This from an actual farmer in the UK:
While touring a (small) organic farm the question came up what they did about certain rather nasty weeds. Once these  get into the ground they are very hard to get rid of - for a family operation it's just not possible to put in the amount of work required.
The answer is that you use a lot of pesticides, then go organic the next year. Problem solved.

I'm sure "organic" appeals to us armchair intellectuals with our nice desk jobs, but someone will have to do the work.