Prodiamine on established alfalfa

Here the last two years my field of non rr alfalfa has had a strip of pig weed about 50 yards wide that comes back with every cutting. The field is getting close to needing tore up and rotated out but I'd like to see at least one more season out of it possibly two. My question is has anyone used prodiamine in the spring and had good results? If so at what rate are you mixing and applying at? Did it stunt the growth of the crop? When are you spraying? Looking to clean up the weeds and I know it has helped on my wife's landscaping, garden and even the yard and driveway. Just worried it may harm the alfalfa.

Prodiamine on established alfalfa