The power company gave me no warning, the neighbor did come over and talk with me about it and told me he would be very careful not to spray my plants and would do it on a calm morning. I did appreciate that!
I don't think it was a question of green plants being superior or inferior to dead ones, but I think the dead dried vegetation was just much easier to mow with the bush hog. The green vegetation tends to want to wrap around and clog up the machinery. Plus too, I think there was a safety factor. With all the green vegetation, the operator of a tractor or large piece of equipment is not able to see the holes and washes in the fields that could cause a tractor to turn over.