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Beth Grafton-Cardwell
Lindcove Research and Extension Center director Beth Grafton-Cardwell looks at different varieties of citrus fruit growing in a greenhouse at the Exeter, Calif., facility.

Citrus board relies on UC scientists for critical research

As the California Citrus Research Board celebrates its 50th anniversary, it has had no closer partner than the University of California.

As the California Citrus Research Board celebrates its 50th anniversary, it has had no closer partner than the University of California.

Beth Grafton-Cardwell, director of the UC Lindcove Research and Extension Center in the foothills above Visalia, Calif., has seen lots of changes since arriving at the center in 1990. “When I first started, to estimate the yield of a tree we had to manually count the fruit,” she says. Now, citrus fruit is placed in bins that go through a packing line with a Compac fruit grading system that measures weights, sizes, shape, color, and even sugar content.

The center built a laboratory, screen houses, and a greenhouse for the industry’s Citrus Clonal Protection Program, which releases disease-free budwood to nurseries so all trees will be disease-free. When the Asian citrus psyllid brought the deadly tree disease Huanglongbing to Southern California, the center’s greenhouses had to be retrofitted to protect against the pest, Grafton-Cardwell says.

These facilities — and the critical work that goes on inside them — were largely made possible by the industry-funded California Citrus Research Board, which is observing its 50th anniversary this year. Since the 1990s, the board has given more than $2.3 million to Lindcove for facilities and has funded much of the center’s research, she notes.

While the board has numerous partners, including the state’s Citrus Pest and Disease Prevention Program and Citrus Quality Council, no partnership is greater or more crucial than the one it has built with the UC.

“It’s fabulous,” Grafton-Cardwell says of the board’s relationship with the university. “There are committees from the CRB that interact with our researchers to maximize and orient the research toward the industry’s needs.”

Often scientists tend to study things they themselves find interesting, but the CRB helps them attune their studies to realities that growers face on the ground.


The Citrus Research Board was established in 1968 to administer the industry’s research program, which includes studies on production and variety improvement, quality assurance studies on agricultural chemical residues, pest and disease control functions, and other pertinent activities.

The board is funded by an assessment collected from handlers and processors of just over 5 cents per 40-pound field box, and in turn sends money to other programs, including the UC Division of Agriculture and Natural Resources.

Among the UC’s biggest projects is the Citrus Clonal Protection Program at UC-Riverside, which was started more than 60 years ago and seeks to provide a safe mechanism for introducing new varieties from other areas of the world. The program’s roots date back to 1933 with the discovery of the citrus psorosis virus, which led to the Psorosis Freedom Program in 1937 and later evolved into the Citrus Variety Improvement Program and, finally, the CCPP, according to the program’s website.

Scientists in UCR’s Department of Plant Pathology and Microbiology work with the state Department of Food and Agriculture and the USDA Animal and Plant Health Inspection Service to diagnose diseases, eliminate pathogens, and distribute clean budwood for commercial and residential use. Led by UC Extension Specialist Georgios Vidalakis, the program has ramped up its number of varieties, Grafton-Cardwell says.

The university began its presence in Riverside in 1907, opening a research station with faculty working on citrus and other subtropical crops. Citrus research was folded in when the UC-Riverside campus was established about 50 years later, according to the UCR website.


The university’s Citrus Variety Collection, located at Lindcove, consists of two trees each of more than 1,000 different citrus types. Under the guidance of genetics chair Mikeal Roose, the Riverside campus’ breeding program has evolved from traditional breeding to cutting-edge genetic engineering, Grafton-Cardwell says.

Much of UC-Riverside’s attention — and the Citrus Research Board’s funding — is now going toward developing protections against Huanglongbing before it begins infecting commercial groves.

The importance of the emphasis was highlighted last summer when CDFA officials confirmed the discovery of HLB in a residential grapefruit tree in Riverside, just wo miles from the UCR campus. University officials have worked to prepare the campus for an HLB quarantine since shortly after the first case of Huanglongbing was found in Southern California in 2012.

Several years ago, the citrus industry raised $8 million to construct a biosecurity-level 3 laboratory near the university, enabling Vidalakis and others to do work with plant pathogens that previously had to be sent to UC-Davis or elsewhere.

The Lindcove facility at Exeter was established in 1959 on 175 acres donated to UC-Riverside, and the land was later transferred to UCANR ownership. The soils and climate of the facility, which is at 500 feet above sea level, are representative of the 200,000 acres of commercial citrus growing in California’s Central Valley, UC officials say.

Various researchers use the facility to develop new citrus rootstocks and scions, evaluate the effects of the local environment on rootstock and scion combinations, screen seedless varieties of mandarins, detect freeze damage in fruit, and analyze chemical treatments for pests and post-harvest diseases.

For instance, UC-Santa Barbara Computer Science Professor Chandra Krintz and Researcher Rich Wolski are using a plot at Lindcove to test their new digital program called SmartFarm, which uses tiny sensors to monitor the conditions of each plant and the soil around it.


Much of the center’s work has proceeded with the help of the Citrus Research Board, which donated $1.8 million for a Citrus Clonal Protection Program screenhouse and headhouse, $350,000 for a second screenhouse, $130,000 for the Compac fruit grading system, $387,000 for a positive-pressure greenhouse for the clonal program, additional money to upgrade the fruit grading system, and numerous grants for research, according to Grafton-Cardwell.

“The purpose of the center has always been to conduct research that will be representative of the San Joaquin Valley,” she says. “For decades, the Citrus Research Board has provided the facilities and grant funding to make that happen.”

As an example, the CRB funded equipment for a center laboratory built in 2008 for plant pathologists to study plant diseases. Staff Research associate Stephanie Doria got her degree at UC-Davis, but grew up in the area and wanted to return, she says. “It’s pretty interesting,” she says of work at the center. “It’s very practical — that’s the best thing. We’re producing research that actually helps people.”

There’s plenty of work to be done. New research programs at Lindcove include developing citrus varieties with tolerance to HLB, and perhaps a project to grow citrus under a screen in what is known as a Citrus Under Protective Structure, or CUPS. If built, the CUPS facility will be housed on a 10-acre section of the Lindcove center.

“We’re making slow, steady progress” against HLB, Grafton-Cardwell says. “We don’t see a silver bullet. However, that’s where the bulk of the CRB budget is going now.”

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