Genetically Engineered Grass: The Roundup Ready Bentgrass Escape, Scotts’ GM Bluegrass, and What It Means

Most genetically engineered crops are annual food and feed crops such as corn and soybeans, planted each year in fields. In the early 2000s, Scotts Miracle-Gro and Monsanto set out to engineer something different: a perennial lawn and golf course grass that could survive spraying with Roundup, so that golf course managers and homeowners could kill weeds without harming turf. Field trials of the engineered creeping bentgrass went forward, and opponents warned that a wind-pollinated, perennial grass would be nearly impossible to contain.

They were right about containment. The engineered grass escaped test fields in Oregon, crossed with wild relatives, and still grows along irrigation ditches more than two decades later. Scotts paid a federal penalty, abandoned commercialization, and the U.S. Department of Agriculture ultimately deregulated the grass in 2017. Meanwhile, a different Scotts genetically engineered Kentucky bluegrass bypassed federal review altogether. This article explains what happened, what scientists learned about gene flow, and what it means for regulation and for homeowners.

Why Engineer a Grass?

Creeping bentgrass is prized for golf course greens and tees because it tolerates very close mowing and forms a dense, smooth surface. Weeds and other grasses that invade greens are hard to control without harming the bentgrass itself. Scotts and Monsanto began developing a Roundup Ready version in the 1990s, inserting the CP4 EPSPS gene from a bacterium, the same trait used in Roundup Ready soybeans and corn, so that golf course superintendents could spray glyphosate to kill unwanted plants while leaving the engineered bentgrass unharmed. If successful, the trait could also have been extended to home lawns.

Grasses pose special challenges for containment compared with crops such as soybeans. Creeping bentgrass is perennial, so plants can persist for years; it spreads by both seeds and creeping stems called stolons; it is wind-pollinated, so pollen can travel long distances; and it is highly outcrossing and can hybridize with related wild and weedy grass species. Weed scientists had warned that these traits made it one of the riskiest candidates for genetic engineering.

The Oregon Escape

In 2002 and 2003, Scotts grew engineered bentgrass for seed production on about 400 acres in a designated control area near Madras in central Oregon. A 2004 study in the Proceedings of the National Academy of Sciences by Lidia Watrud and colleagues at the U.S. Environmental Protection Agency placed sentinel bentgrass plants and sampled resident wild grasses around the fields. Using glyphosate resistance as a marker, they found gene flow to 75 of 138 sentinel plants and 29 of 69 resident plants. Most gene flow occurred within 2 kilometers in the direction of prevailing winds, but the maximum distances were 21 kilometers for sentinel plants and 14 kilometers for resident plants, mostly in non-agricultural habitats. The study was the first to document landscape-level gene flow from a GM crop in the United States.

In August 2003, winds also scattered seed during harvest, spreading the grass beyond the fields. A 2006 follow-up in Molecular Ecology by Jay Reichman and colleagues reported the first evidence that transgenes had escaped into wild plant populations in the United States: among 20,400 samples of three compatible bentgrass species in non-agricultural habitats outside the control area, nine creeping bentgrass plants carried the glyphosate-resistance transgene, located mostly along waterways. The authors noted that transgenic plants had established beyond the production fields.

Engineered bentgrass also appeared in eastern Oregon near the Idaho border, where Scotts had grown seed in Canyon County, Idaho, and in Malheur County, Oregon, before destroying the fields in the mid-2000s. Colorado State University Extension noted that populations of glyphosate-resistant bentgrass were still being discovered in eastern Oregon as recently as 2010. High Country News reported in 2018 that the grass continued to grow along irrigation ditches near Ontario, Oregon, where farmers and irrigation districts struggled to control it, and that its pollen had fertilized conventional bentgrass as far as 13 miles away.

Crossing Into Another Genus

The escape revealed another risk: hybridization with related species. A 2012 study in Molecular Ecology by Maria Zapiola and Carol Mallory-Smith of Oregon State University reported that a feral transgenic creeping bentgrass plant had produced a hybrid with rabbitfoot grass (Polypogon monspeliensis), a species in a different genus, through spontaneous pollination in the field. The hybrid carried the glyphosate-resistance transgene. Intergeneric hybrids in nature are unusual, and the finding showed that transgenes from engineered grasses could move into related weedy species, potentially creating glyphosate-resistant weeds that are harder to control.

Penalty, Eradication Efforts, and Deregulation

According to reporting republished by The Ecologist, the USDA fined Scotts $500,000 in 2007 for allowing the escape and held the company responsible for controlling and eradicating the engineered grass. Scotts worked for years to find and kill escaped plants, including along irrigation canals and ditches in Jefferson and Malheur counties, but eradication proved impossible, and the company eventually announced it would not commercialize the product. Scotts nonetheless asked the USDA to deregulate the grass, which would end federal oversight and the company’s obligation to control it.

The USDA granted deregulation on January 17, 2017. Environmental groups, including the Center for Food Safety and the Center for Biological Diversity, criticized the decision, arguing it shifted the burden of controlling an unwanted engineered grass onto Oregon and Idaho farmers, irrigation districts, and public land managers. After deregulation, long-term control effectively rests with local landowners, irrigation districts, and public land managers. Oregon grass seed growers worried about export markets, since many international buyers prize Oregon seed for being free of genetically engineered traits.

The Kentucky Bluegrass That Skipped Federal Review

While the bentgrass saga unfolded, Scotts developed a glyphosate-tolerant Kentucky bluegrass, the most popular lawn grass in much of the northern United States, using a different approach. Scotts designed the new grass to avoid genetic elements from plant pests, such as the bacterial sequences commonly used to insert and express traits in earlier engineered crops. Colorado State University Extension explains that in 2011 the USDA ruled it would not regulate the development or release of the glyphosate-resistant Kentucky bluegrass, paving the way for testing in some Scotts employees’ yards in 2014 and limited commercialization in 2015. The ruling exposed a gap: U.S. regulations for engineered plants at the time focused on whether a plant was or could become a plant pest, so engineered plants made without plant pest sequences could escape review entirely.

The USDA later revised its biotechnology regulations, adopting a rule in 2020 that exempted many engineered plants from regulation based on the type of modification, a framework later challenged in court. Critics argued the changes further weakened oversight, while supporters said they focused regulation on genuine risks and would encourage innovation, particularly in gene editing. The regulatory landscape for engineered lawn grasses remains less stringent than many consumers assume.

Glyphosate-Resistant Weeds: The Bigger Picture

The bentgrass story is part of a broader problem: heavy reliance on glyphosate has driven the evolution of resistant weeds. A 2018 review in Pest Management Science by Ian Heap and Stephen Duke reported that 38 weed species had evolved glyphosate resistance in 37 countries, first appearing in Australia in 1996, the same year glyphosate-resistant soybeans were introduced in the United States. Resistance has spread most in glyphosate-tolerant crop systems, where the herbicide is used repeatedly. Engineered turfgrass would have encouraged similar reliance on a single herbicide in lawns and golf courses, and escaped transgenic grasses add another route for resistance to spread among weedy relatives.

Feature	GM creeping bentgrass	GM Kentucky bluegrass
Developers	Scotts and Monsanto	Scotts
Intended use	Golf course greens and tees	Home lawns
Trait	Glyphosate resistance (CP4 EPSPS)	Glyphosate tolerance
Federal review	Regulated; deregulated 2017	Not regulated (2011 ruling)
Outcome	Escaped; not commercialized	Tested and limited release reported

Problems for Farmers and Irrigation Districts

In eastern Oregon, escaped engineered bentgrass has grown in irrigation canals and ditches, where it can slow water flow and must be controlled. Because the grass resists glyphosate, the most common and inexpensive herbicide used to manage ditch-bank vegetation, managers must use other herbicides, mechanical removal, or burning, which increase costs. Farmers have expressed concern about the grass spreading into hay fields and seed crops. Scotts paid for control work during the period of federal regulation, but after deregulation, local landowners and districts bear more of the burden. The experience illustrates how an escaped engineered trait can impose costs on people who never chose to use it.

Oregon’s Grass Seed Industry

Oregon’s Willamette Valley is often described as the grass seed capital of the world, producing a large share of the cool-season grass seed used for lawns, pastures, and turf in the United States and abroad. Many international buyers, particularly in Europe and Asia, require seed free of genetically engineered traits. Growers feared that engineered bentgrass contamination could jeopardize these markets, and the state has considered measures to protect seed purity, including control areas and testing. Contamination incidents in other crops, such as unapproved engineered wheat found in an Oregon field in 2013, which temporarily disrupted wheat exports to Japan and Korea, reinforced these concerns.

Lessons for Regulating Engineered Plants

Scientists and policy analysts draw several lessons from the bentgrass case. Perennial, wind-pollinated, outcrossing plants with wild relatives pose much greater containment challenges than annual crops, and field trials of such plants require stronger safeguards. Once an engineered trait escapes into wild populations, eradication may be impossible. Regulators need clear authority over the full range of engineered plants, not only those containing plant pest sequences, and clear rules on who bears responsibility for escapes. Post-release monitoring and public reporting help communities respond. These lessons apply equally to new gene-edited plants, some of which may face less oversight under recent regulatory changes.

What Homeowners Should Know

Most grass seed sold to homeowners is conventionally bred, not genetically engineered, and there is no federal requirement to label engineered grass seed. Homeowners concerned about engineered varieties can ask seed suppliers, choose seed certified by state seed certification programs, or buy from companies that state their products are non-GMO. More importantly, a lawn designed around frequent glyphosate spraying would increase herbicide use around homes. Healthy lawn practices, such as choosing grass suited to local conditions, mowing high, aerating, overseeding, and spot treating weeds, reduce the need for herbicides regardless of grass type. Our article on Scotts lawn chemicals and children’s and pets’ exposure covers these practices in more detail.

Ecological Concerns

Beyond agriculture, ecologists worry about effects on natural areas. The Crooked River National Grassland near Madras, where seeds blew during the 2003 harvest, is federal public land managed for native vegetation and wildlife. Creeping bentgrass is not native to the region and can compete with native plants along streams and wetlands. Land managers often use glyphosate to control invasive plants in sensitive habitats because it breaks down relatively quickly and has low toxicity to wildlife compared with some alternatives. Glyphosate-resistant bentgrass removes this tool, forcing managers to use other methods. Fish and wildlife officials raised concerns about potential impacts on habitat for threatened species if engineered bentgrass spread more widely.

The Golf Industry’s Perspective

Golf course superintendents were the intended market for Roundup Ready bentgrass, and some saw value in simpler weed control on greens, where invasive annual bluegrass is a persistent problem. Others worried about relying on a single herbicide and about public perception of genetically engineered turf. Turfgrass breeders have continued developing improved conventional varieties with better disease resistance, heat tolerance, and lower water and fertilizer needs, offering ways to reduce chemical inputs without genetic engineering. Many golf courses now adopt integrated pest management and environmental stewardship programs, reflecting broader interest in sustainable turf management.

Gene Editing and the Future of Turfgrass

New gene-editing tools such as CRISPR allow targeted changes to plant DNA without necessarily inserting foreign genes. Researchers are exploring edits to turfgrass for drought tolerance, slower growth to reduce mowing, and disease resistance. Under recent U.S. regulatory approaches, some gene-edited plants may not require the same review as earlier engineered crops, depending on the type of change. Supporters argue gene editing could produce lawns that need less water, fertilizer, and pesticide. Critics warn that the bentgrass experience shows the importance of evaluating gene flow and ecological effects for perennial, wind-pollinated grasses, regardless of the technique used. Transparent review and monitoring could help avoid repeating past mistakes.

Why Containment Is So Hard for Grasses

Containing an engineered trait requires preventing the spread of pollen, seed, and plant fragments. Creeping bentgrass makes all three difficult. Its tiny pollen grains travel on the wind for kilometers. Its seeds are extremely small and can be carried by wind, water, birds, equipment, and vehicles. Its stolons root wherever they touch moist soil, allowing fragments moved by water or machinery to establish new plants. The grass is also long-lived and can survive in irrigation ditches, roadsides, and wetlands where it is rarely noticed. Effective containment would have required isolation distances and monitoring far beyond what was used in the field trials, and once plants established in the wild, finding every individual among similar-looking grasses was nearly impossible.

Herbicide-Tolerant Crops and Herbicide Use

Herbicide-tolerant crops were designed to simplify weed control, but they have also changed herbicide use patterns. Glyphosate use rose dramatically after the introduction of glyphosate-tolerant crops in the 1990s, and the resulting selection pressure contributed to resistant weeds. Farmers responded by adding older herbicides such as dicamba and 2,4-D, and companies developed crops tolerant to multiple herbicides. Applying the same model to lawns and golf courses would have encouraged routine broadcast glyphosate spraying in residential and recreational areas where people and pets spend time. This is one reason many homeowners and environmental groups opposed engineered turf even apart from the escape.

How Other Countries Regulate Engineered Plants

Regulatory approaches differ worldwide. The European Union requires authorization of each genetically modified organism for cultivation, with environmental risk assessment, traceability, and labeling, and member states can restrict cultivation. Few engineered crops are grown commercially in Europe. Canada regulates plants with novel traits regardless of how they were produced, focusing on the trait rather than the method. These approaches contrast with U.S. rules, which have historically focused on plant pest risk and have recently exempted many modifications. International differences affect seed exports, research, and the commercial prospects of engineered turfgrass.

A Balanced View

Genetic engineering has produced useful crops, and not every engineered plant poses the containment challenges of creeping bentgrass. But the bentgrass case shows that some plants are poor candidates for engineered traits that can spread, and that regulators and companies underestimated the difficulty of containment. The escaped grass has not caused a catastrophe, but it imposes ongoing costs on people who never chose it. Thoughtful regulation that considers each plant’s biology, holds developers responsible for escapes, and monitors released traits serves both innovation and the public interest.

Practical Takeaways

Homeowners do not need engineered grass for a healthy lawn. Choose grass species and varieties suited to your climate, follow low-input lawn practices, and use spot treatments rather than broadcast herbicides. Ask seed suppliers about their products if you want to avoid engineered varieties. Support policies that ensure transparent review of engineered plants, especially perennial and wind-pollinated species, and that hold developers accountable for unintended spread.

How Escaped Plants Are Detected

Finding engineered bentgrass among ordinary grasses requires testing, since the plants look identical. Field crews have used two main methods: spraying suspect areas with glyphosate and checking which bentgrass plants survive, and using rapid test strips that detect the CP4 EPSPS protein in leaf samples, followed by laboratory confirmation. Researchers in the EPA studies also grew seedlings from collected seed and sprayed them with glyphosate to detect gene flow through pollen. These methods are labor-intensive, which is one reason surveillance and eradication over large areas proved so difficult and costly.

Public Lands and Federal Agencies

Because engineered bentgrass spread onto public lands, including the Crooked River National Grassland managed by the U.S. Forest Service, federal land agencies have had to consider it in vegetation management. The U.S. Fish and Wildlife Service raised concerns during the deregulation review about potential effects on habitat for threatened and endangered species, such as plants and fish associated with streams and wetlands, if the grass spread into sensitive areas. These concerns highlighted a tension between agricultural biotechnology regulation, administered by the USDA, and the responsibilities of agencies charged with protecting public lands and wildlife.

Monsanto’s Role and Bayer

Monsanto partnered with Scotts in developing the engineered bentgrass, supplying the glyphosate-resistance technology used in its Roundup Ready crops. Bayer acquired Monsanto in 2018, after the bentgrass had been deregulated and commercialization abandoned. The partnership between Scotts and Monsanto also extended to Scotts’ role marketing consumer Roundup products, a relationship that continued with Bayer. The bentgrass episode remains one of the most cited examples in debates over the environmental risks of genetically engineered plants.

Further Reading

The peer-reviewed studies cited here document gene flow, establishment in wild habitats, and intergeneric hybridization of engineered bentgrass. Investigative reporting by High Country News and other outlets describes the ongoing situation in eastern Oregon. University extension services provide guidance on low-input lawn care and on herbicide-tolerant turf.

Questions Communities Can Ask

Communities near field trials of engineered plants can ask regulators and developers several questions. What containment measures are planned, and how far can pollen and seed travel for this species? Are there wild or weedy relatives nearby that could hybridize? Who will monitor for escapes, for how long, and with what public reporting? Who pays for control if the trait escapes? What happens if the developer abandons the product? Clear answers before trials begin can prevent situations like Oregon’s, where local landowners inherited a problem they did not create.

Why This Story Still Matters

More than twenty years after the first escape, the engineered bentgrass remains a living reminder that releasing self-reproducing organisms is different from releasing chemicals, which eventually break down. Once a trait is established in wild populations, it can persist indefinitely and spread in ways that are hard to predict. As new technologies make it easier to modify plants and other organisms, including gene drives designed to spread through wild populations, the lessons of the bentgrass case remain relevant to decisions about what to release, where, and with what safeguards.

Choosing Grass Seed Wisely

When buying grass seed, look at the label, which lists species, varieties, germination rates, and weed seed content. Blends of species suited to your region, such as fine fescues for shade or tall fescue for drought tolerance, produce resilient lawns that need fewer inputs. Certified seed from state programs meets standards for purity. Local extension offices can recommend varieties that perform well in your area with minimal water, fertilizer, and herbicide.

Common Myths

“GM grass is widely sold for lawns.” Engineered creeping bentgrass was never commercialized, and engineered bluegrass has had only limited release; most lawn seed is conventional.

“The escaped grass caused an ecological catastrophe.” It persists and imposes control costs, but has not caused the widespread disaster some predicted.

“Escaped transgenes stay within the same species.” The engineered trait crossed into rabbitfoot grass, a different genus.

“All engineered plants go through federal review.” The 2011 bluegrass ruling showed some engineered plants escaped review.

“Deregulation means the grass was eradicated.” Deregulation ended federal oversight while the grass continued to grow in Oregon.

Key Terms

Creeping bentgrass: A fine-textured grass used on golf greens, Agrostis stolonifera.

Gene flow: Movement of genes between populations through pollen or seed.

CP4 EPSPS: A bacterial gene that confers glyphosate resistance, used in Roundup Ready crops.

Deregulation: A USDA decision that ends federal oversight of an engineered organism.

Intergeneric hybrid: A cross between plants from different genera.

The Bottom Line

The effort by Scotts and Monsanto to create Roundup Ready grass became a cautionary tale about engineering perennial, wind-pollinated plants. Pollen and seed escaped test fields in Oregon, the transgene spread to wild bentgrass and even to a different genus, and more than two decades later the grass persists in irrigation ditches despite years of control efforts and a $500,000 federal penalty. The USDA deregulated the grass in 2017, shifting long-term control to local communities, while a separate engineered bluegrass escaped federal review on a technicality. For homeowners, the main takeaway is that lawns do not need herbicide-tolerant grass; healthy turf practices and spot treatments keep weeds manageable with far less chemical use.

Frequently Asked Questions

Is genetically modified grass sold in stores?

Engineered creeping bentgrass was never commercialized. Glyphosate-tolerant Kentucky bluegrass had limited testing and release; most grass seed is conventional.

What happened to the escaped GM grass?

It still grows in parts of central and eastern Oregon, especially along irrigation ditches, and resists glyphosate.

Was Scotts penalized?

Yes. The USDA fined Scotts $500,000 in 2007 and required control efforts until the grass was deregulated in 2017.

Can engineered grass genes spread to other plants?

Yes. Studies documented gene flow up to 21 kilometers and a hybrid with rabbitfoot grass.

How can I keep a lawn weed-free without Roundup?

Choose suitable grass, mow high, water deeply but infrequently, aerate, overseed, and spot treat or hand-pull weeds.

References

1. Watrud LS, Lee EH, Fairbrother A, et al. Evidence for landscape-level, pollen-mediated gene flow from genetically modified creeping bentgrass with CP4 EPSPS as a marker. Proceedings of the National Academy of Sciences of the USA. 2004;101(40):14533–14538. PMID 15448206
2. Reichman JR, Watrud LS, Lee EH, et al. Establishment of transgenic herbicide-resistant creeping bentgrass (Agrostis stolonifera L.) in nonagronomic habitats. Molecular Ecology. 2006;15(13):4243–4255. PMID 17054516
3. Zapiola ML, Mallory-Smith CA. Crossing the divide: gene flow produces intergeneric hybrid in feral transgenic creeping bentgrass population. Molecular Ecology. 2012;21(19):4672–4680. PMID 22625177
4. Heap I, Duke SO. Overview of glyphosate-resistant weeds worldwide. Pest Management Science. 2018;74(5):1040–1049. PMID 29024306
5. High Country News. Genetically modified grass creeps across eastern Oregon. 2018. hcn.org
6. Colorado State University Extension, PlantTalk. The Truth About Roundup-Resistant Turf. planttalk.colostate.edu
7. The Ecologist. Escaped GMO ‘Triffid grass’ defies eradication. January 2017. theecologist.org
8. Missouri Invasive Plant Council. Decision to deregulate creeping bentgrass. January 2017. moinvasives.org

Last updated: October 6, 2026