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Weed & Pest

The Tumbleweed Law – Part Two
By Slade Franklin, Wyoming Weed and Pest Coordinator

    The life of the tumbleweed law was short lived. In 1903, representatives from Albany County successfully argued during the legislative session to repeal it. Their objective was supported and championed by several groups and individuals in the agricultural community, but none more outspoken then Dr. H.L. Stevens from Laramie.
    Dr. Stevens was a practicing medical doctor who also operated a ranch in Albany County. His community involvement included serving as a University of Wyoming Trustee and a Trustee on the College of Agriculture in 1903. Dr. Stevens and his supporters were opposed to the initial legislation in 1895 and successfully petitioned for the repeal of the law in 1903 so Russian thistle could be planted and studied as potential livestock forage. Dr. Stevens argued through the state’s newspapers that if the plant was cut and cured, it would “…prove good and digestible fodder for sheep and cattle.” After the 1903 legislative session, the Laramie Republican quoted Dr. Stevens opinion on the repeal of the law as, “…quite gratified by the action taken by the legislature to repeal the law requiring its (Russian thistle) destruction.”
    Not all University of Wyoming staff agreed with Dr. Steven’s opinion. Most notably was Aven Nelson, University botanist, future University of Wyoming President and founder of the Rocky Mountain Herbarium. Mr. Nelson, one of the original five faculty members at the University, was significantly involved throughout the state in identifying and urging the extermination of Russian thistle in 1894. He believed Russian thistle represented, “…the case where an ounce of prevention is worth a pound of cure.”
    During that year, Mr. Nelson published the Wyoming Experiment Station’s first “press bulletin” aimed at assisting landowners throughout the state in the identification and control of Russian thistle. He was also an original supporter of the 1895 law, although he believed it fell short when it didn’t appropriate any funding for preventative measures.
    In addition to supporting the passage of the 1895 legislation, Aven Nelson published “The Worst Weeds of Wyoming and Suggested Weed Legislation,” in the Wyoming Agricultural Experiment Station Bulletin 31, published December 1896. In the bulletin Mr. Nelson listed 50 plants that were by nature “weedy” and posed a potential threat to Wyoming’s agriculture.
    The first specie listed in the bulletin was Russian thistle, to which Mr. Nelson states, “As it is intended to consider the weeds of this list in the order of the danger they present to our agricultural interests, the Russian thistle is placed first for the danger it threatens is both real and imminent.”
    He goes on to state, “Wyoming cannot afford to delay in this matter; the pest is well established within our borders, and will, in another season or two, be entirely beyond our control.” Near the end of the bulletin, Mr. Nelson states his opinion on Dr. Steven’s desire to cultivate Russian thistle by writing, “Some claims have been made for it as a forage plant, but its value in that direction should have no weight whatever when it is understood that it has no advantage over many others with no noxious qualities.”
    Unfortunately Aven Nelson did not win the battle over Russian thistle in 1903, and many of his fears concerning Russian thistle came true.
    Today Russian thistle is “well established within our borders” and can be found in every corner of the state. It is often the first plant to grow in areas where there is disturbance, or in thick patches along the railroad right-of-ways. On a windy day in the fall and winter it’s hard to find a barbed wire fence that isn’t buried under the skeletal remains of the summer’s growth.
    Furthermore, most agronomists today agree with Aven Nelson’s opinion that Russian thistle is, at best, a poor to moderately beneficial forage crop. North Dakota State University bulletins (A-125) states, “Russian thistle should be regarded as an emergency feed crop that may be used when there is an extreme shortage of feed, and not as a desirable feed for use under normal conditions.”         
The best case and point to support this minimal benefit is during the 1930s Dust Bowl, where Russian thistle was credited with saving the beef cattle industry when no other forage options were available. That, however, is a different story for a different day in the life of the tumbling tumbleweed.

Powell – On July 17, the Powell Research and Extension Center hosted its field day to highlight the research projects being conducted at the 220-acre facility, hosting 100 area producers and community members, as well as UW President Tom Buchanan.
    “This is the 150-year anniversary of the Morrill Act, which created the land grant system. The University of Wyoming is the only land grant school in the state of Wyoming,” commented Buchanan at the event. “A big part of the reason why UW has such a strong and growing commitment to agriculture and will continue to have that commitment into the future is because of the Morrill Act.”
    At each of the experiment stations across the state that operate in conjunction with UW researchers, a variety of projects are conducted annually to address the needs of agriculture in their regions.
    “While we were sitting in a regional crop improvement meeting, the growers asked for information on incorporating chemical weed control methods into the soil,” explained Director of the Wyoming Agricultural Experiment Station Bret Hess.
Weed interests
    As a result, Andrew Kniss, UW plant sciences professor, tackled a study titled Evaluation of Mechanical Incorporation Equipment for Dry Bean Herbicides. The study was funded by the Wyoming Crop Improvement Association and the Wyoming Seed Certification Service.
    “This study looks at mechanical incorporation methods,” described Kniss. “One of the issues we have with dry bean production, particularly in this area where we don’t have a lot of overhead irrigation, is that we have to utilize mechanical incorporation. We have to stir the herbicide into the soil in order for it to be effective.”
    “In this study we applied Eptam plus Sonalan over the entire study,” explained Kniss. “We came in with different kinds of incorporation equipment. We also utilized one pass of that incorporation equipment versus two passes.”
    Kniss added that, if only one pass of equipment to incorporate herbicide into the soil is necessary for effective weed control, producers would be able to save money.
    A roller harrow, Vibra Shank with sweeps, Vibra Shank with points, S-tine and disk were utilized to incorporate the pesticide to approximately four inches deep.
    “Primarily, we are interested in hairy nightshade as our key weed species,” commented Kniss, noting that the field exhibits a high population of sunflowers in its second year.
    The first year of the study also evaluated control of redroot pigweed, green foxtail and wild buckwheat.
Initial results
    While the study results published in this year’s Wyoming Agriculture Experiment Station Field Days Bulletin are only preliminary, Kniss noted that weed control was worst when a roller harrow was used to incorporate herbicide.
    “Two passes of the incorporation implement only increased weed control significantly more than one pass when the roller harrow was used,” wrote Kniss. “However, there was a slight trend for better redroot pigweed control with two passes compared to one pass of several implements.”
    In general, the Vibra Shank with points tended to control pigweed better than the implement with sweeps, and Kniss speculated that the effect was probably do to the difference in soil mixing due to the depth or action of the implement.
    Only very early data has been collected for the second year of the study.
    “The results that we are seeing from this year’s study are not necessarily matching up with last year,” added Kniss. “That is one of the reasons we do multi-year research here at the experiment centers.”
This year
    In the second year of the study, Kniss said, “We didn’t get very good weed control in these plots, but as part of weed research, that is part of the game. We can’t tell what works and what doesn’t unless we start with some really weedy fields.”
    By allowing the field to go to seed in 2011, the first year of the study, and additionally seeding the field with nightshade prior to planting, Kniss achieved a “weed jungle.”
    Kniss speculated that the decreased efficacy of weed control in the second year of the study may be a result of two factors. Increased weed density and decreased moisture during the spring likely affected efficacy of herbicide.
    “This year, I think we have a good population of weeds to look at, so we will be able to get some really good data this year,” noted Kniss. “We also seem to have better weed control when we have some overhead incorporation in addition to the mechanical corporation.”
    “After this year, we will know a lot more,” he added. “We will look at the second pass and see if there are any general trends as far as recommendations for which type of mechanical equipment to use for weed control.”    
    The second year of the study will also look at yield data to address competition of the beans and weed populations.
    For more information on this study, contact Andrew Kniss at This email address is being protected from spambots. You need JavaScript enabled to view it. or 307-766-3949 or view the Wyoming Agriculture Experiment Station Bulletin at 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..

Spiering emphasizes the ‘ships’
Powell – Powell Research and Extension Center Advisory Board member Kelly Spiering addressed participants during a tour of the facility of July 17, mentioning that, without relationships between the center and its constituents, resulting research was less valuable.
    “The buzzword we should be thinking about is ‘ships,’” commented Spiering. “That means friendships, relationships and partnerships. Relationships are the keys to success.”
    Spiering added, “If researchers just do research without thinking about the people that it is going to affect, it loses value. The benefit that they can provide in the larger scope makes the research valuable for all.”
    In forming relationships with the public, Spiering added that the Powell Research and Extension Center could be more productive and a more valuable asset for producers in the area and across the state.

Cody – Thirteen western states sent the leaders of their state departments of agriculture to the 2012 Western Association of State Departments of Agriculture (WASDA) summer meeting in Cody on July 16 – 19 to discuss those issues that comprehensively affect the West.
    “Being a regional group of state departments of agriculture, we have a lot of things in common,” commented Wyoming Department of Agriculture Director and WASDA Chairman Jason Fearneyhough. “We see similar issues in the western states dealing with BLM and Forest Service, and a lot of our issues are natural resource based.”
    “One of the things we are working on is the invasive species issue,” he added.
Common ties
    “The invasive species that we deal with in Wyoming are far different than those that they deal with in Hawaii, but nonetheless, they are invasive,” explained Fearneyhough. “It would be really beneficial to have a resource for states to be able to deal with invasive species with less red tape.”
    For the last year, WASDA has discussed obtaining funding in the form of block grants for states to deal with invasive species, and Utah Commissioner of Agriculture and Food Leonard Blackham has been very involved in the effort.
    “Invasive species is a big issue, and it’s a big issue throughout the nation. Every state has an invasive species,” commented Blackham. “Sometimes it is cheat grass, like we have in the West, sometimes it is the invasion of pinion juniper, sometimes it is a pest like the bark beetle and sometimes it is a disease – invasives include all of those things.”
    “Here in Wyoming, I can name 100 different weeds and the quagga and zebra mussels we could deal with if there was more funding,” added Fearneyhough.
    “We need to be really aggressive,” Blackham noted. “What we are promoting is a national initiative.”
State level involvement
    “We are encouraging the federal government to do block grants to the states, and at the state level, direct money to invasive species actions,” explained Blackham.
    By allowing individual states to distribute money, he said that more money will be actually implemented on the ground.
    “States always seem to get more money on the ground. We are proposing that 80 percent of the money has to hit the ground,” Blackham added. “Because the processes in the states are not as cumbersome, we seem to get more money on the ground for projects.”
    Further, with the partnerships that exist between local conservation districts, university extension programs, the public and state governments, bringing invested parties together to tackle tough challenges is easier.
Wide reaching benefits
    “This is the proper thing to do,” said Blackham. “Improving the landscape will improve water quality, water quantity and will reduce fires.”
    Using cheat grass as an example, he said that, because it forms a monoculture, cheat grass makes the land more susceptible to fire and the negative downstream affects that follow.
    “The fact is, this money may save three or four times as much down the road if we can control species and reduce catastrophic fires,” he said. “We think this is a very wise investment to make, and that is how it needs to be looked at – as an investment.”
    Additionally, in many western states where public land dominates the state, much of the money will be spent improving land that the federal government has an obligation to take care of already.
    “On private lands, the more we can help farmers and ranchers get the job done, the better able we are to keep food more reasonably priced,” Blackham noted.
Promoting the idea
    At the WASDA summer meeting, the concept of providing block grants for invasive species management was discussed extensively, and the organization is working to encourage other groups to promote the issue.
    “The National Association of Conservation Districts is supporting this effort, and the Western governors have a statement supporting it,” Blackham said. “We hope to take the idea of a block grant to get these groups behind it.”
    WASDA members are also working to get support from western congressmen.
    “We all know this invasive issue is getting more and more difficult because of the way we live and world activity,” Blackham said. “I think this is a very proper role and it is surely needed.”
    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..

WASDA members meet
Cody – Over the course of the three-day 2012 Western Association of State Departments of Agriculture summer meeting, attendees discussed issues, met with the National Association of State Departments of Agriculture (NASDA) and the Western U.S. Ag Trade Association and were given an overview of the Wyoming agriculture industry.
    WASDA members include Alaska, American Samoa, Arizona, California, Colorado, Guam, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming.

Sheridan – For the first time, ventenata grass and medusahead were discovered outside the Great Basin last year in Sheridan County. Both grasses are invasive and present problems that outweigh the impacts seen from cheatgrass in the state.

“When I speak to weed scientists in Idaho, Oregon and part of California, they say they would trade every acre of ventenata and medusahead to get cheatgrass back,” said Brian Mealor, director of University of Wyoming’s (UW) Sheridan Research and Extension Center.

On June 14, the Northeast Wyoming Invasive Grass Working Group hosted a tour where over 80 weed specialists, landowners and others from five states gathered to learn more about the two unique and concerning invasive species.

“There is a lot of interest in these species, particularly since this is the first occurrence of both of these species outside the Great Basin,” Mealor said. “This was really a good opportunity for people to know what to look for and learn more about these species.”


Both ventenata grass and medusahead dramatically reduce forage quality of rangelands.

“In heavily infested areas, ventenata and medusahead can reduce forage quality by 70 percent,” Mealor said. “If we get livestock on it early enough – when there isn’t much else to choose from – they’ll use it. But, these grasses sequester silica out of the soil, which is basically sand. It’s no wonder why cows don’t want to eat it.”

“The forage value of medusahead is really limited, too. It has a stem and pointed seed head. There are almost no leaves on it at all,” Mealor said.


When looking at ventenata grass, Mealor explained that it is dispersed across 750,000 acres in northeast Wyoming.

“Last May, we didn’t think ventenata existed in Wyoming,” he said. “By the end of October, when we connected the dots, we have about a 750,000-acre distribution of it.”

The quick recognition of the species was due to the vigilance of landowners, who were willing to look for the plant and contact weed specialists when they found it.

“Ventenata is much more widespread than we originally thought,” Mealor added.


While ventenata grass is concerning, Mealor noted that medusahead causes him considerably more concern.

“Medusahead is, by all accounts, more difficult to control than the other grasses,” he said. “This has been on our radar over the last 10 to 12 years.”

Over the last decade, Mealor said he has deployed survey crews, primarily in Uinta and Lincoln counties, to see if medusahead breached Wyoming’s borders.

“The nearest documented location of medusahead to Wyoming was on Utah State University’s Hardware Ranch, 28 linear miles from the Lincoln County line,” Mealor explained. “When it cropped up in Sheridan County last year, we were all scratching our heads on how it got there.”


Medusahead has long awns that get longer as the plant starts to mature.

“As the inflorescence starts to mature, the awns on the bottom portion get noticeably shorter than the ones on the top,” Mealor explained. “It looks like it had a haircut.”

At the same time, the awns are long, barbed and rough. They are also sharp and twisted, making it even less palatable for livestock.

“Medusahead is bright green in color, and it’s just now starting to turn neon green,” he said. “We’re trying to capitalize on that to get out and identify where it’s at.”

Addressing the species

“We were hoping to never deal with ventenata or medusahead. Now, we have to decide what our strategy and course of action should be,” Mealor said.

As of June 7, three locations northwest of Sheridan and near the Montana border have documented medusahead populations.

“At this point, the three known populations are relatively small, but we don’t know if they reflect the full species distribution,” he continued. “If they do reflect full distribution, we hope to do aggressive treatments to eradicate the species.”

To aggressively target both medusahead and ventenata, the Northeast Wyoming Invasive Grass Working Group has banded together, bringing together a number of land management agencies, local governments, landowners, university researchers and Extension professionals.

“Imagine if we had found the first two or three occurrences of leafy spurge in the state and were able to get rid of it. Think of how much effort, money, headaches and time we could have saved,” Mealor commented. “Look at Canada thistle, Russian knapweed, salt cedar and the whole list of invasive species. What if we would have found those early? Finding these species early gives us a great opportunity.”

He continued, “I think we need to employ every tool we have to try to get a handle on these species.”

End game

Most importantly, with new invasive species creeping into the state, Mealor said, “We can’t be out all the time everywhere. Ranchers are our biggest asset in combatting these invasive species.”

With discussion on a management plan moving forward, he also notes that the working group is currently working on a survey to determine just how widespread ventenata grass and medusahead are in the state.

“Anyone who thinks they have medusahead or ventenata needs to call someone – weed and pest, conservation districts, me or Extension,” Mealor emphasized. “The opportunity we have to address this problem early before it gets too big is huge.”

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..

As landowners around the state are preparing for the winter, Wyoming Weed and Pest urges Wyomingites to be vigilant in watching for invasive species on their property.

In particular, Yellow flag iris and musk thistle are at the top of the list that producers may be unfamiliar with at this point.

Yellow flag iris

“This summer, Teton County signed an emergency declaration for Yellow flag iris,” says Wyoming Weed and Pest Coordinator Slade Franklin. “This is plant that we don’t know much about.”

“Yellow flag iris will most likely show up in high water areas,” Franklin says, citing riparian areas and waterways.

Yellow flag iris, also known as paleyellow iris, yellow iris or yellow flag, is included on state weed lists in Connecticut, Massachusetts, Montana, New Hampshire and Washington, and USDA’s Natural Resources Conservation Service also lists the plant as invasive.

“Yellow flag iris displaces native vegetation along stream banks, wetlands, ponds and shorelines,” says the King County Noxious Weed Control Program out of Washington.


Yellow flag iris is a perennial plant that creates dense stands. It can grow to five feet tall and has numerous thick, fleshy rhizomes.

The flowers of the plant are yellow and described as “showy.” They occasionally have brown to purple veins at the base of the petals, and several flowers can occur on each stem.

The plant typically blooms from April to August, and it may remain green all winter in mild years.

The leaves of Yellow flag iris are broad, flat and pointed. They are folded and overlap one another at the base.

“When not in flower or seed, Yellow flag iris can be confused with cattails, which are round at the base and taller than yellow flag iris,” adds King County.


To treat Yellow flag iris, integrated pest management (IPM) is a preferred method. The IPM approach allows selecting from a range of control methods to target the management needs of individual sites, according to King County.

In addition, they mention that individual plants can be effectively dug up. However, in manual control methods, collection of rhizome fragments is important. It is also important to minimize disturbance to avoid creating seed germination opportunities.

King County suggests looking for seedlings starting in late winter and digging up small, isolated patches. Plants will likely be located in high water areas along river and lake shorelines, wetlands, ditches and in wet pastures.

Musk thistle

In addition to Yellow flag iris, Franklin mentions, “Musk thistle has exploded in this state and across the West. Musk thistle is all over the place in Wyoming.”

He also notes that the prevalence of Musk thistle this year was higher than he has seen ever before.

“For people with one or two plants, musk thistle can be effectively dug up or knocked down,” Franklin says. “There are also herbicide treatments.”

Musk thistle is capable of appearing anywhere, and it can be a big problem once it is established.

Looking at the plant

Musk thistle can grow to six feet tall. The upright stems of the plant are winged and can be single, multiple or highly branched.

The rosette leaves of the plant are elliptic to lanceolate and pinnately lobed, with each lobe ending in a spine, according to North Dakota Weed and Pest.

Flowers of Musk thistle are deep rose, violet or purple in color, though occasionally white flowers may be seen. They also feature characteristic brown bracts that resemble a pine cone.

North Dakota Weed and Pest also notes that Musk thistle is an aggressive species that can form extremely dense stands, which reduce the ability of native pasture and rangelands to compete by suppressing desirable growth of plant species. At the same time, plants are not palatable to livestock, making their invasion more aggressive.

“Cattle generally will not graze Musk thistle, and sheep will only consume the plant during the rosette growth stage,” they continue. “However, some studies suggest that cattle, domestic sheep and goats may consume Musk thistle flower and seed heads.”

However, concerns about livestock spreading the seeds of the plant have led to a recommendation against grazing as a control mechanism.

Landowners who suspect the presence of Yellow flag iris, Musk thistle or any other invasive species on their property should contact their county weed and pest office for assistance in determining the most effective treatment strategy.

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..