:For other uses, see pesticide application, spray and spraying and spray bottle. A sprayer is a device used to spray a liquid. In agriculture, a sprayer is a piece of equipment that applies herbicides, pesticides, and fertilizers to agricultural crops. Sprayers range in size from man-portable units (typically backpacks with spray guns) to self-propelled units similar to tractors, with boom mounts of 60-151 feet in length. Types Backpack/knapsack Foot Garden Hand compression Power Stirrup… (More on Sprayer)