This final rule clarifies the distinction between "isolates" and "strains," and clarifies the requirements applicable to new isolates, which are considered to be new active ingredients under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Additional revisions to regulatory text include several minor corrections to words and references. Finally, EPA is announcing the availability of a final microbial pesticide test guideline that further explains the existing data requirement to deposit a sample in a nationally recognized culture collection. Collectively, the final rule clarifications and revisions, as well as the final microbial pesticide test guideline, are expected to enhance the ability of industry to efficiently manage its microbial pesticide registration submissions.