California Code, Food and Agricultural Code (Formerly Agricultural Code) - FAC § 5492

If any pest is found to exist in any park or along any street, highway, right-of-way, or other property which is subject to the control of any agency of the state, the director, upon receiving a report of the existence of the pest from the commissioner, shall notify the agency.  He may instruct the commissioner to serve the notice upon the director or other executive officer of the agency.  If the eradication, control, or destruction of the pest is performed by the commissioner, the cost of the eradication, control, or destruction is a charge against, and shall be paid from, the maintenance fund or from other funds for the support of the agency.

This section applies to a state highway right-of-way if any pest of the same kind has been, or is being, subjected to control, destruction, or eradication on other private or public property in the immediate vicinity of the right-of-way, either at the direction of the commissioner or voluntarily by the owner of such adjacent property.