- Author: Olga Kuchment, Communications Specialist, Texas A&M AgriLife
- Author: Mike Hsu
UC ANR part of team led by Texas A&M AgriLife combating huanglongbing disease
Citrus greening, or huanglongbing disease (HLB), is the most devastating disease for orange and grapefruit trees in the U.S. Prevention and treatment methods have proven elusive, and a definitive cure does not exist.
Since HLB was detected in Florida in 2005, Florida's citrus production has fallen by 80%. Although there have been no HLB positive trees detected in commercial groves in California, more than 2,700 HLB positive trees have been detected on residential properties in the greater Los Angeles region.
“It is likely only a matter of time when the disease will spread to commercial fields, so our strategy in California is to try to eradicate the insect vector of the disease, Asian citrus psyllid,” said Greg Douhan, University of California Cooperative Extension citrus advisor for Tulare, Fresno and Madera counties.
Now, a public-private collaborative effort across Texas, California, Florida and Indiana will draw on prior successes in research and innovation to advance new, environmentally friendly and commercially viable control strategies for huanglongbing.
Led by scientists from Texas A&M AgriLife Research, the team includes three UC Agriculture and Natural Resources experts: Douhan; Sonia Rios, UCCE subtropical horticulture advisor for Riverside and San Diego counties; and Ben Faber, UCCE advisor for Ventura, Santa Barbara and San Luis Obispo counties.
$7 million USDA project
The $7 million, four-year AgriLife Research project is part of an $11 million suite of grants from the U.S. Department of Agriculture National Institute of Food and Agriculture, NIFA, to combat HLB. The coordinated agricultural project is also a NIFA Center of Excellence.
“Through multistate, interdisciplinary collaborations among universities, regulatory affairs consultants, state and federal agencies, and the citrus industry, we will pursue advanced testing and commercialization of promising therapies and extend outcomes to stakeholders,” said lead investigator Kranthi Mandadi, an AgriLife Research scientist at Weslaco and associate professor in the Department of Plant Pathology and Microbiology at the Texas A&M College of Agriculture and Life Sciences.
The UC ANR members of this collaboration will be responsible for sharing findings from the research with local citrus growers across Southern California, the desert region, the coastal region and the San Joaquin Valley.
“In addition to the ground-breaking research that will be taking place, this project will also help us continue to generate awareness and outreach and share the advancements taking place in the research that is currently being done to help protect California's citrus industry,” said Rios, the project's lead principal investigator in California.
Other institutions on the team include Texas A&M University-Kingsville Citrus Center, University of Florida, Southern Gardens Citrus, Purdue University and USDA Agricultural Research Service.
“This collaboration is an inspiring example of how research, industry, extension and outreach can create solutions that benefit everyone,” said Patrick J. Stover, vice chancellor of Texas A&M AgriLife, dean of the Texas A&M College of Agriculture and Life Sciences and director of Texas A&M AgriLife Research.
HLB solutions must overcome known challenges
An effective HLB treatment must avoid numerous pitfalls, Mandadi explained.
One major problem is getting a treatment to the infected inner parts of the tree. The disease-causing bacteria only infect a network of cells called the phloem, which distributes nutrients throughout a tree. Starved of nutrients, infected trees bear low-quality fruits and have shortened lifespans.
Treatments must reach the phloem to kill the bacteria. So, spraying treatments on leaves has little chance of success because citrus leaves' waxy coating usually prevents the treatments from penetrating.
Second, while the bacteria thrive in phloem, they do not grow in a petri dish. Until recently, scientists wishing to test treatments could only do so in living trees, in a slow and laborious process.
Third, orange and grapefruit trees are quite susceptible to the disease-causing bacteria and do not build immunity on their own. Strict quarantines are in place. Treatments must be tested in groves that are already infected.
Two types of potential HLB therapies will be tested using novel technologies
The teams will be working to advance two main types of treatment, employing technologies they've developed in the past to overcome the problems mentioned above.
First, a few years ago, Mandadi and his colleagues discovered a way to propagate the HLB-causing bacteria in the lab. This method involves growing the bacteria in tiny, root-like structures developed from infected trees. The team will use this so-called “hairy roots” method to screen treatments much faster than would be possible in citrus trees.
“Even though a particular peptide may have efficacy in the lab, we won't know if it will be expressed in sufficient levels in a tree and for enough time to kill the bacteria,” Mandadi said. “Viruses are smart, and sometimes they throw the peptide out. Field trials are crucial.”
The second type of treatment to undergo testing is synthetic or naturally occurring small molecules that may kill HLB-causing bacteria. Again, Mandadi's team will screen the molecules in hairy roots. A multistate team will further test the efficacy of the most promising molecules by injecting them into trunks of infected trees in the field.
A feasible HLB treatment is effective and profitable
Another hurdle to overcome is ensuring that growers and consumers accept the products the team develops.
“We have to convince producers that the use of therapies is profitable and consumers that the fruit from treated trees would be safe to eat,” Mandadi said.
Therefore, a multistate economics and marketing team will conduct studies to determine the extent of economic benefits to citrus growers. In addition, a multistate extension and outreach team will use diverse outlets to disseminate project information to stakeholders. This team will also survey growers to gauge how likely they are to try the treatments.
“The research team will be informed by those surveys,” Mandadi said. “We will also engage a project advisory board of representatives from academia, universities, state and federal agencies, industry, and growers. While we are doing the science, the advisory board will provide guidance on both the technical and practical aspects of the project.”
Project team members:
—Kranthi Mandadi, Texas A&M AgriLife Research.
—Mike Irey, Southern Gardens Citrus, Florida.
—Choaa El-Mohtar, University of Florida Institute of Food and Agricultural Sciences, Citrus Research and Education Center.
—Ray Yokomi, USDA-Agricultural Research Service, Parlier, California.
—Ute Albrecht, University of Florida IFAS Southwest Florida Research and Education Center.
—Veronica Ancona, Texas A&M University-Kingsville Citrus Center.
—Freddy Ibanez-Carrasco, Texas A&M AgriLife Research, Department of Entomology, Weslaco.
—Sonia Irigoyen, AgriLife Research, Texas A&M AgriLife Research and Extension Center at Weslaco.
—Ariel Singerman, University of Florida IFAS Citrus Research and Education Center.
—Jinha Jung, Purdue University, Indiana.
—Juan Enciso, Texas A&M AgriLife Research, Department of Biological and Agricultural Engineering, Weslaco.
—Samuel Zapata, Texas A&M AgriLife Extension, Department of Agricultural Economics, Weslaco.
—Olufemi Alabi, Texas A&M AgriLife Extension, Department of Plant Pathology and Microbiology, Weslaco.
—Sonia Rios, University of California Cooperative Extension, Riverside and San Diego counties.
—Ben Faber, University of California Cooperative Extension, Ventura, Santa Barbara and San Luis Obispo counties.
—Greg Douhan, University of California Cooperative Extension, Tulare, Fresno and Madera counties.
- Author: Pamela Kan-Rice
A new study outlining the costs and returns of establishing and producing navel oranges with low-volume irrigation in the southern San Joaquin Valley has been released by UC Agriculture and Natural Resources, UC Cooperative Extension and the UC Davis Department of Agricultural and Resource Economics.
“A cost study gives a ‘new' grower a better idea of all the costs that are involved with producing the crop,” said co-author Greg Douhan, UC Cooperative Extension citrus advisor for Tulare and Fresno counties.
Real estate agents, land leasers, bankers evaluating loan applications and others can use the cost study to estimate current costs to plant and produce oranges and expected profits.
This study updates an earlier version, using as an example the Cara Cara navel, which is known for its distinctive pink-colored flesh rather than the conventional orange flesh of the Washington navel.
“The Cara Cara has been returning very good prices to growers for the past decade or so and is a relatively new navel,” said co-author Craig Kallsen, UC Cooperative Extension farm advisor in Kern County. “Of course, grower returns are driven by consumer demand. Why consumers like it so much I do not know, but I suspect it is because it tastes good and is different. You cut it and get a pink surprise. Its harvest maturity is similar to that of the Washington navel.”
The updated version takes into consideration “things like inflation, chemical availability, changes in markets both domestic and foreign, governmental regulations and other things,” Kallsen said.
The study is based on a hypothetical farm that consists of 65 contiguous acres onlandin the San Joaquin Valley previously planted to another tree crop. Establishment and production costs are based on 10 acres being planted to oranges. Mature orange trees are grown on 50 acres and the remaining five acres are roads, equipment, shop area and homestead. The grower owns and farms the orchards.
The two major orange varieties grown in the San Joaquin Valley are navels and valencias. Navels are grouped into three types by harvest timing – early, mid and late season. Due to current planting practices, only navels are included in this budget. Cara Cara is the variety of navel oranges currently most commonly planted.
The Cara Cara orange trees are planted double density, 10-by-20-foot spacing, at 218 trees per acre. At this density, it is possible to start harvesting in year 3 or 4. At year 8 or 9, full maturity is achieved and growers begin pruning back every other tree. This allows the grower to maintain yields while at the same time converting the field to 20-by-20 spacing – maximizing yield for a fully mature orchard.
For pest management, the study includes detailed information and links to UC Integrated Pest Management guidelines for citrus. The narrative contains tables of insecticide treatment cycles for establishment and production years.
The section “Exotic Pests of Economic Concern to Citrus Growers” contains information to meet quarantine regulations on exporting oranges from California to countries such as South Korea.
The authors describe the assumptions used to identify current costs for oranges establishment and production, material inputs, cash and non-cash overhead. A ranging analysis table shows profits over a range of prices and yields.
“2021 - Sample Costs to Establish an Orchard and Produce Oranges in the Southern San Joaquin Valley” can be downloaded for free from the UC Davis Department of Agricultural and Resource Economics website at coststudies.ucdavis.edu. Sample cost of production studies for many other commodities are also available for free on the website.
For additional information or an explanation of the calculations used in the studies, refer to the Assumptions section or contact Donald Stewart at (530) 752-4651, destewart@ucdavis.edu or Karen Jetter at (530) 792-8255 or jetter@ucanr.edu. To discuss this study with a UC Cooperative Extension farm advisor, contact your local UC Cooperative Extension office: http://ucanr.edu/County_Offices.
This study was funded in part by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award numbers 2017-70016-26755 and 2019-70016-29068.
- Author: Jeannette E. Warnert
Two more trees infected with huanglongbing (HLB) disease were identified and destroyed in the days before UC Cooperative Extension and the Citrus Research Board kicked off their spring Citrus Growers Education Seminar in Exeter June 27. The new infections raise the total number of HLB-infected trees in Los Angeles and Orange counties to 73.
The latest statistic set the stage for spirited discussions about a looming threat that cut Florida citrus production by 60 percent in 15 years. The devastating citrus losses in Florida were recounted by Ed Stover, a plant breeder with USDA Agricultural Research Service in Fort Pierce.
"One of the benefits of coming here is I am reminded how beautiful citrus is," Stover said. "In Florida, there are more than 130,000 acres of abandoned groves." He showed slides of trees with thin canopies, pale leaves and green fruit; in one image the trees were skeletons among tall weeds.
Huanglongbing disease is an incurable condition spread by Asian citrus psyllid (ACP). The psyllid, native of Pakistan, Afghanistan and other Asian regions, was first detected in California in 2008. Everywhere ACP is found, the pests find and spread HLB.
Stover and his colleagues are searching for citrus cultivars that have natural tolerance for the bacteria that causes HLB, but progress is slow. Transgenic citrus, he said, is the best bet for developing citrus with HLB immunity.
"In my opinion, commercial genetically engineered citrus is inevitable, and GE crop concerns will likely decline with time," he said.
In California, the aggressive push to keep psyllid populations low, regulations to limit the spread of psyllids when trucking the fruit, and active scouting for and removal of HLB infected trees in residential areas could buy time for researchers to find a solution before California suffers the fate of Florida citrus growers.
"Be vigilant," Stover said. "As long as you are still making a good return, there is almost no investment too great if it keeps HLB out of California."
Beth Grafton-Cardwell, UCCE citrus entomology specialist and director of the UC Lindcove Research and Extension Center near Exeter, said the prime research in the San Joaquin Valley is aimed at early detection techniques.
Once a tree is infected, it takes nine months to two years for the bacteria to spread throughout the tree, so that when leaves are selected for testing, they detect the bacteria. Capturing and testing psyllids is one way to to find the disease early. Other early detection techniques focus on the microbes, proteins and aromas produced by sick trees.
"These can be measured with leaf test, a VOC (volatile organic compound) sniffer, swab or even dogs," Grafton-Cardwell said. "Scientists are studying every conceivable way to stop the disease."
In the meantime, growers were encouraged to carefully monitor for and treat psyllid populations in their orchards with pesticides. Pesticide treatment recommendations are available on Grafton-Cardwell's Asian Citrus Psyllid Distribution and Management website, http://ucanr.edu/acp.
"We have lots of challenges," Grafton-Cardwell conceded. "We hate disrupting our beautiful integrated pest management program. But monitor your own groves, apply the most effective treatments and remove suspected (infected) trees. Going through the pain up front will save us in the long run."
Amanda Crump, former associate director of the Horticulture Innovation Lab at UC Davis, rejoined ANR on May 2 as director of the Western Integrated Pest Management Center.
From June 2008 to December 2009, she was a UCCE environmental horticulture advisor in Fresno County.
She left ANR to take a position at the Horticulture Innovation Lab, which builds international partnerships for fruit and vegetable research that improves livelihoods in developing countries. There, she provided programmatic leadership, managed international horticulture research projects, and worked with stakeholders, federal donors and an advisory board to identify the most pertinent horticultural research needs worldwide and to disseminate the results of this research to farmers in 19 countries.
Crump completed a B.S. in agricultural education from University of Idaho and a M.S. in plant pathology and weed science from Colorado State University. She is currently a Ph.D. candidate in agricultural education at UC Davis.
Crump is based at the ANR building in Davis and can be reached at (530) 750-1271 and acrump@ucanr.edu.
Vinchesi named vegetable advisor
Amber Vinchesi joined UCCE on April 11 as an area vegetable crops advisor for Colusa, Sutter and Yuba counties.
Prior to joining UCCE, Vinchesi was a postdoctoral research associate at Washington State University, Irrigated Agriculture Research and Extension Center, where she implemented Lygus management strategies in alfalfa seed production. She developed methods to analyze gut contents of beneficial predators to determine what predators ate when candidate insecticides reduced preferred prey numbers in alfalfa fields.
From 2014 to 2015, Vinchesi was a postdoctoral scholar at Oregon State University's Hermiston Agriculture Research and Extension Center, where her research focused on using thiamine (vitamin B1) as an alternative control method for insect-vectored potato diseases like Potato Virus Y and Zebra Chip. She also conducted pesticide trials in the greenhouse and surveyed wireworm species in the area.
As a graduate research assistant from 2009 to 2014, Vinchesi conducted research on the alkali bee, a native, solitary, soil-nesting bee used for alfalfa seed pollination in southeastern Washington. Her work included conducting environmental mitigation studies for the Department of Transportation to determine how rerouting a four-lane highway would affect populations of commercially managed native alkali bees.
Vinchesi completed a B.S. in entomology from Purdue University and both an M.S. and a Ph.D. in entomology from Washington State University.
Based in Colusa, Vinchesi can be reached at (530) 458-0575 and acvinchesi@ucanr.edu.
Greg Douhan joined ANR on March 1 as a UC Cooperative Extension area citrus advisor for Tulare, Fresno and Madera counties.
Prior to joining UCCE, Douhan had been a staff research scientist in the Department of Plant Pathology and Microbiology at UC Riverside since 2013. At UC Riverside, he was involved in virus and viroid diagnostics of citrus, studying the interaction between citrus tristeza virus and Fusarium solani (citrus quick decline disease), and conducting research on the postharvest pathogen Penicillium digitatum. At the same time, he also served as the coordinator of the National Clean Plant Network for Citrus, which has centers in California, Arizona, Texas, Louisiana, Alabama, Maryland, Florida and Puerto Rico. From 2005 to 2013, Douhan held a faculty position as assistant professor in the department.
He earned his M.S. and Ph.D. in plant pathology from Washington State University and completed a B.S. in botany/biology from Humboldt State University.
Douhan is based in Tulare and can be reached at (559) 684-3312 and gdouhan@ucanr.edu.
Tolgay Kizilelma joined ANR as the IT infrastructure and support manager on Feb. 29.
He is in charge of modernizing how ANR provides IT support services, overseeing the redesign of our technology infrastructure, and serving as a key lead in upgrading and running ANR's network infrastructure across the state.
“Tolgay has extensive experience in key technology areas such as cyber-security and technical project management,” said Gabriel Youtsey, chief information officer. “He comes to us with many years of experience running IT in both private companies and higher education.”
Kizilelma has 20-plus years of professional IT experience in the business sector, healthcare and higher education. Prior to joining ANR, Kizilelma was the IT manager at Shields Harper & Co based in Martinez, leading companywide IT initiatives for multiple locations in three states. He managed his company's U.S. operations remotely from Turkey from 2007 to 2012. During this time, he also lectured undergrad IT courses and led IT projects within the computer engineering department of Pamukkale University in Turkey.
“I am an advocate of lifelong learning, and I really would like to emphasize the effective and efficient use of resources and tools available for all ANR clients, such as Lynda.com and LMS (learning management systems) for most of our training needs,” Kizilelma said.
He earned a Ph.D. in business management at Dokuz Eylul University in Turkey, an MBA at Saint Mary's College of California and a BSc in computer engineering at Ege University in Turkey.
Kizilelma is located in the ANR building in Davis and can be reached at (530) 750-1233 and tkizilelma@ucanr.edu.
Jennifer Caron-Sale joined ANR's Office of Program Planning and Evaluation as a policy analyst on May 9. She will be assisting Katherine Webb-Martinez and Vanessa Murua with ANR strategic planning efforts and program evaluation.
Caron-Sale has been a regulatory analyst at the California Public Utilities Commission in San Francisco for the last eight years. At the CPUC, she focused on overseeing the planning, implementation and evaluation of demand response and energy efficiency programs. Prior to joining the CPUC, she taught environmental science at various non-profits in the Northeast and Midwest.
She earned a B.A. in environmental studies from Mount Holyoke College, a M.S in natural resource policy and management from the State University of New York College of Environmental Science and Forestry and a M.P.A. (public administration) from Syracuse University.
Caron-Sale is based at UCOP and can be reached at (510) 987-0214 and Jennifer.Caron-Sale@ucop.edu.
Mark Takata joined the UC Integrated Pest Management Program on Feb. 29 as a web production coordinator.
Takata has over 10 years of experience in programming, web production workflow, and user interaction/user experience design. Last year, he spent two days a week working with UC IPM as a contractor from UC Davis Information and Education Technology (IET) to help design and code the user interface for the Urban Plant Diagnostic Tool, mobile Pest Management Guideline framework and other infrastructure projects.
In the private sector, Takata consulted for UC Davis, UC Merced, Hewlett Packard, Microsoft, Avanade, HDMI, VISA and Accenture among others. In 2015, he returned to UC Davis where he provided technical solutions for the Office of the Chancellor and Provost, Mondavi Center and other campus units as an employee with IET.
For UC IPM, Takata will coordinate and ensure that IPM content is clearly laid out and efficiently published to the UC IPM website. He will also work with the rest of the IT and production staff to transition the current web pages, as well as any new projects, to a more mobile-friendly look and feel.
Takata is located at the ANR building in Davis and can be reached at (530) 750-1386 and mtakata@ucanr.edu.
Lucia Varela, UCCE area IPM advisor in the North Coast, was honored with the 2016 Pacific Branch of the Entomological Society of America's Distinguished Achievement in Extension Award.
Varela, who serves high-value wine vineyards in Napa, Sonoma, Lake and Mendocino counties, was nominated by Pete Goodell, UCCE area IPM advisor based at the Kearney Agricultural Research and Extension Center.
In his nomination letter, Goodell wrote: “The impacts from her extension program and team efforts have resulted in a reduction of insecticide use in several crops. Her work with invasive species task forces has mitigated the spread of several invasive species.”
As a specific example, he wrote, “She has taken on a major leadership role in turning back the European grapevine moth (Lobesia) infestation in the North Coast wine region by coordinating with county, state and local agencies.”
Varela received the award at the branch's annual meeting in Honolulu on April 5.
Steven Lindow, professor in the Department of Plant & Microbial Biology at UC Berkeley, has been selected to receive the Award of Distinction, the highest award made by the American Phytopathological Society in honor of his significant contributions to the science of plant pathology.
Lindow, who is also executive associate dean for the College of Natural Resources, will receive the award at the APS annual meeting in Tampa, Fla., which will be held July 30-Aug. 3.
