Posts Tagged: UC Davis

Asian citrus psyllid study: Vigilance urged but ‘no cause for panic’

Preliminary results indicate 3.5% of ACP collected showed signs of bacterium that can cause huanglongbing

An ongoing study in the commercial citrus groves of coastal Southern California is looking at whether Asian citrus psyllids – the insect vector of huanglongbing “citrus greening” disease – are carrying the bacterium that can cause HLB.

Thus far, the project has tested more than 3,000 adult ACP collected from 15 commercial citrus sites across the region, of which 138 – just over 3.5% – had some level of the bacterium present, according to researchers from UC Agriculture and Natural Resources, UC Davis, UC Riverside and the University of Arizona, Tucson.

“While the results are a cause for concern, the situation in California is much better than in Florida and Texas, where ACP carrying the bacterium make up the majority of the population and HLB is widespread in commercial citrus,” said Neil McRoberts, a UC Davis plant pathologist and UC Integrated Pest Management program affiliate advisor. “The results indicate that there is no room for complacency, but also no cause for panic.”

Since the first HLB-infected tree in California was found in 2012, nearly 4,000 infected trees have been detected and removed from residential properties in Southern California, mainly in Orange and Los Angeles counties. According to McRoberts, “to date, no HLB has been found in commercial citrus” in California.

He stressed, however, that the aforementioned ACP study – funded by the HLB Multi Agency Coordination Group and managed by USDA-APHIS – does not involve any testing of trees for HLB and focuses only on looking at the insect which spreads the bacterium.

McRoberts also emphasized that the project's detections of the bacterium cannot be considered “official” because the researchers' lab procedures differ from the official testing protocols of the California Department of Food and Agriculture.

“Follow-up sampling by CDFA staff would allow official samples to be collected for further investigation, but is entirely voluntary for the growers involved,” he said, adding that his research team is currently wrapping up the sampling phase of the project, with data analysis continuing into 2023.

While commending the “huge coordinated effort” by the California citrus industry, California Department of Food and Agriculture, UC ANR and other partners to suppress the ACP vector and slow the spread of HLB, McRoberts also urged continued vigilance.

“Our study results indicate that it is not time to declare the emergency status for ACP/HLB in California over – the situation is still evolving,” he said.

For further information about the research, contact Neil McRoberts at nmcroberts@ucdavis.edu or (530) 752-3248.

UC Davis awarded grant to advance strawberry breeding, genetic tools

The $6.2 million grant centers on protecting crops in the future

The federal government is awarding $6.2 million to University of California, Davis, to study how to use breeding and genetic information to protect strawberry crops from future diseases and pests.

The four-year grant from the National Institute of Food and Agriculture (NIFA) centers on addressing expanding and emerging threats to strawberries, a popular fruit packed with Vitamin C and key to the diets of many Americans.

Enhanced plant breeding, gene editing and other technologies will be key to ensuring strawberry crops are sustainable in the face of climate change and possible restrictions on chemical use, said Steve Knapp, director of the Strawberry Breeding Center and a distinguished professor in the Department of Plant Sciences.

“We need to have the technology so that we can deal with the challenges strawberries face around the world,” Knapp said. “Can we use genetic knowledge to change the DNA in a specific way to get the resistance we need?”

USDA funding

The grant award was one of 25 announced Oct. 5 by NIFA – an agency of the U.S. Department of Agriculture – as part of the Specialty Crop Research Initiative program, which addresses “key challenges of national, regional and multistate importance in sustaining all components of food and agriculture…,” the agency said.

The strawberry industry has lagged behind crops like tomato and wheat when it comes to genetic and technical innovation, Knapp said, and the grant signifies that “now they want the foot on the accelerator.”

A key priority is identifying whether changing DNA molecules can improve disease resistance and what technologies would be needed. Ensuring some genes are expressed while others are suppressed would be part of the analysis.

“We're trying to build in natural resistance to pathogens through the genes that already exist but could be modified with this knowledge,” Knapp said. “If we were able to edit a gene that improves disease resistance, people would want us to use that in breeding.”

The intent is to produce disease-resistant cultivars and identify better ways to diagnose, prevent and manage disease. The research project will also include an economic forecast evaluating the consequences of production changes and communicating with farmers about the laboratory advances, according to the grant proposal.

Gitta Coaker from plant pathology and Mitchell Feldmann, Marta Bjornson and Juan Debernardi from plant sciences are participating in the research, as are scientists from California Polytechnic State University, UC Agriculture and Natural Resources, UC Berkeley, University of Florida and USDA's Agricultural Research Service.

Agave: The new drought-tolerant California crop?

UC Davis to study agave sustainability as tequila, mezcal industry grows

Agriculture in California faces an uncertain future as drought, wildfires and other climate extremes become more commonplace in the West. But a fledgling industry focused on growing and distilling agave plants, which are used to produce tequila and mezcal in Mexico, could be California's answer to fallowed fields and a lack of water.

Earlier this year a group of growers, distillers and retailers formed the California Agave Council to foster collaboration and offer a chance to share knowledge among members who previously had no formal network.

Now, the University of California, Davis, has established the Stuart & Lisa Woolf Fund for Agave Research to focus on outreach and research into the plants and their viability as a low-water crop in the state.

“The rainfall patterns and growing conditions in California are different from those where tequila is made,” said Ron Runnebaum, an assistant professor of viticulture and enology. “It is exciting to begin to harness the capabilities at UC Davis to determine which agave varieties can be grown commercially in California and what flavors can be captured by distillation to make unique California agave spirits.”

The fund was created with a $100,000 seed gift from Stuart and Lisa Woolf, who are Central Valley farmers and have a test plot of about 900 agave plants on 1.5 acres. They hope this gift will encourage others to also contribute.  

The gift is focused primarily on optimizing production in California relative to Mexico, where labor costs are lower, and the farmers rely on rain rather than irrigation for water.  Stuart Woolf believes California producers could grow larger plants with higher sugar content.

“I really believe we could be very competitive with Mexico,” he said.

The research also offers a chance to better understand the impact of location on the growth of the plant, which can be a source of fiber and alternative sweetener as well as the distilled spirits it can produce.

“As a drought-tolerant plant, agave holds great potential in water-stressed California,” Woolf said. “It's a crop that could get by with little to no water during periods of extreme drought.”

A crop with low water needs

Mezcal can be made from any agave variety in Mexico while tequila, Runnebaum said, comes solely from the blue agave plant grown within the geographically defined region of “Tequila.” In California, blue agave plants can weigh 110 pounds or more, and it takes about 11 pounds of agave to produce one bottle of tequila, according to a UC Davis article published last year. The plants in Mexico weigh 50 to 60 pounds on average, Woolf said.

Agave plants require minimal watering, can serve as firebreaks from wildfires and offer a chance for farmers to plant crops on land that would otherwise have to be fallowed, or abandoned because of a lack of water. It takes roughly six to eight years for the plants to mature. 

“If we enter a severe drought, this is a crop I think we can avoid watering totally,” Woolf said. “For me, this plant is kind of coming around at the right time.”

Craig Reynolds, the California Agave Council founding director who has about 500 plants growing, says the industry is in “an embryo stage” and organizing can help the crop expand. He runs California Agave Ventures, which grows blue agave and sells starter plants to other growers.

“It's really taking off,” he said.

Coming together

About 40 growers and distillers gathered for a symposium in May to talk about the crop, from economics and logistics to site planning and processes. It ended with a tasting and sensory analysis of California products.

UC Davis hosted the event to bring people together and introduce them to what the university could offer in terms of research, training and outreach, Runnebaum said.

“I think there's a lot of promise in this potentially being a drought-tolerant crop in California,” he added. “UC Davis can help organize and research.”

The Woolfs would like their gift to be used to answer early research questions about growing sites, plant attributes and possible funding agencies, as well as gathering harvest data and producing a database with that information, according to the gift agreement. 

Some key questions to answer: Is frost risk in California too high in relation to Mexico, where the plants thrive? Can California produce a fast-growing, high-sugar, disease-resistant crop?

In addition to creating best agricultural practices for the crop and doing economic analysis, UC Davis could serve as a training ground, much as it does for brewing and winemaking.

“UC Davis also has the potential to train future leaders for this industry,” Stuart Woolf said.

Editor's note: Runnebaum is affiliated with UC Agriculture and Natural Resources through the Agricultural Experiment Station at UC Davis.

Growing cereal crops with less fertilizer

Discovery could reduce nitrogen pollution, save farmers billions

Researchers at the University of California, Davis, have found a way to reduce the amount of nitrogen fertilizers needed to grow cereal crops. The discovery could save farmers in the United States billions of dollars annually in fertilizer costs while also benefiting the environment.

The research comes out of the lab of Eduardo Blumwald, a distinguished professor of plant sciences, who has found a new pathway for cereals to capture the nitrogen they need to grow.

The discovery could also help the environment by reducing nitrogen pollution, which can lead to contaminated water resources, increased greenhouse gas emissions and human health issues. The study was published in the journal Plant Biotechnology.

Nitrogen is key to plant growth, and agricultural operations depend on chemical fertilizers to increase productivity. But much of what is applied is lost, leaching into soils and groundwater. Blumwald's research could create a sustainable alternative.

“Nitrogen fertilizers are very, very expensive,” Blumwald said. “Anything you can do to eliminate that cost is important. The problem is money on one side, but there are also the harmful effects of nitrogen on the environment.”

A new pathway to natural fertilizer

Blumwald's research centers on increasing the conversion of nitrogen gas in the air into ammonium by soil bacteria — a process known as nitrogen fixation.

Legumes such as peanuts and soybeans have root nodules that can use nitrogen-fixing bacteria to provide ammonium to the plants. Cereal plants like rice and wheat don't have that capability and must rely on taking in inorganic nitrogen, such as ammonia and nitrate, from fertilizers in the soil.

“If a plant can produce chemicals that make soil bacteria fix atmospheric nitrogen gas, we could modify the plants to produce more of these chemicals,” Blumwald said. “These chemicals will induce soil bacterial nitrogen fixation and the plants will use the ammonium formed, reducing the amount of fertilizer used.”

Blumwald's team used chemical screening and genomics to identify compounds in rice plants that enhanced the nitrogen-fixing activity of the bacteria.

Then they identified the pathways generating the chemicals and used gene editing technology to increase the production of compounds that stimulated the formation of biofilms. Those biofilms contain bacteria that enhanced nitrogen conversion. As a result, nitrogen-fixing activity of the bacteria increased, as did the amount of ammonium in the soil for the plants.

“Plants are incredible chemical factories,” he said. “What this could do is provide a sustainable alternative agricultural practice that reduces the use of excessive nitrogen fertilizers.”

The pathway could also be used by other plants. A patent application on the technique has been filed by the University of California and is pending.

Dawei Yan, Hiromi Tajima, Howard-Yana Shapiro, Reedmond Fong and Javier Ottaviani from UC Davis contributed to the research paper, as did Lauren Cline from Bayer Crop Science. Ottaviani is also a research associate at Mars Edge.

The research was funded by the Will W. Lester Endowment. Bayer Crop Science is supporting further research on the topic.

Editor's note: Blumwald is affiliated with UC Agriculture and Natural Resources through the Agricultural Experiment Station at UC Davis.

UC Davis to build new $5.25M greenhouse to protect U.S. grapevine collection

Project designed to prevent red blotch and other grapevine diseases

A new, $5.25 million greenhouse is being built on the University of California, Davis, campus to safeguard an important grapevine collection from red blotch disease and other pathogens. 

The 14,400-square-foot greenhouse will have a vestibuled entry, be insect-proof and provide another level of disease protection. It is being spearheaded by Foundation Plant Services, or FPS, which provides the U.S. grape industry with high-quality, virus-tested grapevine plant material.

The program serves as the primary source for grapevine plant material distributed to nurseries under the California Department of Agriculture's Grapevine Registration and Certification Program, which provides the majority of grapevines planted in the United States. For the grape industry, it is essential to protect this material from disease-carrying insects and guarantee fast access to clean plant material.

“The program is considered the largest quarantine center for the grapevine industry in the United States,” said Maher Al Rwahnih, a plant pathologist and FPS director. “This is kind of a game changer for us.”

A history of serving the grapevine industry

FPS has maintained healthy grapevine planting stock on the UC Davis campus for more than 70 years in open fields at the Classic and Russell Ranch foundation vineyards. FPS scientists first detected grapevine red blotch virus at Russell Ranch in 2017. By 2021, an estimated 51.6% of the crop there was infected. Material from that vineyard is not being sold, and the site is now part of an epidemiological study to try to pinpoint how the disease is transmitted.

FPS pathologists have detected red blotch on less than 1% of the Classic vineyard crop. But it may not always be that way in the future.

“We don't know how long the Classic vineyard will remain clean,” Al Rwahnih said. “Every testing season, this is what keeps me up at night. We're not sure why it's happening in Russell Ranch and not the Classic vineyard.”

Once the greenhouse is operating, grapevines propagated from plant material from the Classic vineyard will be moved into the greenhouse, tested and verified as clean from disease. From there it will be sold to nurseries, which will grow additional plants to sell to growers.

Two greenhouses part of plan

Normally the foundation has 4,000 vines available, but the greenhouse will only house 2,000 vines, so inventory will be cut in half.

“This phase is just a starting phase,” Al Rwahnih said. “It's not sufficient for our needs.”

FPS plans to build another greenhouse in the next two to three years to increase capacity.

Industry groups and FPS identified greenhouses as the best way to protect the plants from red blotch and other pathogens transmitted by insects. They are also consulting with those same people on the grape varieties to include in the greenhouse.

“We have a large selection, and we need to make sure all the varieties that are important to industry are contained,” he said.

The first greenhouse is expected to be finished by the end of 2023.

Funding for the first greenhouse is coming from a variety of sources. The California Fruit Tree, Nut Tree and Grapevine Improvement Advisory Board, managed by the California Department of Food and Agriculture, contributed $4 million to the project. The California Grape Rootstock Research Foundation gave $500,000, Foundation Plant Services with UC Davis is funding $450,000, and the California Grape Rootstock Commission gave $100,000.

“This is crucial for the grapevine industry, and we are very grateful for the support,” Al Rwahnih said.

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