Diphacinone treated baits have recently become Federally Restricted Materials by the US EPA and will only be available for purchase by "certified applicators" beginning June of 2011.
All field use rodenticide product labels will be amended to add the Federally Restricted Use designation. Residential use will also be removed from the new labels.
Due to this change, diphacinone treated bait will no longer be available to the Agriculture Department.
Gas cartridges (smoke bombs) are still available at the Ag Department for ground squirrel control.