Years ago, probably 25 years ago, before we sprayed all our own ground (we had a deere 550 sprayer)  Most of our spraying was done by a custom guy.  We bought a lot of our own chemicals, he'd mix them on the farm and spray with a floater truck.  He done a real good job for the times.  Cheaper than hiring a coop, and as mentioned, was there when you needed him.