Cal. Food & Agric. Code § 52301
(a) Before a person or his or her agent holding a patent on a genetically engineered plant, may enter upon any land farmed by another for the purpose of obtaining crop samples to determine whether breach of contract or patent infringement has occurred, the person holding the patent or his or her agent shall do all of the following:
(4) Provide notice to the farmer of the following procedures which shall be applicable as provided: