No person shall act, or offer to act, as an agricultural pest control adviser without first having secured an agricultural pest control adviser license from the director. Officials of federal, state, and county departments of agriculture and the University of California personnel engaged in official duties relating to agricultural use are exempt from this section if any recommendation by any of these persons as to a specific application on a specific parcel is made in writing. Officials of districts formed pursuant to Chapter 4 (commencing with Section 5780) of Division 5 of the Public Resources Code are exempt from this section until July 1, 1995, if any recommendation by any of these persons as to a specific application on a specific parcel is in writing.