This regulation establishes a tolerance for combined residues of fosthiazate (O-ethyl S-(1-methylpropyl)(2-oxo-3- thiazolidinyl)phosphonothioate and its metabolite O-ethyl S-(1- methylpropyl)[2-(methylsulfonyl)ethyl] phosphoramidothioate (ASC-67131) in or on tomato. ISK Biosciences requested this tolerance under the Federal Food, Drug, and Cosmetic Act (FFDCA), as amended by the Food Quality Protection Act of 1996 (FQPA). This tolerance will support the use of fosthiazate on tomatoes as a replacement for methyl bromide for the control of nematodes.