This final rule amends the pesticide tolerance regulation for diazinon by modifying the revocation of the tolerance for mushrooms. Pesticide tolerances are established under the Federal Food, Drug, and Cosmetic Act (FFDCA). This final rule resolves an objection filed by the American Mushroom Institute in response to a final rule on diazinon tolerances published on September 10, 2008, by granting the objection and modifying the revocation of the diazinon tolerance on mushrooms to expire on September 10, 2010.