Dicamba Drift: The Herbicide System That Divided Farm Country, Two Court Reversals, and EPA’s 2026 Re-Approval

When Bayer completed its acquisition of Monsanto in 2018, headlines predicted the combined company would launch the biggest agricultural biotechnology research effort in history. One of the most consequential products the two companies brought together was a crop system built around dicamba, an old herbicide paired with new genetically engineered soybeans and cotton that tolerate it. Within a few years, dicamba had become one of the most contentious chemicals in American agriculture, damaging millions of acres of neighboring crops, dividing farm communities, prompting lawsuits, and being thrown out by federal courts twice.

In February 2026, the EPA approved over-the-top dicamba use again, with what it called the strongest restrictions in its history. This article explains what dicamba is, why it drifts, what the courts decided, what the new rules require, and what is at stake for farmers, neighbors, and the environment.

What Dicamba Is and Why It Came Back

Dicamba is a synthetic auxin herbicide, a type of chemical that mimics plant growth hormones and causes susceptible broadleaf plants to grow abnormally and die. It has been used since the 1960s, mainly on corn, small grains, and pastures, and before crops emerge. Soybeans and many other broadleaf crops are extremely sensitive to it; tiny amounts can cause characteristic cupped, puckered leaves.

Dicamba’s new role grew out of the success, and then the failure, of glyphosate. After glyphosate-tolerant crops were introduced in 1996, farmers relied heavily on glyphosate alone, and weeds evolved resistance. By the 2010s, glyphosate-resistant Palmer amaranth and waterhemp had spread across the South and Midwest, causing serious yield losses. Monsanto responded by developing soybeans and cotton tolerant to both glyphosate and dicamba, marketed as the Xtend system, so farmers could spray dicamba over the top of growing crops to kill resistant weeds.

The problem was timing and physics. Spraying dicamba in late spring and summer, when temperatures are high and neighboring sensitive crops are growing, greatly increases the risk that it will move off target.

Why Dicamba Drifts

Dicamba can move off the field where it is sprayed in two main ways:

Physical drift. Spray droplets are carried by wind during application. Nozzle choice, boom height, spray pressure, and wind speed all affect this.

Volatilization. After application, dicamba can evaporate from plant and soil surfaces and move as vapor, sometimes hours or days later and over long distances. Volatilization increases with heat. Temperature inversions, when cool air near the ground is trapped under warmer air, typically on calm evenings and early mornings, can concentrate vapor and carry it across the landscape.

Manufacturers developed lower-volatility formulations and additives intended to reduce vapor movement. Weed scientists and many farmers reported that off-target damage continued anyway, especially during hot weather.

The Damage: 2016 to 2021

Problems began even before the new formulations were approved. In 2016, Xtend soybean and cotton seeds were on the market, but EPA had not yet approved the new dicamba herbicides for over-the-top use. Some farmers illegally sprayed older, more volatile dicamba products, causing damage to neighboring crops in several states.

EPA approved the new formulations, including Monsanto’s XtendiMax, BASF’s Engenia, and DuPont’s FeXapan, for the 2017 season. That summer, reports of damage surged across the Midwest and South. University of Missouri weed scientist Kevin Bradley estimated that about 3.6 million acres of soybeans showed dicamba injury in 2017. Damage also affected vegetables, fruit trees, vineyards, ornamental plants, and trees in yards and natural areas. In Arkansas, a dispute over dicamba drift was linked to the fatal shooting of a farmer in 2016, an extreme example of the tensions the issue created in rural communities.

Complaints continued in subsequent years despite additional label restrictions. According to reporting in The Western Producer, EPA received about 3,500 reports of dicamba-related incidents in 2021, including more than a million acres of non-dicamba-tolerant soybeans allegedly damaged by herbicide drift.

Drift damage also had economic consequences that pushed farmers toward the technology. Farmers whose soybeans were not dicamba-tolerant faced the risk of injury from neighbors’ spraying, and some bought dicamba-tolerant seed defensively. Critics argued this dynamic helped the Xtend system achieve rapid market dominance. In 2020, a Missouri jury awarded a peach farmer substantial damages against Bayer and BASF over drift injury to his orchard, a verdict later reduced on appeal, which drew national attention to the issue.

Two Court Rulings

2020: the Ninth Circuit. Farm and environmental groups challenged EPA’s 2018 renewal of over-the-top dicamba. In June 2020, the U.S. Court of Appeals for the Ninth Circuit vacated the registrations of XtendiMax, Engenia, and FeXapan, finding that EPA had substantially understated the risks, including drift damage and the economic and social costs to farmers who did not use the technology. EPA issued new registrations a few months later with additional restrictions.

2024: Arizona. Plaintiffs challenged the 2020 registrations, which covered XtendiMax, Engenia, and Syngenta’s Tavium. As the National Agricultural Law Center explained, a federal district court in Arizona ruled in February 2024 that EPA had violated federal pesticide law, in part by approving the registrations without the required public comment period, and vacated them. Over-the-top dicamba was not approved for use in the 2024 and 2025 growing seasons, though dicamba remained available for other uses, such as in corn.

The 2026 Re-Approval

After the 2024 ruling, Bayer, BASF, and Syngenta reapplied. EPA proposed new registrations in July 2025 and, after public comment, issued a final decision on February 6, 2026. The National Agricultural Law Center reported that the decision covers Bayer’s Stryax, previously known as XtendiMax, BASF’s Engenia, and Syngenta’s Tavium, for the 2026 and 2027 growing seasons, and that EPA will need to make another decision for use in 2028 and beyond. It was the fourth time EPA had approved over-the-top dicamba since 2016, and a coalition of environmental groups promptly filed a legal challenge.

Agri-Pulse reported that EPA described the restrictions as the strictest it had ever required for a dicamba product. They include temperature-based limits: on days with a forecast high between 85 and 95°F on the day of or after application, users may treat only up to half of their untreated dicamba-tolerant cotton and soybean acres in a county, with the remaining acres not treated for at least two days, and no applications may occur if the forecast is at or above 95°F. Other requirements include drift-reduction and volatility-reduction additives, and runoff mitigation practices such as vegetative buffers, contour farming, and cover crops. Farm groups, including the National Cotton Council and American Soybean Association, welcomed the decision as giving growers needed tools and clarity; opponents argued that restrictions had failed to prevent damage before.

State Rules on Top of Federal Labels

States can impose stricter rules on pesticide use than EPA labels require, and several did so during the dicamba disputes. Arkansas, where drift complaints were especially numerous in 2017, restricted in-season dicamba spraying through cutoff dates set by its state plant board, a move that led to legal and political battles with some farmers who wanted access to the technology. Other states, including Illinois and Minnesota, adopted their own cutoff dates or temperature restrictions in some years. State departments of agriculture also investigate drift complaints and enforce label requirements, and the volume of complaints in dicamba years strained some agencies’ inspection capacity.

Who Pays for Drift Damage?

When dicamba damages a neighbor’s crop, compensation is often difficult to obtain. Proving the source of drift, especially volatilization that may travel long distances days after spraying, can be challenging, and damage may come from multiple applicators. Some injured farmers pursue claims through applicators’ insurance or private lawsuits; others absorb the losses to avoid conflict with neighbors. Yield losses from mild leaf cupping are sometimes smaller than the visible symptoms suggest, but severe or repeated exposure can significantly reduce yields, and for specialty crops such as tomatoes, grapes, or organic produce, any injury can be costly. Certified organic farmers face an added risk if residues compromise their certification.

How Volatility Is Measured and Managed

Manufacturers developed lower-volatility dicamba formulations, such as those using diglycolamine or BAPMA salts, along with volatility-reduction agents that keep the spray solution’s pH from dropping, since acidic conditions increase dicamba’s tendency to volatilize. Researchers measure volatility using field experiments with sensitive indicator plants placed at distances from treated fields, enclosed chambers that capture vapor, and air samplers. University weed scientists conducting independent studies have reported that volatilization can still occur under hot conditions even with newer formulations, which helps explain why EPA’s 2026 label focuses heavily on temperature limits. Applicators are also required to follow rules on nozzle types, spray pressure, boom height, wind speed, and avoiding temperature inversions.

The Economics of Adoption

Dicamba-tolerant soybeans spread rapidly after their introduction. Supporters attribute this to their value in controlling resistant weeds. Critics argue that defensive adoption played a role: farmers bought tolerant varieties partly to protect their own crops from neighbors’ dicamba drift. Both factors likely contributed. Seed companies also offered rebates and bundled pricing linking seed and herbicide purchases. When over-the-top dicamba was unavailable in 2024 and 2025, many farmers continued planting dicamba-tolerant seed, which typically also tolerates glyphosate and glufosinate, and used other herbicides, illustrating how the seed trait and the herbicide decision can be separated.

Beyond Soybeans: Trees, Gardens, and Wildlife

Much of the public discussion focuses on damage to non-tolerant soybeans, but dicamba’s effects reach further. Many trees, including oaks and sycamores, show characteristic leaf cupping from exposure, and reports of damaged trees in towns, parks, and natural areas have accompanied dicamba seasons. Vegetable farms, orchards, vineyards, and home gardens near treated fields have reported injury. Native plants in field edges and natural habitats, including flowering plants that provide food for pollinators, can also be affected.

These broader impacts are central to legal challenges, which argue that EPA has not adequately assessed effects on endangered species and their habitats under the Endangered Species Act. EPA has incorporated measures intended to protect listed species into recent registrations, but critics argue the agency still underestimates off-field movement.

Will Weeds Resist Dicamba Too?

Dicamba-tolerant crops were designed to fight weeds that had evolved resistance to glyphosate. Weed scientists warned from the start that heavy reliance on dicamba could lead to the same problem. Populations of waterhemp and Palmer amaranth with reduced sensitivity to dicamba and other auxin herbicides have been reported in some states. The pattern illustrates a basic principle of weed management: any single herbicide used repeatedly will select for resistant weeds. Extension specialists recommend diversifying weed control with multiple herbicide modes of action, pre-emergence herbicides, narrow row spacing, cover crops, crop rotation, and, where practical, mechanical control and harvest weed seed management.

Stakeholder	Main interest	Main concern
Farmers using dicamba-tolerant crops	Controlling glyphosate-resistant weeds	Losing an effective tool; complex label rules
Neighboring farmers	Protecting non-tolerant soybeans and specialty crops	Yield losses from drift; pressure to adopt the technology
Specialty growers and gardeners	Protecting fruits, vegetables, vineyards, trees	Damage with little recourse
Herbicide makers	Selling seed and herbicide systems	Regulatory uncertainty and litigation
Conservation groups	Protecting wildlife and plant habitats	Effects on endangered species and pollinator plants

Alternatives and Competing Systems

Dicamba is not the only option for controlling resistant weeds. Corteva’s Enlist system offers soybeans and cotton tolerant to 2,4-D, another auxin herbicide formulated to be less volatile, along with glyphosate and glufosinate, and it has gained substantial market share. Glufosinate-tolerant crops provide another alternative. Each carries its own risks and resistance concerns. Non-chemical practices, such as cover crops that suppress weed emergence, narrow row spacing that shades out weeds, and tillage where erosion risk allows, are increasingly recommended as part of integrated programs.

What Neighbors and Gardeners Can Do

People who suspect dicamba damage to crops, gardens, or trees can document the injury with dated photos, note symptoms such as cupped or puckered leaves, record weather conditions and nearby spraying if known, and contact their state department of agriculture, which typically investigates pesticide misuse complaints. Collecting plant samples promptly can help, since residues degrade over time. Talking with neighbors who farm, before and during spraying season, can also reduce conflicts; some states and farm groups maintain registries of sensitive crops and apiaries to help applicators avoid them.

A Brief History of Herbicide-Tolerant Crops

Dicamba-tolerant crops are part of a longer story. The first widely grown herbicide-tolerant crops, Roundup Ready soybeans, were introduced in 1996 and transformed weed control by allowing glyphosate to be sprayed over the crop. Their simplicity and effectiveness led to rapid adoption and heavy reliance on a single herbicide, which in turn led to glyphosate-resistant weeds. Industry responded with crops tolerant to additional herbicides, including dicamba, 2,4-D, glufosinate, and others, often stacked so a single variety tolerates several. This approach adds options for farmers, but critics argue it continues a cycle in which new herbicide-tolerant traits encourage heavy herbicide use until weeds evolve resistance again. Our article on consolidation in the seed and pesticide industry describes how these trait systems are tied to the largest companies’ business strategies.

Farmers on Both Sides

The dicamba debate does not divide neatly into farmers versus environmentalists. Many farmers who rely on dicamba-tolerant crops say the technology has been essential for controlling resistant weeds that otherwise devastate yields. Other farmers, including soybean growers who do not use the system, specialty crop producers, and organic farmers, have been among the most vocal critics because they bear the costs of drift. Commodity groups representing soybean and cotton growers have generally supported continued access, while some farm organizations representing smaller and diversified farmers have backed legal challenges. The conflicts have strained relationships between neighbors in some rural communities.

Human Health Considerations

Most attention to dicamba has focused on plant damage, but people also ask about health effects. EPA evaluates dicamba’s human health risks in its registration decisions, including dietary exposure from residues and exposure for applicators, and sets label requirements such as protective equipment. Some epidemiological studies of pesticide applicators have examined possible associations between dicamba use and certain cancers, with mixed and inconclusive results. People applying dicamba should follow label safety requirements, and residents concerned about exposure near treated fields can ask about application timing and keep windows closed during spraying.

Practical Steps for Applicators

For farmers and applicators using dicamba under the 2026 label, extension specialists emphasize several practical steps beyond the legal requirements: check the forecast for both the application day and the following day, since the temperature limits apply to both; scout and communicate with neighbors about sensitive crops, gardens, beehives, and orchards; use the required additives and nozzles and keep sprayers clean to avoid contaminating other applications; avoid spraying during inversions in the early morning and evening; keep detailed records of each application, including weather conditions; and consider whether dicamba is necessary at all, using pre-emergence herbicides and other tactics to reduce reliance on in-season spraying. Careful stewardship is the best way to reduce damage and preserve access to the tool.

Lessons for Pesticide Regulation

The dicamba saga offers several lessons about how pesticides are regulated. Predicting real-world behavior from controlled studies is difficult: lower-volatility formulations performed better in tests than many farmers observed in fields during hot summers. Off-target impacts on people who did not choose the technology, including neighboring farmers and gardeners, raise questions about how to weigh benefits to users against costs to others. Courts have repeatedly found that EPA did not adequately account for these risks or follow required procedures, underscoring the importance of transparent analysis and public comment. And short-term registrations with data collection, as in the 2026 decision, reflect an effort to learn from experience, but they also create uncertainty for farmers who plan seed purchases months in advance.

Supporters of the technology argue that the restrictions, combined with improved formulations and applicator training, can allow farmers to use an important tool while protecting neighbors. Critics argue that a herbicide prone to volatility should not be sprayed in summer over large acreages, no matter the restrictions. The next two seasons will provide evidence for both sides.

Dicamba in Corn and Other Uses

The court rulings and the 2026 decision concern over-the-top use on dicamba-tolerant soybeans and cotton. Dicamba also remains registered for other uses, including in corn, small grains, pastures, and some non-crop areas, typically applied earlier in the season or at lower rates. These uses have a longer history and have caused fewer widespread drift problems, though applicators still need to follow label precautions near sensitive crops. Homeowners may also encounter dicamba as an ingredient in some lawn weed killers, which carry their own label directions.

Understanding Dicamba Injury Symptoms

Recognizing dicamba injury helps farmers, gardeners, and investigators. In soybeans, the most characteristic symptom is cupping of new leaves, which curl upward into a cup shape, often with crinkled edges. Other broadleaf plants may show twisted stems, strap-like or puckered leaves, and distorted growth at growing points. Tomatoes, grapes, and many ornamentals are especially sensitive. Symptoms typically appear several days to a couple of weeks after exposure and affect new growth more than older leaves. Because other herbicides and environmental stresses can cause similar symptoms, laboratory testing of plant tissue soon after symptoms appear can help confirm the cause. The pattern of injury across a field, such as a gradient from one edge, can also indicate drift from a particular direction.

Questions Neighbors Can Ask Before Spraying Season

Will nearby fields be planted with dicamba-tolerant crops this year, and will over-the-top dicamba be used? Can applicators notify neighbors before spraying? Are sensitive crops, gardens, orchards, and beehives registered in a state sensitive-crop registry? What buffer practices will be used near property lines? Having these conversations early can prevent disputes and help everyone plan.

What to Watch

The legal challenge. Environmental groups have sued over the 2026 registration. A court could again vacate the approval.

Incident reports. The number and severity of drift complaints in 2026 and 2027 will be a key test of whether the new temperature limits work.

EPA’s 2028 decision. EPA has said it will review the collected data after the two seasons before deciding whether to allow over-the-top use beyond 2027.

Weed resistance. Reports of dicamba-resistant weeds will affect the technology’s long-term value.

State actions. States may impose additional restrictions based on local experience.

Further Reading

For updates, readers can follow EPA’s dicamba announcements, state department of agriculture guidance, university extension weed science programs, which publish practical recommendations and drift research, and analyses from the National Agricultural Law Center on the legal developments. Reading perspectives from farm organizations, environmental groups, and independent scientists provides the fullest picture of a contested issue.

University extension services in soybean and cotton states also publish annual summaries of drift complaints and research findings from field trials, which provide independent data to compare with company and regulatory claims.

Growers deciding whether to plant dicamba-tolerant varieties in 2027 and beyond should also watch for court rulings in the pending lawsuit, since a vacatur could again change what is allowed mid-planning cycle. Discussing contingency weed control plans with agronomists, including options that do not depend on over-the-top dicamba, reduces the risk of being caught without an effective program.

Home gardeners near farm fields can protect especially sensitive plants, such as tomatoes and grapes, by noting spray schedules, covering small plants during nearby applications when practical, and documenting any injury promptly.

Beekeepers near treated fields have their own concerns, since drift can damage flowering plants that bees depend on. Registering hives in state apiary or sensitive-site registries, where available, helps applicators know where extra care is needed.

Key Terms

Over-the-top application: Spraying a herbicide over a growing crop after it has emerged.

Volatilization: The evaporation of a pesticide from surfaces after application, allowing it to move as vapor.

Temperature inversion: A weather condition in which cooler air near the ground is trapped under warmer air, allowing vapor and fine droplets to concentrate and move.

Auxin herbicide: A herbicide that mimics plant growth hormones, such as dicamba and 2,4-D.

Registration: EPA approval for a pesticide product to be sold and used under specific label conditions.

Vacatur: A court order voiding an agency decision.

The Bottom Line

Dicamba-tolerant crops were a response to glyphosate-resistant weeds, but spraying a volatile herbicide during the growing season created a new problem: widespread damage to neighbors’ crops, gardens, and trees, and deep divisions in farm communities. Courts struck down EPA’s approvals twice, and the agency has now re-approved three products for 2026 and 2027 with its strictest restrictions yet, including temperature limits. Whether those restrictions prevent the damage seen in earlier years, and whether the approval survives a new legal challenge, will determine dicamba’s future and offer lessons about how herbicide-tolerant crop systems should be regulated.

Frequently Asked Questions

What is dicamba?

A synthetic auxin herbicide used since the 1960s that kills broadleaf weeds. Genetically engineered dicamba-tolerant soybeans and cotton allow it to be sprayed over growing crops.

Why is dicamba controversial?

When sprayed in warm weather, it can drift or volatilize and damage neighboring crops, gardens, and trees. Millions of acres of soybeans were reported injured in some years.

Is dicamba banned?

No. Over-the-top use was blocked by courts for the 2024 and 2025 seasons, but EPA re-approved three products for 2026 and 2027 with new restrictions. Other dicamba uses, such as in corn, continued.

What changed in the 2026 rules?

New temperature-based limits, including no applications when the forecast is 95°F or higher, limits on acreage treated on hot days, required additives to reduce drift and volatility, and runoff mitigation practices.

Is Stryax the same as XtendiMax?

Stryax is Bayer’s dicamba product registered in 2026, previously known as XtendiMax.

Is dicamba harmful to people?

Dicamba’s main documented harms involve plants. Human health questions are evaluated by EPA in its risk assessments; people applying it should follow label safety requirements.

References

1. National Agricultural Law Center. The Deal with Dicamba: Court Vacates Over-the-Top Registration. 2024. nationalaglawcenter.org
2. National Agricultural Law Center. The Deal with Dicamba: Products Registered, Lawsuit Filed. 2026. nationalaglawcenter.org
3. Agri-Pulse. EPA approves over-the-top use of dicamba for two years. February 2026. agri-pulse.com
4. The Western Producer. U.S. soy and cotton growers might use dicamba in 2026. 2025. producer.com

Last updated: October 1, 2026