You hit one of my personal gripes with flying in the windmills right on the head... While they are not as precarious to fly in / under / around as they look, they are time consuming. In fact, by my estimation, flying in an average wind turbine farm takes an average of twice as long, to do a less than perfect job. You will leave pie shaped pieces untreated where the turbines live, and have to deal with the ones in the middle of the field, that goes without saying. But generally it's the ones just outside your field that are going to cost you the most heartache and time. Most of the spinning fans are on the order of 200' wide, and 300' tall. That takes a huge piece of airspace that you can't just remove from the corresponding swaths on your field, and most ag ops are running swaths in the 60' - 75' range. So at a minimum, three of your turns are going to have to be extremely modified to get you back to the entry point and track you need to be on per turbine. And they wouldn't call it a wind turbine farm if there was just one to deal with...
Then there's the issue of what they're doing to the air, both in the field and in your turn.
Then there is the human component. Humans make mistakes. Screw the pooch and hit a wire, and odds are, it's going to turn out ok, for everything except your pocket book...Hit one of these guys, and it's most certainly going to bring you down... And it's probably not going to turn out well.
Lastly, there is the cost of these monstrosities... I happen to know for a fact that very few people carry insurance that would cover the cost of rebuilding a turbine... So long after you get buried your operator is still going to be paying...
Some people have suggested turning them off before you spray... that is because they aren't the ones trying to juggle the day to day ag op.. that notion is a fantasy perpetuated by the turbine salesman... In short, it's just not going to happen when you get tasked with the job.
Two of us at our outfit still fly them... but IMHO if they doubled the pay on the fields with turbines in them, and then offered me a choice, I'd probably still pass on them... Until then I just keep with the notion that sometimes you gotta take the bad fields to get to the good ones...
Take care, Rob