So I finally broke down and built a halfway decent coop for the flock. All the bells and whistles are there, plenty of space, plenty of food / H2O, etc... Their old coop was one of my ghetto creations made from old shipping pallets and tin roofing. They basically moved from a shack into a nice...
See if you can obtain the MSDS sheets from the city/town that correspond with the pesticide. Those should give a good description of the hazards of the chemicals. They shouldn't have a problem providing you that information- they're intentionally releasing the pesticide into your environment so...
I wouldn't do that- You'll just give local predators a target to go for even after you deem it safe and fill it with chickens. Don't make yourself a target.
Sorry to hear, I would recommend pleading ignorance to the law and culling anyway somehow. Otherwise you could probably go to the local vet and ask that they euthanize her for you. I'm sure they would not have a problem doing that for you to alleviate the suffering of the bird.
Forgot to update- she lasted about two more days with no improvement before she gave up the ghost. None of the other birds shows any trouble so I'm going with the assumption that this was an isolated neurological defect in the one bird. Thanks for the insight guys!