7 C.F.R. § 352.9
The arrival, unloading, landing, or possession of plants, plant products,plant pests, biological control organisms, noxious weeds, soil, or other products or articles subject to this part shall not be allowed at points within the United States other than at the ports specified in the Customs Regulations in 19 CFR 1.1 and 19 CFR 6.13 , and Agana, Guam, or such other ports as may be named in permits or administrative instructions. Restrictions on the ports which may be used for particular types of handling of any products or articles subject to this part may be specified generally in administrative instructions or in permits in specific cases. When ports are specified in permits or otherwise, the arrival, unloading, landing, or possession of the products or articles involved at other ports will not be allowed except as the inspector may authorize changes in the ports specified.
7 C.F.R. §352.9