WL 504
1. Phenotypic recurrent selection commenced in 1960 at Bakersfield, California, on spotted alfalfa aphid screened, nondormant selections, and/or progenies of the following: Nondormant varieties - Sirsa #9, Cal Common 49, Moapa, and African; dormant varieties - Atlantic, Vernal, Ranger, Buffalo, Williamsburg, and Lahontan; P.I. numbers - 183,262, 192,239, 201,864, 213,005, 226,518, and 231,768. From 1,000 to 3,000 seedlings resistant to spotted alfalfa aphids, pea aphids, and apparent diseases were transplanted annually in an isolated nursery. Subsequent roguing for type and suscepsibility to insects and disease reduced the population by 90% and the remaining 10% was then allowed to interpollinate. Seed of the selected survivors was harvested and recycled. WL 504 resulted from 92 selections made during the fifth cycle in 1964.
2. WL 504 is adapted to the Southwestern U.S. It has been tested in California, Arizona, New Mexico, and southern Nevada for production of hay, silage (greenchop), and dehydration.
3. Purple to light purple flowers, moderately uniform growth habit. Fall and winter dormancy - January 17, 1967, height of WL 504 - 5.8", Moapa - 5.5", Caliverde 65 - 3.5", and Washoe - 2.5" at Bakersfield, California. Upright growth, and tightly curled seed pods.
4. Two grams of seed of each of the 92 plants selected was composited and planted in isolation to produce breeder seed in Kern County, California. Sixty-five (65) pounds of breeder seed is maintained in a sealed vault. Foundation seed is the first generation seed harvested from fields planted with breeder seed in the San Joaquin Valley, California. Certified seed is that which is produced on fields planted with either breeder or foundation seed. No other class or generation will qualify for certified seed.
5. 1971.