Yolo
1. Yolo is an alfalfa cultivar developed by mass selecting plants in 3 and 4 year old alfalfa hay fields in southern Sacramento and northern San Joaquin Valleys in CA in 1982. The 4 fields were severely thinned and plowed soon after the selections were made. Yolo consists of 2 released varieties commonly grown in the areas where selected and a variety of unknown origin leading to the following germplasm sources: M. falcata C 1%, Ladak C 1%, M. varia 2%, Turkistan 54%, Chilean 5%, Peruvian < 1%, Indian 8%, African 22%, and 8% unknown. The plants were reselected in greenhouses in Sacramento and Woodland based on agronomic characteristics and the lack of foliage diseases, reducing the original population from 224 plants to 130. Approximately 4 cuttings of the 130 clones were planted in a screened isolation cage (83C64) and pollinated with leafcutter and honeybees to produce breeder (Syn. 1) seed. The plants were dug and transplanted in 1984 to produce 84D91.
2. Yolo should be adapted to the northern San Joaquin Valley, southern Sacramento Valley, Hemit and Antelope Valleys of California. It should also perform well at moderate elevation in Arizona. It will be used primarily for hay, greenchop, and dehydration. Yolo was tested in California.
3. Yolo is moderately non-dormant and the flowers are 99% purple with about 1% variegated and a trace of cream and white. The growth habit is erect and moderately erect in late fall. The pods are tightly coiled and tan to brown in color.
4. Yolo has high resistance to spotted alfalfa aphid, pea aphid, and Fusarium wilt; resistance to blue alfalfa aphid; moderate resistance to Phytophthora root rot and stem nematode; and low resistance to bacterial wilt and anthracnose. Its reaction to Verticillium wilt is unknown.
5. Breeder seed (Syn. 1) was produced in isolation cages in Woodland, CA, in 1983 and 1984. Foundation seed (Syn. 2) is produced in fields planted with breeder seed. Certified seed (Syn. 2 or 3) is produced from either breeder or foundation seed. The foundation and certified seed classes will be planted in the southern Sacramento or San Joaquin Valley of California. The stand duration will be 2, 2, and 4 years for breeder, foundation, and certified fields, respectively. No other class or generation will quality.
6. Certified seed will be available in 1981.
7. Application for Plant Variety Protection is undecided.
8. Information may be given to the PVP office.