California Code, Food and Agricultural Code (Formerly Agricultural Code) - FAC § 5701

(a) If any pest exists on any premises, the director or the commissioner may hold any plant or other host or possible carrier which is, or may be, capable of disseminating or carrying the pest.The director or the commissioner also may hold the plants, other hosts, or other possible carriers on any premises within five miles of the premises on which the pest was found to exist. The director or commissioner shall notify the owner of the plant or other host or possible carrier, or his or her agent, of this action, and the issuance of any shipping permit or nursery stock certificate with respect to the plant or other host or possible carrier shall be refused and any such permit or certificate which has been previously issued shall be revoked.

(b) The distance from the premises at which a pest is found that the director or commissioner may hold plants, other hosts, or other possible carriers shall be the maximum distance that the director or commissioner determines the pest is likely to travel, but not to exceed five miles.