[QUOTE=Ixixly;
Hells beiis, where do we start.
The handling and application of a pesticide is controlled by its label. This is a legal document so the applicator is required by law to obey the label. The label will state if the pesticide can be aerially applied and to which crop and to which target pest.
It will state how much of the pesticide active ingredient must be applied per hectare. It is illegal to apply a lower rate. A lower rate won't necessarily give total control of the target pest and pesticide resistance can develop in the target population. The label can state the droplet size to be used.
The window of optimal conditions for application can be quite small. The spray droplet has to survive the journey from the aircraft to the crop canopy. A combination of temperature and humidity may mean the droplet completely evaporates before it hits the target. So if there is 500 hectares to spray before it gets too hot at 10am you better go with the airtractor option.
The application company and the pilot have to be licensed by state authorities to handle and apply pesticides. Spray liability insurance is a requirement. Off target damage can be expensive.
The ag aircraft is set up to lay down a spray swath of known dimensions. It is set up to minimise aerodynamic entrapment. Spray droplets ending up in the tip vortex can look impressive but it means fine droplets can move off target. The down wash coming off the wing is highly effective at driving the spray cloud into the crop.
The ag pilot arriving over a treatment area is carrying out an extensive due diligence. Haven't seen a map, digital or otherwise that I would trust. Life is full of surprises and low level you don't want them. While you are working a field anything can and does pop up. Sometimes you just have to pull off and go a mile away and fly some orbits until the conflict moves away.
So a drone operator sitting on the tailgate of his ute a mile or so away is going to have trouble controlling his work environment.