1. Arriba is a synthetic variety with 250 parent clones. Parent clones trace to two populations selected for resistance to verticillium wilt, anthracnose (Race 1), spotted alfalfa aphid, blue alfalfa aphid, pea aphid, and stem nematode.  Phenotypic recurrent selection was used. Final selections were made from a space - planted nursery near Nampa, Idaho.  Parentage traces to Lobo (80%) and ABI 700 (20%).  Approximate germplasm source contributions are: M. falcata (6%), Ladak (6%), M. varia (19%), Turkistan (13%), Flem