Weeds in an alfalfa forage field are a symptom of problems and simply spraying with Roundup to kill the weeds will not correct the underlying problem that is causing poor performance. Forage fields of alfalfa are often planted with a companion perennial grass. Spraying an RR alfalfa field with Roundup will kill any companion grass. If the pollen from an RR alfalfa plant fertilizes the flowers on a non-RR alfalfa plant, the seed on that non RR plant will contain the RR gene, and plants that grow from that seed will be roundup resistant. This means that organic livestock will no longer be organic as GMO Alfalfa cannot be undone.