An agricultural aircraft is an aircraft that has been built or converted for agricultural use - usually aerial application of pesticides (crop dusting) or fertilizer (aerial topdressing); in these roles they are referred to as "crop dusters" or "top dressers". Agricultural aircraft are also used for hydroseeding.
The most common agricultural aircraft are fixed-wing, such as the Air Tractor, Cessna Ag-wagon, Gippsland GA200, Grumman Ag Cat, M-18 Dromader, PAC Fletcher, Piper PA-36 Pawnee Brave and Rockwell Thrush Commander but helicopters are also used.
Read more about Agricultural Aircraft: Early Use of Aircraft in Agriculture, Agricultural Aircraft Designs, Techniques, Conflicting Views On Aerial Spraying