestock Roundup and can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..

Lingle – Andrew Kniss, University of Wyoming associate professor in weed science, said his job is to find weeds and the best way to kill them, but during the 2018 Forage Field Day, held June 12 at the James C. Hageman Sustainable Agriculture Research and Extension Center in Lingle, Kniss asked producers to consider why they control weeds and what the impact of not controlling weeds may be. 

“If we don’t control weeds, will we see quality impacts or lower yields?” he asked.

Organic production

Kniss assessed the question by first compared a recent study that looked at organic and conventional production. 

“Almost every crop shows a penalty to organic production because these producers don’t have the same access to fertilizers or synthetic pesticides, which is a big deal,” he said. “We find organic crops will produce 70 to 80 percent of conventional crops.” 

“Most interestingly, in alfalfa production, however, organic hay producers are producing yields almost exactly the same as conventional management,” Kniss commented. “Other hay producers see almost 20 percent higher yields than conventionally managed fields. All hay is right in between, about 10 percent more than conventional hay.”

“This is very different than almost every other crop, so we asked ourselves, what’s going on?” he continued. “My thought is, they harvest weeds. Organic producers see a benefit because they’re harvesting the weeds, as well as the alfalfa and hay crop.” 

Kniss continues the impact is further demonstrated by looking at the impacts of weed management on alfalfa yields. 

“Studies show, out of total forage yield, a herbicide treatment in the fall or springs shows impacts yield,” Kniss explained. “In two out of three sites, yield was reduced when herbicide was applied. The study did not see a response of increased yield to herbicide application.” 

Managing weeds

Depending on the goals of an operation, Kniss further commented perhaps the right answer would be to let weeds grow to increase forage production.

“We should think through what our tolerance should be for weeds in our forage, because weeds can actually increase the amount of production we harvest,” Kniss said. 

The reason weeds are controlled in alfalfa and hay fields is for quality, he continued. 

“The same study showed us, when we have two different herbicide treatments for weed control, we didn’t see a change in overall yield, but the yield of alfalfa changes,” Kniss said. 

Kniss noted the amount of alfalfa per acre was 0.6 tons, but when treated with herbicides, alfalfa production doubled. 

“We’re producing two tons per acre, and it’s either alfalfa or something else,” he explained. “We manage and get rid of weeds to maintain quality.”


A 1987 study looked at one aspect of alfalfa quality, showing dramatic declines in quality when more than 15 percent of an alfalfa stand is weeds. 

Data from a Steve Miller study in 2002 looked at the protein and relative feed value (RFV) of alfalfa stands ranging from less than five percent weeds to greater than 40 percent weeds. 

A broadleaf weed infestation of less than five, 10 to 15 and 20 to 30 percent weeds resulted in protein percentages of 23, 22 and 21 percent, respectively, and RFV of 157, 148 and 141, respectively. When the weed composition increases to 40 percent, protein drops to 19 percent and RFV hits 136. 

Green foxtail in forage crops has nearly identical impact, dropping the protein to 14 percent and RFV to 110 at greater than 40 percent infestation. 

“Quality is why we’re interested in managing weeds,” Kniss said, “but we have to consider if we’re getting paid on quality.” 


“What we do with our alfalfa dictates how much tolerance we might have to manage weeds,” Kniss said.

For example, Kniss said if the alfalfa crop is going to be used to feed cattle, a weed-free crop might not be necessary.

“Some weeds have high nutritive content, and some weeds have less impact on quality than others,” he explained. “Unfortunately, our most common weeds give us the big hit on quality.”

Common lambs quarter and green foxtail negatively impact forage quality, but kochia is relatively good quality forage. 

“We have to watch kochia during drought years, however, because it accumulates nitrates, so it’s dangerous to feed,” Kniss said. “Weeds also decline in quality as they get more mature, so we must also consider timing of harvest when we have weeds that get stemmy and decrease quality.” 

Kniss encouraged producers to answer these questions for themselves and determine their tolerance for weeds.

“When we’re decided whether to control weeds, we need to keep in mind things like toxic and noxious weeds or weeds that can get out of control quickly,” Kniss said. “We also needs to keep in mind our marketing strategy, which may change our tolerance for weeds.”

Saige Albert is managing editor of the Wyoming Livestock Roundup. Send comments on this article to This email address is being protected from spambots. You need JavaScript enabled to view it..

Douglas – In a plot north of Douglas, the Converse County Weed and Pest debuted a bacterial cheatgrass control trial on Oct. 21.

“This is the first time this bacterial control has been tried in Wyoming,” commented Converse County Weed and Pest District Supervisor Cheryl Schwartzkopf. “We are very excited.”

The trial comes after USDA Agricultural Research Service Soil Scientist and Microbiologist Ann Kennedy isolated and propagated a strain of bacteria capable of naturally inhibiting cheatgrass.

“This organism inhibits cheatgrass, medusa head and jointed goat grass,” explained Kennedy. “We have other organisms that inhibit different consortia, but this is specific to cheatgrass.”

Project beginnings

When Schwartzkopf heard about Kennedy’s bacteria project, she jumped on the opportunity to debut the bacteria in Wyoming.

“We actually found this bacteria and this phenomenon when we looked at poor growth in winter wheat in the early spring,” noted Kennedy. “We found that a lot of the organisms clinging to the wheat were inhibitory to wheat and other grass weeds.”

Though her team started working with wheat, they soon began looking at other grasses, and the bacteria that targets cheatgrass, medusa head and jointed goat grass emerged.

The bacteria are desirable because they are not dangerous to other plants, animals or humans.

“Our goal was to find an organism that was benign in soil,” Kennedy said. “It has always been a big deal for me to see if we could find something that would survive for a little bit but not forever. It also doesn’t inhibit other plants.”

Using bacteria

In Converse County, the bacteria were utilized in three different applications. 

The bacteria are frozen, lyophilized and stored in vacuum-sealed bags after being grown in the lab.  

“After we remove the oxygen, the organisms will survive for a very long time if they are kept cold,” Kennedy explained, noting that after oxygen is introduced, 

The bacteria can mixed with water or herbicide and sprayed on fields, or it can be coated on seeds and planted.

“We like to spray the bacteria the best,” she said. “It is very inexpensive and easy to do.”

For about one dollar an acre, the bacteria are applied to rangelands. A plot in Converse County, north of Douglas, was treated using by mixing the bacteria with Plateau herbicide and sprayed.

“We see really good reduction and really good activity when we apply with herbicides,” Kennedy commented. “The herbicide targets the above-ground growth of the cheatgrass, and the bacteria gets the seed bank.”

Because plants that are already growing can simply grow new roots in a different location and the bacteria aren’t very motile, Kennedy explained that herbicide is necessary to eliminate emerged cheatgrass.

Seed coating

Additionally, the Converse County trial also utilized seed coated with the bacteria. 

“When we put the bacteria on wheat seed and drill it in, it is nice and comfortable in the soil,” Kennedy explained. “On the surface, there are drying conditions, which can kill the bacteria.”

“If the organism doesn’t survive, it doesn’t work,” she added.

Rather than drilling seed, the plot north of Douglas utilized broadcast crested wheatgrass seed.

“We are using crested wheatgrass seed and rice in this trial,” noted Kennedy. “We applied the bacteria to the seed, and it will be distributed using a whirly-bird.”

To coat the seed in Douglas, the bacteria were mixed with water and distributed into gallon-sized plastic bags of seed, which were then agitated by volunteers. 

“In our facility, we use a cement mixer to coat the seed,” Kennedy explained. “We try to do these projects inexpensively.”

By utilizing native plant seeds with the bacteria, Kennedy said that natives regrow as the cheatgrass is eliminated, reducing the likelihood of re-infestation of cheatgrass or other weed species.

“The real big thing is that if we just apply bacteria, we may get rid of cheatgrass,” she explained, “but either the cheatgrass comes back, or another weedy species comes in. We have to get those natives back into the rangeland system.”

Other options

In Douglas, rice was also used.

“Rice is something we have been talking about using as a potential way to aerially apply bacteria,” Kennedy said. “It is heavier than seed.”

After being distributed, the rice absorbs water and dissipates, while the bacteria works into the soil.

“Rice is not ideal because birds can eat it when it is still dry,” she said. “It gets stuck and explodes in their gullet.”

Other options include using products like spaghetti or small noodles.

She added, “The best results we’ve gotten are when the bacteria are applied every three years because it keeps enough of the organism in the system.”

Trial results

The bacterial trial will occur over the next three to five years. Results are not seen until after that period because the bacteria must grow in the soil.

“The first trials we put out, people were very angry with us when they didn’t see results after the first year,” Kennedy said. “Growers came back later and said, ‘Where we put the bacteria, there is no cheatgrass.’ We realized it would take a little longer to see results.”

Since deploying trials, she noted that successful elimination of cheatgrass has resulted.

“We put out plots in the 90s on wheat, and we saw really good reductions,” said Kennedy. “We have seen a 50 percent reduction in cheatgrass – without adding any seed or using any follow-up treatments – on plots that we applied in 2009 and 2010.”

Treatments have been applied to plots across the northwest U.S., and positive results have been seen thus far. 

While the final approvals are being processed by EPA and other regulatory agencies before the bacteria can be sold commercially, Kennedy noted that within the next two years, they hope to see some commercially available product. 

Saige Albert is managing editor of the Wyoming Livestock Roundup and can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..

Mechanism of inhibition

In working with bacteria to inhibit cheatgrass, Agricultural Research Service Microbiologist and Soil Scientist Ann Kennedy started to figure out that the bacteria are working in the membrane or cell walls of the plants to break down components of those cellular structure, effectively killing the cheatgrass seed.

“The bacteria disconnect certain carbons chains in the lipids of the cell wall or cellular membrane of the cheatgrass roots,” explained Kennedy. “It doesn’t allow the plant to form a good membrane, the root cells don’t grow, roots are stunted, and the activity of cheatgrass is reduced.”

Because each plant has a unique set of carbon chains within their cell walls and cell membranes, the bacteria is specific to the three target species.