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New WSSA Backgrounder Clarifies Purpose and Use of Plant-Back Intervals

WESTMINSTER, Colorado – June 27, 2022 – Plant-back intervals are a critical component of any pesticide label – indicating the minimum period of time between a pesticide treatment and the planting of your next crop. But experts say some confusion lingers about the purpose and use of these important requirements. Are they designed to protect crops or to protect human health? Do they apply to all plantings or just to crops that will be consumed?

A presentation during the 2022 annual meeting of the Weed Science Society of America (WSSA) provided clarity on why plant-back regulations exist and how they should be applied. That information is now summarized in a new WSSA backgrounder available for free online.  Among the key points covered:

  • Plant-back intervals are established by the U.S. Environmental Protection Agency (EPA) to protect humans from over exposure to pesticide residues. These research-based intervals are based on residue studies that include all pesticides applied within the current and previous growing seasons.
  • Plant-back restrictions must be observed if the crop to be planted will be harvested for human consumption or will be grazed by or fed to livestock that will be consumed by humans. The restrictions do not apply to cover crops planted solely to improve soil quality, reduce erosion or manage weeds since there is no risk of dietary exposure.
  • Plant-back intervals are NOT designed to address adverse effects on the crops themselves. Pesticide companies may choose to add label guidance to address phytotoxicity concerns, but these instructions are independent of EPA-mandated plant-back restrictions that focus on limiting human exposure to pesticide residues.

Want to know more? Download the WSSA backgrounder or take a deeper dive by exploring the original poster presentation.


About the Weed Science Society of America

The Weed Science Society of America, a nonprofit scientific society, was founded in 1956 to encourage and promote the development of knowledge concerning weeds and their impact on the environment. The Society promotes research, education and extension outreach activities related to weeds, provides science-based information to the public and policy makers, fosters awareness of weeds and their impact on managed and natural ecosystems, and promotes cooperation among weed science organizations across the nation and around the world.  For more information, visit www.wssa.net.

Press Contact:
Lee Van Wychen 
Executive Director of Science Policy
National & Regional Weed Science Societies
[email protected]