List 3 Inerts

I would like to formulate a foliar spray or ground application crop pesticide that will include a synthetic inert ingredient from EPA List 3. Are List 3 inerts allowed in pesticides used in organic production?

By Doug Currier

Yes and no. As with all allowed synthetic materials, synthetic inerts allowed for use in pesticide formulations are listed at §205.601 of the National List of Allowed and Prohibited Substances. For foliar or ground application pesticides, the NOP rule at §205.601(m)(1) currently only allows synthetic inert ingredients that appear on the EPA’s 2004 List 4a and 4b (inerts of minimum concern) for inclusion in pesticide formulations used in organic production.

Foliar and ground application pesticides are pesticide products that are directly applied to crops or soil. The EPA’s full 2004 list of inerts is located at https://www.epa.gov/epcra/consolidated-list-lists. Synthetic List 3 inerts (inerts of unknown toxicity), as detailed at §205.601(m)(2) of the NOP Rule, are allowed for use in crop pesticide formulations, but only in passive pheromone dispensers. In other words, pesticide products that use pheromones as an active ingredient may include List 3 inerts, as long as the method of administering the pheromone is through a passive dispenser. List 3 inerts therefore can not be used in pesticide products for foliar or ground application, but can be used in pheromone products. These pheromone products must, however, carry a restriction.

Passive dispensers include products which emit pheromones by volatilization, rather than by directly spraying crops or soil. These methods are effective at producing a concentration of pheromones in a limited area. Examples of passive methods include twist ties, ropes, coils, wands, and other retrievable dispensers where the active pheromone is not in contact with the crop or soil.

It should be noted that a product containing a pheromone active ingredient and formulated with either List 4 inerts, nonsynthetic ingredients, or synthetics allowed at §205.601 may be used without the List 3 restriction. Any synthetic List 1 (inerts of toxicological concern) or List 2 (potentially toxic inerts) inerts are prohibited in organic production under 7 CFR Part 205.

This article originally appeared in the winter 2012 issue of the OMRI Materials Review newsletter, and was revised in May 2024 by Research and Education Manager Peter Bungum.