Agricultural pilot reported a NMAC with a UAS that was crop-spraying in a nearby field. The pilot stated the UAS operator appeared to not have visual contact with their UAS while flying it and did not adjust the UAS flight path to avoid the fixed wing aircraft.

Narrative

While acting as PIC of an Air Tractor 602 hauling a load of pesticides; I got to my fields and saw a drone and its tender truck spraying a field under a quarter mile away. I flew a parallel path to the drone E and W on the first field. The drone continued operating and spraying during that time. After roughly 12 minutes; I had finished my first field and moved to the one that put me on an E and W path with my turns being required over the drone operation. I did a circle around and puffed smoke to get the drone operators attention; and they kept spraying and flying it. I then began my application runs and turned out over the operator and drone while it was flying. This involved roughly 25 or so passes that put me over them. As my aircraft was nearly fully loaded; my turns occurred at low levels which put me roughly 100 ft. above the drone while I crossed its path. They continued to fly the drone and spray the field and even landed; reloaded; and flew it more during this time. The drone operator was on the bottom part of a multi-level trailer and never acknowledged my aircraft's or smoke signal attempts. From their view I am almost positive that they had no way to view their drone while it was flying either.