While National Bean Day earlier this week probably went unnoticed by many, bigger news out of the University of California says work continues on developing large and baby lima bean varieties that are more drought tolerant and resistant to pests.

California farmers produce nearly all of the nation’s lima beans, according to the University of California. About 23,000 acres of baby and large limas with a value of about $30 million were produced in 2012, according to the National Agricultural Statistics Service.

“While that’s not a lot compared to some crops in our state, it’s significant because California growers produce 60 to 80 percent of the world’s market of dry limas,” said Rachael Long, UC Cooperative Extension advisor.

The primary export market for California baby lima beans is Japan, where they are used to make Japanese confections, such as sweet bean filling for manju.

Dry lima beans, which are canned or packaged for domestic or export markets, are grown in California. Thick green lima beans for freezing are grown on the East Coast.

Among California lima beans, there are baby limas and large limas, and bush and vine types of both. Baby limas are grown primarily in the Sacramento Valley, while the large limas are grown south of Tracy and on the Central Coast. Large limas grown on the Central Coast are mostly dry farmed and used for canning.

“Lima beans are primarily grown as a single summer crop in the Sacramento and San Joaquin valleys,” said Long, who serves the counties of Yolo, Solano and Sacramento.

“Baby limas are produced in the warmer areas north and south of the Bay Delta and large limas in the south Delta area, which has a slightly longer and drier harvest season and cooler night temperatures favoring flowering and pod filling,” she said. “So there’s lots of baby limas in the Knights Landing area and large limas in the Patterson area.”

Nitrogen benefits

Farmers like to grow lima beans because they fix nitrogen, improve soil health, use relatively few pesticides and help control weeds in field crop rotations with crops including wheat, corn, tomatoes, alfalfa and sunflowers.

Because lima beans are not a widely planted crop that would attract research investment by private companies, growers depend on UC research for improved varieties.

University of California researchers including Long, Paul Gepts and Phil Roberts are continuing their work in lima bean trials.

“The lima breeding research has proven very valuable to the industry,” said Nathan Sano, manager of the California Dry Bean Advisory Board. “The two most recent baby lima varieties, UC Haskell (vine type) and UC Bejia Flor (bush type), have given growers new high-yielding varieties with some lygus resistance.” 

Lygus bugs, which feed on buds and flowers, are very destructive to lima fields.

New varieties have allowed growers to reduce pesticide use, according to Sano. Researchers are continuing their work to breed lygus-resistant traits into large lima bean varieties.

Work is also under way to breed plants that use less water.

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“We are trying to find how much we can reduce water and still get sufficient yields,” said Gepts. “Eventually we hope to test to identify markers for drought tolerance to lower the number of irrigations.”

Information on lima bean production in California can be downloaded for free at http://anrcatalog.ucdavis.edu.

The University of California also has published cost of production studies for dry beans, including baby vine and bush types: “Sample Costs to Produce Beans-Common Dry Varieties Double Cropped in the Sacramento Valley” and “Sample Costs to Produce Beans-Common Dry Varieties-Single Cropped in the Sacramento Valley.”

The production cost studies can be downloaded for free at http://coststudies.ucdavis.edu.