2025 Update On Plant Biostimulant Product Regulation Under FIFRA

Key Takeaways

• What Happened: Efforts to develop a federal definition for plant biostimulants are ongoing, but the marketplace continues to face confusion over what this product category is and how it is regulated.
• Who's Impacted: Companies that produce, distribute, and/or sell products that make plant biostimulant claims.
• What Companies Should Consider Doing in Response: Companies should monitor for new developments from Congress, the U.S. Environmental Protection Agency (EPA), and the U.S. Department of Agriculture (USDA), while considering EPA's 2020 "Draft Guidance for Plant Regulators and Claims" to be the most current expression of federal policy related to plant biostimulants to date.

Background

Growing interest in sustainable agriculture has increased demand for plant biostimulant products that enhance natural plant processes to improve crop performance. In general, plant biostimulant products refer to biological or chemical substances applied to physiologically "stimulate" plants. This stimulation can result in benefits such as increased crop quality or yield, improved nutrient efficiency, or higher tolerance to stress.

Questions about the regulatory status of plant biostimulants have persisted for years. The definition of "pesticide" under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) extends beyond substances intended to "[prevent, destroy, repel, or mitigate]" pests to include, among other things, "plant regulators." FIFRA defines a plant regulator to include "any substance or mixture of substances intended, through physiological action, for accelerating or retarding the rate of growth or rate of maturation, or for otherwise altering the behavior of plants or the produce thereof."

In some instances, plant biostimulants may be associated with plant regulator claims, which in turn triggers regulation as a pesticide product under FIFRA. But not all plant biostimulant products fit the definition of plant regulators, leading to widespread uncertainty about which of these products may be subject to regulation as pesticides under FIFRA.

In March 2019, EPA released a draft guidance document that attempted to clarify which biostimulant products the Agency considers within FIFRA's definition of plant regulator. In November 2020, EPA released an updated draft in response to public comments received on the 2019 guidance. (For an overview of key differences between the 2019 and 2020 guidance documents and potential implications, see B&D's alert here).

EPA's guidance did not advance an independent definition of "plant biostimulant," but instead drew upon definitions of the term outlined in the 2018 Farm Bill and the 2019 USDA Report to Congress on Plant Biostimulants. With these definitions in mind, EPA's guidance explains that a biostimulant product will be subject to regulation as a pesticide under FIFRA when its marketing claims and composition fall within the definition of a plant regulator. As described in EPA's guidance, this approach leads to scenarios where a biostimulant product that claims to "[improve] soil/seed nutrient conditions for root growth" may in some instances be considered non-pesticidal, while a similar product that claims to be a "root/shoot stimulator" will generally require registration as a pesticide.

EPA has not finalized the 2020 draft guidance to date, although the document remains available on the Agency's regularly updated website. At this time, the draft stands as the most current expression of EPA's approach to plant biostimulants under FIFRA.

Implications for Potentially Impacted Entities: Recent EPA Enforcement and Federal Legislative Initiatives

EPA has assessed several significant penalties in connection with plant biostimulant products since first releasing its draft guidance in 2019. In May 2020, for example, EPA assessed a $300,000 penalty against Bio-Cat, Inc. and Bio-Cat Microbials, LLC based on allegations that, among other things, the companies sold unregistered pesticides with plant growth and stimulant claims. Consistent with its draft guidance, EPA focused on product claims to promote root, shoot, and plant growth and higher yields. The products also contained gibberellic acid and cytokinins, which are identified as presumptive pesticidal active ingredients in EPA's draft guidance.

Similarly, in 2022, EPA assessed a $437,000 penalty against Douglas Plant Health Intermediate, Inc. based on allegations that, among other things, the labels contained claims of root stimulation, foliar formulation, and accelerated growth, which EPA determined indicated pesticidal intent that required FIFRA compliance.

Notwithstanding these examples, EPA has not publicly signaled that it will finalize the draft plant biostimulant guidance anytime soon. At the same time, there are currently two parallel bills in Congress that would amend FIFRA to expressly exclude biostimulants from the definition of plant regulators (and thus from FIFRA regulation altogether). The Plant Biostimulant Act of 2025, introduced to the Senate on May 22, 2025, would amend FIFRA's definition of plant regulator to exclude biostimulants that "(i) are of biological origin" or "(ii) include chemical compounds that are synthetically derived, but are structurally similar and functionally identical to substances of biological origin." The bill also newly defines the term plant biostimulant to mean "a substance, microorganism, or mixture thereof, that, when applied to seeds, plants, the rhizosphere, soil, or other growth media, acts to support a plant's natural processes independently of the nutrient content of that substance, microorganism, or mixture thereof, and that thereby improves— (1) nutrient availability, uptake, or use efficiency; (2) tolerance to abiotic stress; and (3) consequent growth, development, quality, or yield." The Senate has taken no further action on the bill since May.

A similar bill was introduced to the House on June 5, 2025, proposing the exact same amendments to FIFRA. H.R. 3783 was referred to the House Committee on Agriculture, but the House has taken no further action on the bill since June.

Passage of these bills this year is still possible, but seems unlikely. Notably, this is not the first time a bill proposing to exclude biostimulants from the definition of plant regulators under FIFRA has been proposed. In fact, similar bills were introduced in the House in 2022 and in 2023, although neither advanced past the committee stage. Additionally, in 2024, members of both houses attempted to exclude plant biostimulants from the definition of plant regulator under FIFRA through amendments to the Farm Bill. The Committee on Agriculture ordered the bill to be reported, but it never advanced.

Next Steps

While it is unlikely that a Plant Biostimulant Act will advance in Congress before the end of the year, plant biostimulants will almost certainly remain a focus of future regulatory, legislative, and enforcement efforts. For the time being, manufacturers and distributors of these products should continue to take EPA's draft 2020 guidance into account when developing their regulatory compliance approaches.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.