For many years the University of California has been conducting alfalfa variety trials at its field stations in several locations throughout the state. While none of these are in Stanislaus County, there are several field stations in the Central Valley. The field station on the Davis campus just west of Sacramento is on excellent loam or clay loam soil. Their climate is just a little cooler and wetter than here. The Kearney Agricultural Center is located near Parlier, just south of Fresno. The soils there tend to be sandy loams, similar to the east side of Stanislaus County. The climate is hotter and somewhat drier than here. The Westside Field Station is located at Five Points and isn't near anywhere. It is on the westside of Fresno county, southwest of Fresno and northwest of Hanford. The soils there are heavier, and the climate is hotter and drier.
These are small plot trials with each variety replicated four times. All cuttings are taken. Trials are left in as long as the stand remains good. In addition to the yield data, the percent cover information is useful because it gives some indication as to how well that variety is persisting. Be careful comparing varieties in a trial that is only a year or two old. If you look at the yearly data from the older trials, you can see that some varieties that looked great in the first year or so really went downhill later in the life of the stand.
Because alfalfa seed companies choose what varieties they wish to include in the trials, there are always many experimental varieties. For the sakeof clarity, I have not included these in the summaries. Unfortunately, some companies did not submit all their commercially available varieties,so there is no data available for them.
Each year the Certified Seed Council publishes information on all the commercial varieties sold in the United States. The companies supply the resistance ratings listed for the various pests according to standards set by the industry. Since varietal resistance is often the only means of controlling most pests, choose a variety that is resistant to the pests and diseases you are expecting in your field. On the westside, high levels of resistance to phytopthora root rot and stem nematode are essential. On the eastside, root knot nematode and aphid resistance might be more important. Finding out what caused your previous stands to go out will help you decide what to look for in pest resistance. Extra seed cost is easily recovered when you invest in a variety that will give you more yield and better stand life.
November 5, 1999