kayo
It is really awful to feel like you don’t have any recourse or way to stop this. One of our dogs may have cancer and while researching I found some articles that show a link between application of 2,4,D aka weed and feed and canine cancer. If it is hurting our fur friends, it can’t be good for us either. Not to mention the deleterious environmental effects. Maybe you should talk to your neighbors about going in on a lawn service like In Harmony which uses organic methods. My neighbor used them for a while and his lawn looked great and no nasty chemicals. Maybe you could offer to maintain the fence line if they agree to stop? There must be a neighborly way to approach this. I wish you luck and sorry you have to deal with this! I am very lucky that my neighbors have just as many weeds as I do so clearly do not use chemicals.