To the question, “Which alfalfa variety should I plant?” Shannon Mueller unfurls a colorful multi-fold pamphlet listing an alphabet soup of more than 250 alfalfa varieties sold in California, and facetiously says, “Pick one.”

The University of California Cooperative Extension agronomy farm advisor for Fresno County used this to admit that selecting an alfalfa variety for a new stand can seem like a daunting task.

It need not be, Mueller told growers and others at an alfalfa and forage field day at the UC Kearney Research and Extension Center in Parlier, Calif.

You start with selecting varieties with dormancy ratings that fit your geographic location. Varieties are rated by numbers 1-11. These numbers identify a variety’s growth habits in the fall in response to decreasing temperatures and day length. Fall dormancy influences stand persistence, adaptation, and performance. The lower the number, the less growth in the fall and more winter hardiness in a variety.

Since the Central Valley winter weather would not kill a stand of alfalfa, varieties with dormancy ratings of 7, 8 or 9 fit in the San Joaquin Valley.

Ferreting out correct dormancy varieties for your area should narrow the choices to perhaps 50 from a list of 250. Breaking them down by yield using variety trials from UC, crop consultants or seed companies likely will reduce the possibilities to 10 to 15.

“Look at the top third in yield in trials for your area,” to reach that list of options, she says, adding it is good to evaluate results over several years since an alfalfa stand will persist for three or more years in a hot climate. It will persist far longer than that in the intermountain regions of the state.

Alfalfas are bred for pest tolerance. Be aware of potential pests in your alfalfa to select the right resistance trait, she suggests. Stand persistence is another evaluation point.

Alfalfa hay quality is a big issue with as many opinions as to what makes quality as there are varieties. It can be variety specific, but Mueller believes crop management (irrigation, cutting schedule and fertilization) has more influence on quality than the variety.

When the selections for new stands have been made, plant small test plots to evaluate your selections on your own farm, she says.

And don’t cut corners on seed cost. Spending $50 per acre more for certified, quality seed could return $500 per acre more in income over the life of a stand. That extra for seed “could be money well-spent,” she says.

Ideal planting window

There is the persistent question as to when to plant. UC forage specialist Dan Putnam learned at Kearney that the UC recommendations developed more than 20 years ago by his predecessor Vern Marble are still very valid.

It was in a certified organic alfalfa trial at Kearney that Putnam once again validated UC’s long standing recommendations.

Sixty to 80 percent of the success of an alfalfa crop occurs at stand establishment. This is more critical in organic alfalfa, due to the threat of weeds killing a stand. Putnam’s small trial had plenty of those, he said. The field was fallowed over the summer and tilled to control summer weeds.

A Sept. 23 planting date provided the highest first yields (10 tons per acre in four harvests) in the first season. An early spring (March 12) planting was the second most successful and “would be a good second choice if early fall planting was not feasible,” says Putnam.

A Dec. 9 seeding date was a disaster. This time frame is often used by growers to catch seasonal rains. It did not rain on the Putnam plots and the field had to be irrigated. It failed nevertheless, due not only to the lack of rain, but weeds and cold temperatures at stand establishment.

The late spring planting (April 24) was successful with fewer weeds, but yields were approximately half of the fall planting date.

Clipping in the fall-planted plots was beneficial in controlling winter weeds. “We clipped twice only the top one-third of the canopy to prevent windrows from smothering the crop from excessive herbage.”

An oat companion crop with the alfalfa was not “particularly effective preventing weeds,” Putnam reports.

Summer weeds like lambsquarter, pigweed and watergrass can be “extremely problematic” in organic or conventional stands of alfalfa.

“A vigorous alfalfa stand is the best defense against weeds,” Putnam emphasizes.

Alfalfa fertility

Alfalfa needs phosphorous and potassium to thrive and growers should establish benchmarks in fields to determine if there are deficiencies in those nutrients, according to Michelle Leinfelder-Miles, UCCE Delta crops advisor based in San Joaquin County.

She recommends taking 15 to 20 core samples from the top 6 to 8 inches of soil. Sampling at field establishment is usually sufficient to evaluate nutrient needs, she says.

Collect 40 to 60 stems from at least 30 plants for a tissue benchmark. Best time to sample stems is at one-tenth bloom before first cutting.

For alfalfa fertility guidelines, go to http://alfalfa.ucdavis.edu/.

Leinfelder-Miles recommended using granulator 0-45-0, 11-52-0) or liquid (10-34-0) to correct P deficiency. Use muriate of potash (0-0-52) to correct K deficiency, she adds.

Alfalfa weevils

Alfalfa weevils are now producing four generations per season in the San Joaquin Valley and are impacting several cuttings, according to UC IPM specialist Pete Goodell.

There are three different weevil species in California that at one time only impacted early cuttings.

It is mostly the Egyptian Alfalfa Weevil (EAW) that impacts the state’s largest acreage.

Goodell said little weevil research has been conducted of late, and it is needed since the EAW has been more prevalent in heavy populations in several areas of the valley, including Firebaugh and Dos Palos.

Goodell believes the increasing populations are the result of limited biological control and resistance to older pesticides.

Even if control is 80 percent, that means 20 percent remain in the fields. With the higher prices of hay, that represents a significant loss of income, says Goodell, who promised to renew research on the weevil.

Forage sorghums

The dwindling agricultural water supply and economically struggling dairy industry has prompted an interest in producing forage sorghums rather than corn silage.

According to UC agronomist Bob Hutmacher, Tulare County UCCE farm advisor and Jeff Dahlberg, director at the Kearney center, research elsewhere has shown forage sorghums utilize half to a third of the water of corn forage and still provide excellent nutritional feed for animals.

This has prompted several variety trials at Kearney and the Westside Research and Extension Center at Five Points, Calif.

Fourteen seed companies have provided 80 hybrids for the trials funded by the United Sorghum Checkoff Program.

These California trials are validating the results of similar research in Texas. “Given the limited amount of irrigation used in these (California) studies, low inputs and high yield, the potential does exist to save water and fertilizer” with these forage sorghums.

However, the first year of the trials also revealed that more research is needed to identify proper planting dates, densities, fertilization and water to optimize yield without lodging issues.