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Breakthrough for Hemp Growers: Ethalfluralin 1st Conventional Pesticide Tolerance Announced by EPA


Explore how the EPA’s approval of a conventional pesticide tolerance for ethalfluralin is reshaping the hemp industry. 


In a groundbreaking move, the U.S. Environmental Protection Agency (EPA) recently unveiled a milestone achievement for hemp cultivation – the approval of the first conventional pesticide tolerance for hemp seed. This decision stands as a remarkable triumph not only for The IR-4 Project but also for hemp growers in search of enhanced pest management tools. The approved conventional herbicide, ethalfluralin, already in use for crops like soybeans, peanuts, and potatoes, empowers hemp growers in their battle against annual broadleaf and grassy weeds, which often hinder the growth of young plants.

While bio-based pesticides were previously accessible for hemp cultivation, growers have seen an echoing demand for a broader range of tools to ensure successful large-scale hemp production. As Dr. David Suchoff, Alternative Crops Extension Specialist at North Carolina State University, emphasized, “The addition of another tool to our limited IPM toolbox is of utmost importance. Weeds, particularly in the Southeast, pose the most significant challenge to our efforts. Our trials using ethalfluralin have exhibited exceptional weed control, with a few exceptions like nutsedge.”

Since the 2018 Farm Bill greenlit hemp production and removed it from the list of controlled substances, interest in cultivating this versatile plant has soared. However, the heightened interest also gave rise to the need for approved pest management solutions. The IR-4 Project, in collaboration with partner agencies and researchers, has been dedicated to generating data and facilitating product registration that caters to the demands of hemp growers. The newfound tolerance for ethalfluralin marks a significant stride forward.

The Ethalfluralin Tolerance Journey

Navigating the regulatory landscape for pest management products tailored to hemp presented a significant challenge to the EPA. Given hemp’s relatively new status as a mainstream crop, uncertainties loomed over what residue studies should encompass, which parts of the plant to examine, and the kinds of risks that warranted assessment. It was uncharted territory, to say the least.

Nancy Fitz, Minor Use Team Leader at EPA’s Office of Pesticide Programs, acknowledged the indispensable role of IR-4 in guiding EPA through this uncertain terrain. The project emerged as a crucial source of expertise in this context.

IR-4 promptly embarked on gathering data that could be extrapolated to help the EPA evaluate potential risks linked to ethalfluralin’s use on hemp seed. Some data was drawn from studies conducted in Canada, facilitated by IR-4’s longstanding collaboration with the Canadian Pest Management Centre, which expedited data collection and the petition process.

Jerry Baron, Executive Director of The IR-4 Project, explained, “We leveraged Canadian data and formulated a ChemSAC proposal urging EPA to consider, based on a comprehensive body of evidence, that no residue would remain in the hemp harvest following ethalfluralin application. This compound exhibited no residues in plants and did not translocate.”

In October 2020, IR-4 submitted a petition to the EPA, requesting the establishment of tolerances for ethalfluralin residues on hemp seed and several other crops. Based on the petition, the EPA issued a final rule on April 10th, enacting these tolerances.

A Leap Toward Success

This newly established tolerance for ethalfluralin in hemp seed was preceded by a thorough human health risk assessment by the EPA. According to the agency, “The tolerance for residues of ethalfluralin in or on hemp seed is grounded in meticulously considered scientific rationale, utilizing ethalfluralin residue field trial data from various other crops. Using ethalfluralin on hemp is unlikely to pose unreasonable risks to people or the environment.”

EPA has already embraced updated ethalfluralin labels, with usage instructions for hemp seed and other crops. However, growers must await the product label’s update before integrating it into their hemp cultivation practices. The maximum waiting period for this label update is set at 18 months. After this period, any distribution or sale of Sonalan HFP (101-63-356) must adhere to the approved labeling.

For more detailed insights into the EPA’s ethalfluralin tolerance decision, one can explore the final rule and scientific analysis in docket EPA-HQ-OPP-2021-0130 at

IR-4’s Role in Addressing Evolving Hemp Pest Management Needs

In the realm of data, experience, and regulatory preparedness, hemp is still in its early stages, especially compared to other crops. IR-4, working with Cooperative Extension and land-grant researchers nationwide, is diligently researching pest management strategies to bolster hemp cultivation in this burgeoning industry.

Hemp’s various applications – for its flower, fiber, seed, or feed – entail harvesting at distinct life cycle stages, each presenting different pest-related challenges. Weed management predominantly comes to the fore during the seedling phase, while disease and insect pressures escalate as the plants mature.

Cole Smith, IR-4 Field Research Director at NC State University, emphasized, “IR-4 is actively exploring a range of solutions to tackle foliar and root pathogens, mites, and grassy weeds. With the shifting market focus on fiber, weed management is gaining significance for hemp growers.”

Bert James, a hemp grower and agricultural consultant based in North Carolina, shed light on the disparity between the public’s vision of minimal pest management and the practical needs of growers striving to cultivate thriving hemp crops. “While there’s a strong desire to maintain hemp as a clean and relatively pesticide-free crop, this aspiration doesn’t always align with the diverse range of farmers in our region,” shared James. He further emphasized the need to strike a balance and recognize hemp as a crop deserving of investment and development.

Regarding the newly established ethalfluralin tolerance, James added, “The arsenal of chemical tools available for hemp will inherently be limited due to the plant’s unique characteristics. What’s imperative is for everyone to allow hemp to evolve as a crop that can be seamlessly integrated into rotations, becoming just another crop we can nurture and enhance.”

Paving the Path Ahead

The acceptance of ethalfluralin tolerance on hemp seed represents the initial stride toward an enriched and extended arsenal of pest management tools for hemp producers. IR-4 remains optimistic about the future prospects of hemp, which holds potential not only in terms of seed and extract but also in areas like fiber, construction materials, animal feed, and soil remediation. According to Jerry Baron, “Though the initial hype around hemp, particularly for CBD, may have waned, it’s poised for a resurgence. The versatility of hemp opens doors to various applications, and the next step is securing approval for more pest management products.”

As the journey unfolds, IR-4 continues its commitment to prioritize and fund hemp field trials, generating data crucial for both growers and the EPA. In the upcoming year, IR-4 is set to submit the first petition containing actual hemp residue data, marking a significant step forward. Stakeholders seeking to contribute to hemp pest management research can submit their suggestions through a Project Request. New hemp studies are prioritized at the Food Use Workshop each September.

The ethalfluralin tolerance granted for hemp seed is just the beginning of an extensive toolkit to fortify the hemp industry. As we look ahead, IR-4 is poised to witness the progression as growers embrace novel tools for cultivating resilient, healthy hemp crops.


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