Iowa Code § 206.15: Licensee to keep records.

The secretary shall require commercial applicators and certified commercial applicators to maintain records with respect to application of pesticides. Such relevant information as the secretary may deem necessary may be specified by regulation. Such records shall be kept for a period of three years from the date of the application of the pesticide to which such records refer, and the secretary shall, upon request in writing, be furnished with a copy of such records forthwith.