1. Chapter 17.21 RCW authorizes the Department of Agriculture to regulate pesticide application and use. This chapter preempts cities and counties from regulating pesticide application and use, except the first class cities and the counties in which they are located can regulate structural pest control operators, exterminators, and fumigators. 2. Chapter 15.58 RCW authorizes the Department of Agriculture to regulate formulation, distribution, storage, and disposal of pesticides. This chapter does not preempt cities and counties from regulating these activities, so long as the local regulations do not conflict with state law.
A commercial pesticide applicator license is required for any person in the business of applying pesticides to lumber located on the land of another; however, a private-commercial applicator license is sufficient for persons whose business is limited to applying pesticides to lumber located on their own land, no matter who owns the lumber.