The California Department of Pesticide Regulation's (DPR's) Pesticide Use Report (PUR) is probably the largest and most complete database on pesticide use in the world. A system to collect information on pesticide use in California has been in operation in some form for over 50 years, with the current use reporting system started in 1990. The PUR contains information on nearly all production agricultural pesticide use and some nonagricultural use in California. The data collected include the pesticide product used, the date it was applied, the particular field treated, and application location to a square-mile section. Production agricultural use includes applications to growing crops, agricultural fields, and most applications to forest trees and ornamental turf. Other pesticide uses reported to DPR include post-harvest commodity treatments, right of way, landscapes, structural use, and other nonagricultural uses by commercial applicators. Because of the importance of the PUR for many groups and individuals, it is critical that the database be an accurate and complete as possible.