Making a hasty choice in selecting an alfalfa variety may result in three to four years of living with a stand that is performing poorly. It is worth the effort to carefully select a superior variety which will make you more profit in the long run under your conditions, even if initially the seed cost might be a little more.
The first step in selecting an alfalfa variety is to choose one that is adapted to the climate in which it will be grown. The fall dormancy rating will give you some idea of how a variety will perform based on how early it goes dormant in the fall. A dormancy rating of 1 designates a variety adapted to early, harsh freezing winters, while a rating of 9 is used for varieties with very little dormancy such as would be grown in the Imperial Valley, where it seldom freezes at all.
In Stanislaus County, there is some debate as to which dormancy varieties can be planted, however, dormancies of 7 and 8 are probably best adapted. Growers with heavy clay soils which cannot be harvested when wet usually prefer a little more dormancy than those who can ensile or green chop late fall and early spring growth. More dormant varieties are often harvested at longer cutting intervals.
Varieties that are too non-dormant for an area can make too much winter growth and may not persist. Planting a variety that is too dormant will usually decrease yields. It is not recommended to go to a dormancy 4 or 5 to obtain higher quality unless it can be determined that yield loss will not be too great.
Once acceptable dormancies have been determined, check reliable sources for information on yield performance and stand persistence. Results of trials conducted by University of California Cooperative Extension are provided in the following tables. Place the most emphasis on trials conducted under conditions most similar to your own. Choose several varieties from the highest yielding group, and cross check to make sure that they have resistance to the pests and diseases most likely to be a problem where it will be grown. Suggested minimum resistances for the San Joaquin Valley are given in table 1. Although chemical treatment is available for some of these pests, planting resistant varieties is by far the most cost-effective way of controlling them.
Only after candidate varieties have been determined to be acceptable in terms of adaptation, yield and pest resistance should quality potential be considered. A variety that has high quality but won't perform in other ways will probably not be profitable in the long run. Results from University of California trials have shown that although very dormant varieties may give higher quality, in most cases the sacrifice in yield is too great. There are differences in quality among higher yielding varieties; if quality is of prime importance to you, try to select one of these. Remember that many other management factors-- cutting schedule, weed control, proper harvest techniques, soil conditions, etc.-- will influence quality in the bale much more than varietal characteristics.
Alfalfa Variety Checklist
Thanks to Dr. Dan Putnum, UCD Alfalfa Specialist, for supplying information used in this article
November 5, 1999