Photo: Kochia in Southwest Montana. © 2020 Delena Norris-Tull
Dr. George Beck, Colorado State University Weed Scientist, interviewed in person by Dr. Delena Norris-Tull, October 24, 2017
Reviewed & approved April 11, 2021
Dr. Beck is now retired but still doing consulting work as Market Development Specialist for Alligare, LLC. Alligare is a post patent herbicide company out of Opelika, Alabama.
Dr. Beck was hired by Colorado State University in 1985 to work on perennial noxious weed issues on rangeland and in pastures. He served on ISAC (Invasive Species Advisory Committee) from 2002-2008 and was chairman for 2 years. In our 1.5 hour interview, he provided me with a brief history of weed legislation at the state and federal levels.
“Currently, about 40 states have Noxious Weeds laws. Every state has a noxious weed seed list.
“At the federal level, the focus is on ‘weeds.’ I served on the Intermountain Noxious Weed Advisory Council (INWAC) and the Healthy Habitats Coalition (HHC) and both groups were trying to improve weed management by the federal government. The federal land management agencies are the biggest problem for weed management because they manage so much land, and weed management has become very political.
“In 1985, I helped with a workshop in Denver to a group of representatives from Federal agencies. Back then, the Colorado weed law was bizarre, but at least we had legislation related to weed management. At that time, some of the Federal representatives, particularly the representatives from the BLM (US Bureau of Land Management) were very arrogant towards us at the state level. One individual said, ‘You cannot tell us what to do, we work for the federal government.’
“Wyoming has had an excellent history working with weed management. INWAC was started by the then Wyoming Weed and Pest Coordinator, George Hittle. INWAC knew an improved federal weed law was needed. We helped write what is still known as Section 2814 (7 U.S.C 2814), the Federal Noxious Weed Act of 1974 (FNWA). In this law, it stated that the Federal agencies must work with the State and local agencies to manage noxious weeds. In other words, the law made it clear that the Federal agencies are not in charge of what we do at the State level and they must collaborate with us.
“The FNWA was repealed in 2000. APHIS (Animal and Plant Health Inspection Service) was already working on the Federal Plant Protection Act that replaced several laws including the Federal Noxious Weed Act of 1974. Section 2814 was the only section saved from the FNWA that was directly incorporated into the newly proposed law.”
“A Congressional bill, H.R. 1485 the Federal Lands Invasive Species Control, Prevention, and Management Act, is currently sitting in the US House of Representatives, waiting for the Senate to write a companion bill. This bill expanded on weeds to include all invasive taxa and would require federal land management agencies to develop invasive species management programs. Spending parameters were outlined that required the Departments of Agriculture and Interior to spend no less than 75% of identified invasive species management funds on the ground to directly control the problems, no more than 15% of those funds could be spent on outreach and discovery, and no more than 10% of the funds be spent on administration.
“About 15 years ago, the National Park Service developed a team concept to facilitate coordinated weed management among the National Parks. For example, there was a team that included Carlsbad National Park, Lake Mead National Recreation Area, and Rocky Mountain National Park. These teams remain active to this day and are called ‘Exotic Plant Management Teams.’ Department of Interior NPS officials provide funds for weed management projects within individual national parks that otherwise do not have direct funds to support – the funding comes out of Washington DC and not the individual parks. This approach has been very successful for NPS but the problem outstrips the capacity to resolve the issue.
“There is a tongue-in-cheek estimate that only about 50% of the people in any Federal land management agency actually do the weed management work. Unfortunately, those not doing the work are often the nay-sayers that can influence the development of appropriate policies that could resolve the problem.
“The term ‘Noxious’ has its founding in agriculture; people long ago recognized certain plants that grew in association with the farming efforts were key problems. Rangeland, however, is dealt with differently than arable lands. Rangeland is expected to have minimal inputs. In other words, there is little money available for improving rangeland and there are little funds made available for managing weeds on rangeland.
“Over the years, we have managed to gain enough attention to weed management concerns, that people at the State and Federal levels and those holding private properties started to listen to our concerns about weed management on rangeland. Additionally, wildlife areas, open space and similar descriptors were adopted to recognize those lands where State and Federal land management agencies were the administrators, or managers, to distinguish from the traditional definition of ‘rangeland’ and thus, make providing for invasive species management funds for such real estate doable in the minds of many decision makers.
“In the 1980s and 1990s, our focus broadened from just using herbicides to control weeds to developing integrated weed management systems – i.e., what changed over the years is how we describe what we are doing and implementing those plans. We learned that when we explained that we’re trying to improve the productivity of rangeland, open space, and wildlife habitat, that’s when people began to listen.”
Cheatgrass concerns: “When we started controlling cheatgrass (with herbicides) in areas where it was beginning to invade, we started seeing native plant species coming back. But on severely abused lands, where cheatgrass had dominated for years, that doesn’t happen. We learned that in those cases, we have to re-seed the rangeland, open space, and wildlife areas with native species to return those areas to productivity.
“We are beginning to learn how invasive weeds alter the soil and subsequently, the native plant communities and how these impacts can be ameliorated. Temporary use of herbicides and other tools to decrease weeds in severely invaded lands, have minimal impact compared to the effects of invasive weeds on the soil systems. But even old stands of invasive weeds can be recovered, but take greater time and effort. The key to success is beginning reclamation and restoration efforts where the native plant community still has a presence, as those areas are easier to recover and cost less money and time to do so.
“In the 1980s, the federal government initiated the Conservation Reserve Program (CRP). This program was an outgrowth of the old farming approach on marginally productive lands that helped create the Dust Bowl. The CRP program provides subsidies to private landowners to take marginal farm land out of production, turn that land back into grasslands. These lands cannot be grazed or farmed and are put back into prairies. If this program had not been initiated, our current concepts of weed management may not have been readily adopted.
“The US Natural Resources Conservation Service (NRCS; formerly the US Soil Conservation Service) demonstrated through the CRP program that native plants will endure longer than non-natives, as native plant communities are better adapted to the grassland/prairie landscapes that formerly dominated much of the central U.S. Marginal farm lands on the Great Plains are better suited to be prairies where, someday, well-managed grazing by livestock and wildlife still will allow for agricultural production.
“In Colorado, we have state-level Conservation Districts. These are the longest-standing fighters of weeds in our state. They are the local connections to the NRCS and the USDA and allow for local input into changes in land management practices.
“We initially focused on re-seeding native grass species but realized that we also need native forbs and shrubs in our re-seeding projects, particularly because these native species attract pollinators, native and non-native alike, and other insects that provide a crucial food source for birds, such as quail and grouse.
“Around 1998, Drs. Roger Sheley and Bruce Maxwell, at Montana State University, published a synthesis paper on successional weed management practices that framed integrated pest management in natural settings. The successional weed management concept transformed how we think about and approach weed management on rangelands and other natural settings. It is based on the three generally accepted drivers of secondary succession:
1 – site availability
2 – differential species availability, and
3 – differential species performance.
“As a result of this paper, many more Federal and State land management agencies became interested in weed management, as well as many more private landowners. We need diversity on the land. At any moment, certain plant species are being favored by the environment and other plant species are not. For example, some plants are more drought tolerant than others, while others thrive when precipitation is plentiful – both are needed by the plant community for it to thrive varying environmental conditions. Different plant species flower and set seed at different times of the year taking advantage of those conditions that favor them at particular times during the growing season. Different plant species provide forage for insects, birds, mammals, etc., at different times of the year. A successional system includes all these diverse elements.
“In successional weed management, you incorporate the following:
1 – designed disturbance to create available sites;
2 – controlled colonization to create diverse plant communities;
3 – controlled species performance to allow for diverse communities to thrive.
“An example I have used in my CSU classes is from my own land, an example on a small acreage: I bought a home that includes an old wheat field. It had lots of weeds initially. Here’s what I did on the land:
1 – I used Roundup (glyphosate) to kill field bindweed and all other plants on our property thereby creating many available sites for species to be seeded. And I used an aerator to pull plugs out of the field to help create sites that are more habitable than the soil surface. These two inputs were my designed disturbance.
2 – I broadcast seeded several species of native grass seed. This was my controlled colonization.
3 – I watered the seed, to aid establishment, which controlled species performance and allowed for all the seeded species to survive, producing well-developed root systems that promoted their ability to withstand the dry conditions that inevitably would return.
This process worked well on my small acreage.
“We need a variety of native grasses, forbs, and shrubs on rangeland. Some are more drought tolerant than others while other species take better advantage when soil moisture is increased by precipitation. Competition is the most important component of weed management – but it alone is not sufficient. For example, if I simply broadcast native seed across a field infested with Canada thistle, I get nothing. But if I treat the field with an appropriate herbicide, I’ll get a period of time with much decreased Canada thistle. That’s when I can plant the native grasses and forbs and improve their opportunity for successful establishment and keep Canada thistle from re-establishing when it recovers from the herbicide used to decrease its population or from other invading weeds.
“In my opinion, by using these techniques, we can diffuse most of the concerns about the use of herbicides or biocontrols, by minimizing how much of these tools we use. Once the native species are back and the system is intact, management input may not be needed.
“The US Congress loved the successional weed management approach.
“If we don’t manage invasive weeds, they will get worse. We cannot simply leave them alone.
“Within agriculture, we create monocultures, which makes weed management a different kind of problem. In rangeland, we do not create monocultures. We can create a diverse plant species community where species ebb and flow with the ever-changing environment (variable seasonal weather patterns being a good example) and plant community can be self-sustaining. In that diverse plant community, there always are a few species that thrive regardless of the ever-changing weather and growing conditions.
“In croplands, plant succession processes are always in the very early stages, where annual weed species thrive. Historically, farmers depended upon crop rotation to break weed cycles that are selected for in any given crop. While we once again using more crop rotation, for a period of time, we didn’t rotate crops much. With the advent of herbicides and then the eventual development of herbicide resistant crops, rotation diminished.
“Herbicides are very efficient, but very efficacious herbicides created new problems. Herbicides that kill 99% of a particular weed species or suite of species is a very intense selection pressure and ultimately finds those individuals within that species or suite of species in a particular field that are naturally resistant to that herbicide – they are the only survivors. We’re selecting for herbicide-resistant weeds now. For example, kochia is a very diverse species, and resistance to several herbicides has developed - use of particular herbicides selected for individuals that are resistant and those are the individuals that survived treatment. Herbicide-resistance is an international issue in the developed world. In the poorer nations where manual labor still is the primary mechanism to control weeds, herbicide resistance is not widespread. However, any weed control method is a selection pressure and individuals that are adapted to that method, will survive. This has even occurred in flooded rice production where weeds are hand-pulled, but that method selected for individuals of barnyardgrass, for example, that resemble the rice in which they are growing so, those individuals were not pulled and survived even hand-pulling. Hand-roguing weeds in a crop is a very intense selection pressure thus, it is not surprising, at least in retrospect, that selection for crop mimics occurs. Composition of DNA within a species is more diverse than was believed a few decades ago.
“Sulfonylurea herbicide resistance appeared within 3 years of using the herbicide chlorsulfuron (Glean) in Colorado wheat production. Growers were getting control of 98-99% of the kochia, but that quickly selected for resistant kochia individuals and within three years, control was at 0%.
“Not all herbicides readily select for resistance; 2-4,D rarely causes herbicide-resistance because it is not as effective as Glean and leaves behind susceptible individuals to 2,4-D, not just resistant individuals, so effective weed control persists. Glyphosate is another example of an intense selection pressure controlling 99% of target weed species, which quickly selects for those individuals that already exist in the environment and render the herbicide useless in that location. As those weeds continue to propagate and spread, as weeds surely do, soon large tracts of land are occupied by individuals within a species resistant to a particular herbicide.
“Selection for individuals within a species that are resistant to a particular weed control method is well-accepted today and part of our typical perspective. But mother nature, if you will, still has other surprises for land managers. At a Western Society of Weed Science meeting in 2013, one of the introductory session speakers reported some very interesting results of an experiment he carried out. He sprayed small plots for 6 consecutive years with glyphosate killing the vegetation present, all of which was weeds. Native species emerged after 6 years of this intense selection pressure that people had not observed in the locale for over 100 years. Weeds and other introduced species outcompeted native species, and those native species with a long soil seed bank emerged again after the competition was depleted. The designed disturbance of glyphosate spraying provided available space and interestingly, that space became occupied by native species that survived a century in a soil seed bank. Such an outcome provides faith that weed infested lands can be returned to a native plant community and this was an example of a very unusual circumstance that leaves one wondering how many more such circumstances await discovery!
“In many places where weeds have thrived for extended periods – especially if it is a monoculture of weeds such as cheatgrass in the western U.S. – all weeds can be killed, but nothing re-appears. In such areas where a naturally-occurring long-lived soil seed bank doesn’t exist, Dr. Roger Sheley theorized a potential solution - the seed island approach. In this approach, a small area is heavily seeded typically with native seed adapted to that area; a small percentage will survive, and these will spread over time. Such an approach is far less expensive than seeding an entire area, but cheatgrass alters soil environments making them inhospitable to other species, yet demonstrating another selection pressure that will only dissipate over time. Perhaps then, the seed island theory is an option that could work because its utility is only demonstrated over time.
“Returning to noxious or invasive weed legislative activity, Senator John Barrasso (Republican from Wyoming) and Tom Carper (Democrat from Delaware) co-sponsored the federal Wildlife Innovation and Longevity Driver (WILD) Act (S. 826). Part of the WILD Act contained S. 2240, which was the Senate version of H.R. 1485 the Federal Lands Invasive Species Control, Prevention, and Management Act introduced in the 114th Congress. The WILD Act passed the Senate on June 8, 2017 during the 115th Congress.
“The authors of the bill use the term Integrated Pest Management (IPM), rather than the term, ‘successional weed management,’ but it’s based on the same principle and IPM is more widely understood than successional weed management. The WILD Act focused on funds to infuse money into Africa to help save the African elephants and other African mammals. The invasive species sections are incorporated in the Act. The WILD Act would provide prize competitions for innovations to prevent poaching, the management of invasive species, and the protection of endangered species.
“Invasive species are huge problems in the western US. In Colorado now there is tremendous importance being placed on re-planting with native species. Almost all re-seeding now is with natives. Except, as previously noted, where the soil is so bad, so altered, that we might plant a non-native grass species that can be used for grazing yet, are competitive enough to resist weed invasion.
“Sage grouse habitat has become a serious concern in the west because the greater sage grouse populations are being considered to be listed as endangered by the U.S. Fish and Wildlife Service. The Federal government will spend a lot of money on re-establishing sagebrush habitat, which is the crucial for the sage grouse. Cheatgrass-fueled fires are one of the greater causes for sage brush demise and loss of sage grouse habitat. One aspect of the proposed federal policy on the greater sage grouse is to close all Federal roads in sagebrush areas. But in Colorado, only one county, Moffat County, has greater sage grouse, so this policy does not make sense.
“If we don’t have a healthy economy, we’re not going to entertain the idea of preserving our environment.
“Lewis Ziska, with the USDA-ARS, did research that showed that when carbon dioxide levels increase, as we are seeing occur now with climate change, C3 plants respond rapidly. In other words, the weeds, most of which possess C3 metabolism, grow faster and bigger as CO2 levels increase. Research by Dr. Harold Mooney, Stanford University, on yellow starthistle shows it absorbs more CO2 as those levels increase. Alaska has experienced few concerns about weeds in the past, but are now starting to see problems with knapweed and sweet clover. Increased atmospheric CO2 could be exacerbating this relatively new problem for Alaska.
“Colorado weed law states that native plant species cannot be designated as noxious weeds. Some farmers and ranchers wanted to add some native species to the noxious weed list. The Sierra Club, who helped get our bill passed, wanted only non-natives to be designated as noxious weeds and others working to pass the bill concurred. A local community can remove natives on local lands, but they cannot force their neighbors to do so on their lands.”
Dr. George Beck, Colorado State University Weed Scientist, interviewed in person by Dr. Delena Norris-Tull, October 24, 2017
Reviewed & approved April 11, 2021
Dr. Beck is now retired but still doing consulting work as Market Development Specialist for Alligare, LLC. Alligare is a post patent herbicide company out of Opelika, Alabama.
Dr. Beck was hired by Colorado State University in 1985 to work on perennial noxious weed issues on rangeland and in pastures. He served on ISAC (Invasive Species Advisory Committee) from 2002-2008 and was chairman for 2 years. In our 1.5 hour interview, he provided me with a brief history of weed legislation at the state and federal levels.
“Currently, about 40 states have Noxious Weeds laws. Every state has a noxious weed seed list.
“At the federal level, the focus is on ‘weeds.’ I served on the Intermountain Noxious Weed Advisory Council (INWAC) and the Healthy Habitats Coalition (HHC) and both groups were trying to improve weed management by the federal government. The federal land management agencies are the biggest problem for weed management because they manage so much land, and weed management has become very political.
“In 1985, I helped with a workshop in Denver to a group of representatives from Federal agencies. Back then, the Colorado weed law was bizarre, but at least we had legislation related to weed management. At that time, some of the Federal representatives, particularly the representatives from the BLM (US Bureau of Land Management) were very arrogant towards us at the state level. One individual said, ‘You cannot tell us what to do, we work for the federal government.’
“Wyoming has had an excellent history working with weed management. INWAC was started by the then Wyoming Weed and Pest Coordinator, George Hittle. INWAC knew an improved federal weed law was needed. We helped write what is still known as Section 2814 (7 U.S.C 2814), the Federal Noxious Weed Act of 1974 (FNWA). In this law, it stated that the Federal agencies must work with the State and local agencies to manage noxious weeds. In other words, the law made it clear that the Federal agencies are not in charge of what we do at the State level and they must collaborate with us.
“The FNWA was repealed in 2000. APHIS (Animal and Plant Health Inspection Service) was already working on the Federal Plant Protection Act that replaced several laws including the Federal Noxious Weed Act of 1974. Section 2814 was the only section saved from the FNWA that was directly incorporated into the newly proposed law.”
“A Congressional bill, H.R. 1485 the Federal Lands Invasive Species Control, Prevention, and Management Act, is currently sitting in the US House of Representatives, waiting for the Senate to write a companion bill. This bill expanded on weeds to include all invasive taxa and would require federal land management agencies to develop invasive species management programs. Spending parameters were outlined that required the Departments of Agriculture and Interior to spend no less than 75% of identified invasive species management funds on the ground to directly control the problems, no more than 15% of those funds could be spent on outreach and discovery, and no more than 10% of the funds be spent on administration.
“About 15 years ago, the National Park Service developed a team concept to facilitate coordinated weed management among the National Parks. For example, there was a team that included Carlsbad National Park, Lake Mead National Recreation Area, and Rocky Mountain National Park. These teams remain active to this day and are called ‘Exotic Plant Management Teams.’ Department of Interior NPS officials provide funds for weed management projects within individual national parks that otherwise do not have direct funds to support – the funding comes out of Washington DC and not the individual parks. This approach has been very successful for NPS but the problem outstrips the capacity to resolve the issue.
“There is a tongue-in-cheek estimate that only about 50% of the people in any Federal land management agency actually do the weed management work. Unfortunately, those not doing the work are often the nay-sayers that can influence the development of appropriate policies that could resolve the problem.
“The term ‘Noxious’ has its founding in agriculture; people long ago recognized certain plants that grew in association with the farming efforts were key problems. Rangeland, however, is dealt with differently than arable lands. Rangeland is expected to have minimal inputs. In other words, there is little money available for improving rangeland and there are little funds made available for managing weeds on rangeland.
“Over the years, we have managed to gain enough attention to weed management concerns, that people at the State and Federal levels and those holding private properties started to listen to our concerns about weed management on rangeland. Additionally, wildlife areas, open space and similar descriptors were adopted to recognize those lands where State and Federal land management agencies were the administrators, or managers, to distinguish from the traditional definition of ‘rangeland’ and thus, make providing for invasive species management funds for such real estate doable in the minds of many decision makers.
“In the 1980s and 1990s, our focus broadened from just using herbicides to control weeds to developing integrated weed management systems – i.e., what changed over the years is how we describe what we are doing and implementing those plans. We learned that when we explained that we’re trying to improve the productivity of rangeland, open space, and wildlife habitat, that’s when people began to listen.”
Cheatgrass concerns: “When we started controlling cheatgrass (with herbicides) in areas where it was beginning to invade, we started seeing native plant species coming back. But on severely abused lands, where cheatgrass had dominated for years, that doesn’t happen. We learned that in those cases, we have to re-seed the rangeland, open space, and wildlife areas with native species to return those areas to productivity.
“We are beginning to learn how invasive weeds alter the soil and subsequently, the native plant communities and how these impacts can be ameliorated. Temporary use of herbicides and other tools to decrease weeds in severely invaded lands, have minimal impact compared to the effects of invasive weeds on the soil systems. But even old stands of invasive weeds can be recovered, but take greater time and effort. The key to success is beginning reclamation and restoration efforts where the native plant community still has a presence, as those areas are easier to recover and cost less money and time to do so.
“In the 1980s, the federal government initiated the Conservation Reserve Program (CRP). This program was an outgrowth of the old farming approach on marginally productive lands that helped create the Dust Bowl. The CRP program provides subsidies to private landowners to take marginal farm land out of production, turn that land back into grasslands. These lands cannot be grazed or farmed and are put back into prairies. If this program had not been initiated, our current concepts of weed management may not have been readily adopted.
“The US Natural Resources Conservation Service (NRCS; formerly the US Soil Conservation Service) demonstrated through the CRP program that native plants will endure longer than non-natives, as native plant communities are better adapted to the grassland/prairie landscapes that formerly dominated much of the central U.S. Marginal farm lands on the Great Plains are better suited to be prairies where, someday, well-managed grazing by livestock and wildlife still will allow for agricultural production.
“In Colorado, we have state-level Conservation Districts. These are the longest-standing fighters of weeds in our state. They are the local connections to the NRCS and the USDA and allow for local input into changes in land management practices.
“We initially focused on re-seeding native grass species but realized that we also need native forbs and shrubs in our re-seeding projects, particularly because these native species attract pollinators, native and non-native alike, and other insects that provide a crucial food source for birds, such as quail and grouse.
“Around 1998, Drs. Roger Sheley and Bruce Maxwell, at Montana State University, published a synthesis paper on successional weed management practices that framed integrated pest management in natural settings. The successional weed management concept transformed how we think about and approach weed management on rangelands and other natural settings. It is based on the three generally accepted drivers of secondary succession:
1 – site availability
2 – differential species availability, and
3 – differential species performance.
“As a result of this paper, many more Federal and State land management agencies became interested in weed management, as well as many more private landowners. We need diversity on the land. At any moment, certain plant species are being favored by the environment and other plant species are not. For example, some plants are more drought tolerant than others, while others thrive when precipitation is plentiful – both are needed by the plant community for it to thrive varying environmental conditions. Different plant species flower and set seed at different times of the year taking advantage of those conditions that favor them at particular times during the growing season. Different plant species provide forage for insects, birds, mammals, etc., at different times of the year. A successional system includes all these diverse elements.
“In successional weed management, you incorporate the following:
1 – designed disturbance to create available sites;
2 – controlled colonization to create diverse plant communities;
3 – controlled species performance to allow for diverse communities to thrive.
“An example I have used in my CSU classes is from my own land, an example on a small acreage: I bought a home that includes an old wheat field. It had lots of weeds initially. Here’s what I did on the land:
1 – I used Roundup (glyphosate) to kill field bindweed and all other plants on our property thereby creating many available sites for species to be seeded. And I used an aerator to pull plugs out of the field to help create sites that are more habitable than the soil surface. These two inputs were my designed disturbance.
2 – I broadcast seeded several species of native grass seed. This was my controlled colonization.
3 – I watered the seed, to aid establishment, which controlled species performance and allowed for all the seeded species to survive, producing well-developed root systems that promoted their ability to withstand the dry conditions that inevitably would return.
This process worked well on my small acreage.
“We need a variety of native grasses, forbs, and shrubs on rangeland. Some are more drought tolerant than others while other species take better advantage when soil moisture is increased by precipitation. Competition is the most important component of weed management – but it alone is not sufficient. For example, if I simply broadcast native seed across a field infested with Canada thistle, I get nothing. But if I treat the field with an appropriate herbicide, I’ll get a period of time with much decreased Canada thistle. That’s when I can plant the native grasses and forbs and improve their opportunity for successful establishment and keep Canada thistle from re-establishing when it recovers from the herbicide used to decrease its population or from other invading weeds.
“In my opinion, by using these techniques, we can diffuse most of the concerns about the use of herbicides or biocontrols, by minimizing how much of these tools we use. Once the native species are back and the system is intact, management input may not be needed.
“The US Congress loved the successional weed management approach.
“If we don’t manage invasive weeds, they will get worse. We cannot simply leave them alone.
“Within agriculture, we create monocultures, which makes weed management a different kind of problem. In rangeland, we do not create monocultures. We can create a diverse plant species community where species ebb and flow with the ever-changing environment (variable seasonal weather patterns being a good example) and plant community can be self-sustaining. In that diverse plant community, there always are a few species that thrive regardless of the ever-changing weather and growing conditions.
“In croplands, plant succession processes are always in the very early stages, where annual weed species thrive. Historically, farmers depended upon crop rotation to break weed cycles that are selected for in any given crop. While we once again using more crop rotation, for a period of time, we didn’t rotate crops much. With the advent of herbicides and then the eventual development of herbicide resistant crops, rotation diminished.
“Herbicides are very efficient, but very efficacious herbicides created new problems. Herbicides that kill 99% of a particular weed species or suite of species is a very intense selection pressure and ultimately finds those individuals within that species or suite of species in a particular field that are naturally resistant to that herbicide – they are the only survivors. We’re selecting for herbicide-resistant weeds now. For example, kochia is a very diverse species, and resistance to several herbicides has developed - use of particular herbicides selected for individuals that are resistant and those are the individuals that survived treatment. Herbicide-resistance is an international issue in the developed world. In the poorer nations where manual labor still is the primary mechanism to control weeds, herbicide resistance is not widespread. However, any weed control method is a selection pressure and individuals that are adapted to that method, will survive. This has even occurred in flooded rice production where weeds are hand-pulled, but that method selected for individuals of barnyardgrass, for example, that resemble the rice in which they are growing so, those individuals were not pulled and survived even hand-pulling. Hand-roguing weeds in a crop is a very intense selection pressure thus, it is not surprising, at least in retrospect, that selection for crop mimics occurs. Composition of DNA within a species is more diverse than was believed a few decades ago.
“Sulfonylurea herbicide resistance appeared within 3 years of using the herbicide chlorsulfuron (Glean) in Colorado wheat production. Growers were getting control of 98-99% of the kochia, but that quickly selected for resistant kochia individuals and within three years, control was at 0%.
“Not all herbicides readily select for resistance; 2-4,D rarely causes herbicide-resistance because it is not as effective as Glean and leaves behind susceptible individuals to 2,4-D, not just resistant individuals, so effective weed control persists. Glyphosate is another example of an intense selection pressure controlling 99% of target weed species, which quickly selects for those individuals that already exist in the environment and render the herbicide useless in that location. As those weeds continue to propagate and spread, as weeds surely do, soon large tracts of land are occupied by individuals within a species resistant to a particular herbicide.
“Selection for individuals within a species that are resistant to a particular weed control method is well-accepted today and part of our typical perspective. But mother nature, if you will, still has other surprises for land managers. At a Western Society of Weed Science meeting in 2013, one of the introductory session speakers reported some very interesting results of an experiment he carried out. He sprayed small plots for 6 consecutive years with glyphosate killing the vegetation present, all of which was weeds. Native species emerged after 6 years of this intense selection pressure that people had not observed in the locale for over 100 years. Weeds and other introduced species outcompeted native species, and those native species with a long soil seed bank emerged again after the competition was depleted. The designed disturbance of glyphosate spraying provided available space and interestingly, that space became occupied by native species that survived a century in a soil seed bank. Such an outcome provides faith that weed infested lands can be returned to a native plant community and this was an example of a very unusual circumstance that leaves one wondering how many more such circumstances await discovery!
“In many places where weeds have thrived for extended periods – especially if it is a monoculture of weeds such as cheatgrass in the western U.S. – all weeds can be killed, but nothing re-appears. In such areas where a naturally-occurring long-lived soil seed bank doesn’t exist, Dr. Roger Sheley theorized a potential solution - the seed island approach. In this approach, a small area is heavily seeded typically with native seed adapted to that area; a small percentage will survive, and these will spread over time. Such an approach is far less expensive than seeding an entire area, but cheatgrass alters soil environments making them inhospitable to other species, yet demonstrating another selection pressure that will only dissipate over time. Perhaps then, the seed island theory is an option that could work because its utility is only demonstrated over time.
“Returning to noxious or invasive weed legislative activity, Senator John Barrasso (Republican from Wyoming) and Tom Carper (Democrat from Delaware) co-sponsored the federal Wildlife Innovation and Longevity Driver (WILD) Act (S. 826). Part of the WILD Act contained S. 2240, which was the Senate version of H.R. 1485 the Federal Lands Invasive Species Control, Prevention, and Management Act introduced in the 114th Congress. The WILD Act passed the Senate on June 8, 2017 during the 115th Congress.
“The authors of the bill use the term Integrated Pest Management (IPM), rather than the term, ‘successional weed management,’ but it’s based on the same principle and IPM is more widely understood than successional weed management. The WILD Act focused on funds to infuse money into Africa to help save the African elephants and other African mammals. The invasive species sections are incorporated in the Act. The WILD Act would provide prize competitions for innovations to prevent poaching, the management of invasive species, and the protection of endangered species.
“Invasive species are huge problems in the western US. In Colorado now there is tremendous importance being placed on re-planting with native species. Almost all re-seeding now is with natives. Except, as previously noted, where the soil is so bad, so altered, that we might plant a non-native grass species that can be used for grazing yet, are competitive enough to resist weed invasion.
“Sage grouse habitat has become a serious concern in the west because the greater sage grouse populations are being considered to be listed as endangered by the U.S. Fish and Wildlife Service. The Federal government will spend a lot of money on re-establishing sagebrush habitat, which is the crucial for the sage grouse. Cheatgrass-fueled fires are one of the greater causes for sage brush demise and loss of sage grouse habitat. One aspect of the proposed federal policy on the greater sage grouse is to close all Federal roads in sagebrush areas. But in Colorado, only one county, Moffat County, has greater sage grouse, so this policy does not make sense.
“If we don’t have a healthy economy, we’re not going to entertain the idea of preserving our environment.
“Lewis Ziska, with the USDA-ARS, did research that showed that when carbon dioxide levels increase, as we are seeing occur now with climate change, C3 plants respond rapidly. In other words, the weeds, most of which possess C3 metabolism, grow faster and bigger as CO2 levels increase. Research by Dr. Harold Mooney, Stanford University, on yellow starthistle shows it absorbs more CO2 as those levels increase. Alaska has experienced few concerns about weeds in the past, but are now starting to see problems with knapweed and sweet clover. Increased atmospheric CO2 could be exacerbating this relatively new problem for Alaska.
“Colorado weed law states that native plant species cannot be designated as noxious weeds. Some farmers and ranchers wanted to add some native species to the noxious weed list. The Sierra Club, who helped get our bill passed, wanted only non-natives to be designated as noxious weeds and others working to pass the bill concurred. A local community can remove natives on local lands, but they cannot force their neighbors to do so on their lands.”