California Ag Network

Tag: HLB

  • Fresh Citrus at Risk From Devastating Disease

    Davis, Calif., (December 15, 2017) – For the first time in 70 years, California has surpassed Florida in citrus production. Florida groves have been decimated by a disease called huanglongbing (HLB), or citrus greening disease, that threatens citrus production in California, too.

    Over time, fruit of HLB-infected trees begins to turn green and develop a bitter, metallic taste. (Elizabeth Chin / UC Davis)

    “HLB is not just bad for farmers and the economy,” said Professor Carolyn Slupsky, a biochemist and nutritionist with the University of California, Davis. “The loss of fresh oranges and other citrus is a real possibility and that would seriously impact our health.”

    Slupsky and other UC Davis experts are working with farmers and fellow scientists to develop early detection methods, boost tree immunity and find a cure for the devastating disease.

    California farmers sold nearly 4 million tons of citrus in the 2016–17 marketing season, compared to 3.5 million tons from Florida, according to the U.S. Department of Agriculture. Florida produced twice as much citrus as California as recently as the 2011–12 season.

    Florida didn’t lose its top spot because the Golden State is producing more citrus. In fact, California farmers produced 14 percent fewer fresh oranges this season.

    A silent killer – Citrus greening disease is caused by a bacterium that is spread by the Asian citrus psyllid, a tiny insect that feeds on the leaves and stems of citrus trees. A tree infected with HLB can live for years without symptoms, allowing the pathogen to spread undetected to other trees. Symptoms emerge over time as a tree’s fruit starts to turn green and misshapen with a bitter, metallic taste.

    HLB is a global threat. Beyond Florida, the disease has destroyed groves in Asia, Brazil and the Dominican Republic. The disease has been spotted in about 250 backyard trees in Southern California, but so far California’s commercial orchards have been spared. Researchers are hard at work to keep it that way.

    An international team of scientists led by UC Davis chemical ecology expert Walter Leal recently identified the molecule that attracts the Asian citrus psyllid, which may help researchers develop a less toxic way to trap the insect to slow the disease’s spread.

    Slupsky is taking a different tack. She and her team are using nuclear magnetic resonance technology to study how the pathogen affects the metabolism of the tree. Her research shines a light on HLB’s mode of attack.

    “The pathogen seems to cause havoc with a tree’s ability to defend itself from infection,” Slupsky said. “That’s a spectacular discovery, because when we understand the mechanisms behind the attack we have a chance at blocking them and boosting a tree’s natural immunity.”

    Working with Kris Godfrey, an associate project scientist at the UC Davis Contained Research Facility, and Michelle Heck at Cornell University, Slupsky found differences in the chemical fingerprint of leaves starting very early in the infection process. With further research, she believes that she can develop a chemical profile to provide a reliable, rapid and early indicator of the presence of infection.

    “Early detection is key,” Slupsky said. “If we can catch the disease early in the infection and get rid of the infected trees, we can hopefully slow down the spread of HLB enough to give scientists time to find a cure.”

    Disease-resistant rootstocks – Breeders are working to develop HLB-resistant rootstock, which is one of the most promising avenues to a cure. Researchers are also looking at whether they can transform the psyllid to prevent its ability to spread HLB. UC Davis plant pathologist Bryce Falk is leading a search to find and engineer viruses that can induce traits in the insect that prevent it from transmitting the bacterium.

    Breeding rootstock and engineering viruses takes time. In the meantime, backyard citrus growers can help keep HLB at bay by monitoring their trees for signs of psyllids or infection and removing trees that are infected or near infected trees.

    How can you recognize signs of the disease? This website provides photos and tips on what to look for and how to control the pests.

    Slupsky says that together, farmers, gardeners and science can help save citrus and the nourishment it provides.

    “From a nutritional standpoint, it’s hard to beat fresh citrus,” Slupsky said. “Oranges provide energy, fiber and a wide variety of nutrients, vitamins and minerals. They’re one of the most consumed fruits in the United States. I can’t imagine life without fresh citrus.”

     

  • California Citrus Nursery Society 2017 Annual Meeting Rec

    Temecula, Calif., (November 29, 2017) – The 2017 California Citrus Nursery Society (CCNS) annual meeting was held at the Embassy Suites in Temecula, CA on November 2, 2017. CRB Associate Research Scientist, Dr. Mojtaba Mohammadi and CRB Director of Communications, Carolina Evangelo attended the meeting which was led by CCNS Executive Director, Tom Delfino. The meeting featured talks from the following speakers:

    • Bob Atkins,of the California Pest and Disease Prevention Program (CPDPP), provided an update on program outreach efforts.
    • Dan Willey, of com, delivered a proposal on how to improve quarantine labeling.
    • Chandrika Ramadugu,of UC Riverside, gave a presentation on HLB resistant rootstocks.
    • Kelsey Schall, of the Hoddle Lab at UC Riverside, discussed how better Argentine ant control in citrus groves can result in improved ACP control by Tamarixia radiata, a parasitic wasp.
    • Frank Byrne, of UC Riverside, gave an update on ACP management in retail nursery stocks through neonicotinoid use.

    A Panel Discussion on the effects of the new HLB Quarantine Zone on UC Riverside was a highlight of the meeting. Panel participants included Dr. Tracy Kahn, Dr. Peggy Mauk, Dr. MaryLou Polek, Dr. Mike Roose and Dr. Georgios Vidalakis.

    The meeting concluded with a banquet and speech by Dr. Mike Roose highlighting the genetic relationships between citrus species.

    On Friday, November 3, a group of meeting attendees headed to UC Riverside where Dr. MaryLou Polek, led a tour of the USDA-ARS National Clonal Germplasm Repository for Citrus & Dates. Drs. Tracy Kahn and Mike Roose followed up with a tour of the Citrus Variety Collection (CVC) at UC Riverside. Dr. Chandrika Ramadugu led participants on a tour of ongoing field trials evaluating the horticultural traits of hybrid citrus trees developed for HLB resistance. After lunch, participants traveled to the Citrus Clonal Protection Program’s Rubidoux facility in Riverside.  Dr. Georgios Vidalakis, the CCPP director, gave a presentation on the history of CCPP including its mission and ongoing research activities.

  • Karen Ross To Headline California Citrus Conference

    Visalia, Calif., (October 10, 2017) – The California Citrus Conference, scheduled for October 11, will feature California Department of Food and Agriculture (CDFA) Secretary Karen Ross as its keynote speaker.

    All those associated with the California citrus industry are invited to attend the free one-day event of presentations and demonstrations sponsored by the Citrus Research Board (CRB) at the Wyndham Hotel in Visalia, California. The conference will share the “best of the best” in research developments, according to CRB President Gary Schulz, and will emphasize work being done to combat huanglongbing (HLB).

    “HLB, which has decimated the citrus industry in other growing regions throughout the world, has now been found in over 150 residential trees in California,” said Schulz. “Secretary Ross will convey to growers that the CDFA understands the urgency of finding a cure for this devastating disease and stands foursquare behind the CRB’s wide-reaching research efforts.”

    “This disease is fatal to citrus trees,” Ross said. “It has no cure, so the solution must come from research – research that is already well underway, thanks to foresight and funding from growers and our state and federal leaders.”

    Ross has served as CDFA Secretary for nearly seven years. She previously was chief of staff for U.S. Agriculture Secretary Tom Vilsack and also had been president of the California Association of Winegrape Growers and vice-president of the Agricultural Council of California. Under her stewardship, the CDFA has worked diligently to track, contain and slow the spread of Asian citrus psyllids (ACP) and HLB by setting traps, treating trees in infested areas and removing HLB-positive trees.

    Other featured topics and speakers at the conference will include:

    • “The Very Latest in ACP and HLB Treatment Strategies and Detection Challenges” presented by Beth Grafton-Cardwell, Ph.D., director of the Lindcove Research and Extension Center and research entomologist, University of California, Riverside, and Carla Thomas, plant pathologist and epidemiologist, University of California, Davis.
    • “Exploration and Exploitation of the Microbial Communities That Associate with Citrus Trees” presented by Johan Leveau, Ph.D., professor of plant pathology, University of California, Davis.
    • “Improving Nitrogen Management of Citrus” presented by Steve Petrie, Ph.D., of Yara North America Inc.
    • “Being Active Is Not Being Bold” presented by Joel Nelsen, president of California Citrus Mutual.
    • “An Update from the Citrus Pest and Disease Prevention Committee (CPDPC)” presented by Nick Hill, CPDPC chairman.
    • “Priority Post-Harvest Research to Control Insect Pests of California Citrus” presented by Spencer Walse, Ph.D., research chemist with the U.S. Department of Agriculture (USDA)-Agricultural Research Service, San Joaquin Valley Agricultural Sciences Center.
    • “Panel Discussion: Biological Control Program for Asian Citrus Psyllid in California and Arizona” presented by Greg Simmons, Ph.D., entomologist with USDA-Animal and Plant Health Inspection Service, David Morgan, Ph.D., biocontrol specialist with CDFA and Richard Stouthamer, Ph.D., entomologist with the University of California, Riverside.
    • “Citrus Breeding for California: New Tools to Meet the Challenge of HLB” presented by Mikeal Roose, Ph.D., professor of genetics at the University of California, Riverside.
    • “Streamlining the Introduction of Citrus Varieties from HLB-infested Areas into California. A Case Study – Florida” presented by Georgios Vidalakis, Ph.D., professor and UC extension specialist in plant pathology, University of California, Riverside and director of the Citrus Clonal Protection Program.

    The event also will feature scientific poster presentations, networking opportunities and continuing education units, which have been approved by the Department of Pesticide Regulation.

    A complimentary breakfast buffet will be served from 6:30-9:00 a.m. Morning conference sessions are scheduled from 9:00 a.m.-noon, and will be highlighted by the keynote address from Secretary Ross. Following a free luncheon, afternoon sessions will run from 1:15-5:00 p.m.

    To register or request additional details, contact the CRB on line at www.citrusresearch.org  or by phone at 559.738.0246.

    Additionally, a special session, “Train the Trainer: Best Practices for Citrus Field Crews to Prevent the Spread of ACP/HLB” will be conducted in Spanish only from 7:00-9:00 a.m. Pre-registration for this seminar is required through www.citrusinsider.org or by phone at 559-592-3790.

  • How to Check Your Citrus Trees for a Deadly Disease and the Pest that Spreads It

    Riverside, Calif., (August 4, 2017) – The incurable citrus tree disease huanglongbing, or HLB, has been detected in Los Angeles and Orange counties and most recently in Riverside. The citrus disease is spread from tree to tree by Asian citrus psyllids, the insects that move the bacteria that cause huanglongbing.

    There is no known treatment for huanglongbing, which kills citrus trees.

    Citrus trees infected with huanglongbing develop mottled leaves and produce fruit that is misshapen, stays green and tastes bitter. There is no known treatment for the disease, which usually kills the tree within three to five years, according to UC Cooperative Extension specialist Beth Grafton-Cardwell.

    Huanglongbing, which is also known as citrus greening, has already devastated the citrus industries in Florida, Georgia, Louisiana, South Carolina and Texas.

    You can help prevent this disease from destroying California’s citrus as well as your own trees.

    Look for yellowed leaves on citrus trees. Nutritional deficiencies can also cause citrus trees to have yellow leaves so it is important to know the difference. Nutrient deficiency causes a similar pattern of yellowing on both sides of the leaf. HLB causes blotchy yellow mottling and is not the same on both sides of the leaf.

    To identify the Asian citrus psyllid and the disease symptoms of HLB, see the fact sheets, videos in English and Spanish and other resources at http://ucanr.edu/acp.

    If you see any trees that display symptoms of huanglongbing, contact your local agriculture commissioner.

    To learn about the latest research, visit UC ANR’s new Science for Citrus Health website at http://ucanr.edu/sites/scienceforcitrushealth.

    More resources on Asian citrus psyllids and huanglongbing:

  • HLB Detected on Residential Property in Riverside

    The California Department of Food and Agriculture (CDFA) and the United States Department of Agriculture (USDA) have confirmed the detection of the citrus disease known as Huanglongbing (HLB), or citrus greening, in Riverside County. The disease was detected in plant material taken from a grapefruit tree in a residential neighborhood in the city of Riverside near I-215.

    The infected tree has been removed and agriculture officials are moving swiftly on mandatory surveying in an 800-meter area. Mandatory treatments will soon follow. CDFA staff will visit all regulated entities in the quarantine area, including retail and production nurseries and packinghouses. Additionally, local, state and federal agriculture authorities are working together to determine potential implications to the University of California, Riverside, which will fall within the 5-mile quarantine area.

    Riverside County Agricultural Commissioner/Sealer Ruben Arroyo plans to take an aggressive stance on any abandoned groves in the area, and the Citrus Pest & Disease Prevention Program outreach team is already working with the City of Riverside to inform residents of the actions needed to stop HLB’s spread.

    Learn more in the press release shared by Riverside County.

  • Agricultural Officials Taking Steps to Battle Citrus Disease Recently Detected in Riverside

    Riverside, Calif., (July 27, 2017) – State and federal officials yesterday (7/25) confirmed the presence in Riverside County of citrus greening, a deadly disease for citrus plants that can be transmitted from tree to tree by the Asian citrus psyllid.

    The California Department of Food and Agriculture (CDFA) and the United States Department of Agriculture (USDA) confirmed the discovery of citrus greening, known as huanglongbing or HLB. The disease was detected in a CDFA sample collected July 10 from a grapefruit tree in a residential neighborhood in the city of Riverside, near the intersection of Chicago and Marlborough avenues. The disease affects citrus and closely related species.

    In cooperation with the Riverside County Agricultural Commissioner’s Office and USDA, CDFA has begun an extensive survey and treatment program. Crews will remove and dispose of the infected tree and are preparing to treat citrus trees within 800 feet for Asian citrus psyllid infestations. Taking these steps will remove a critical reservoir of the disease and vectors that can spread the disease, an essential tactic in protecting nearby citrus.

    The bacterial disease attacks plants’ vascular system but does not pose a threat to humans or animals. The Asian citrus psyllid can spread the bacteria when the pest moves from one location to another, feeding on citrus trees and other plants. Once a tree is infected there is no cure and it typically declines and dies within a few years.

    “The discovery of this disease means all citrus trees are at risk — including homegrown trees enjoyed by residents and thousands of acres of trees cared-for by citrus farmers,” said Ruben Arroyo, Riverside County Agricultural Commissioner/Sealer. “It’s important for residents, growers and agricultural officials to work together to quickly find this disease and stop its spread. I encourage everyone to visit CaliforniaCitrusThreat.org to review symptoms of the disease and report disease sightings.”

    A quarantine will be established in the area where HLB was detected. The quarantine prohibits the sale of all host nursery stock and the movement of all host plants and fruits within a five-mile radius of the find, and applies to residents and commercial operations alike.

    Riverside has a storied history of citrus production and is home to California Citrus State Historic Park, which preserves the cultural landscape of the citrus industry and tells the story of the industry’s role in the history and development of California. Though not affected by this HLB quarantine, the historic park and all citrus throughout Riverside are threatened by any presence of the disease.

    CDFA, in partnership with local agricultural commissioners, USDA and the citrus industry, continues to pursue its strategy of controlling the spread of the Asian citrus psyllids while researchers work to find a cure for the disease.

    HLB is known to be present in Mexico and in parts of the southern United States. Florida first detected the pest in 1998 and the disease in 2005. The University of Florida estimates that the disease causes an average loss of 7,513 jobs per year, and has cost growers $3 billion in lost revenue since it was first detected there. The Asian citrus psyllid was first detected in California in 2008.

    For more information about ACP or HLB, Riverside County residents may call the Agricultural Commissioner’s Office at (951) 955-3045 or CDFA’s toll-free pest hotline at 1-800-491-1899 or visit: www.cdfa.ca.gov/plant/acp/

  • Citrus Farmers Bracing To Battle Huanglongbing

    Exeter, Calif., (June 29, 2017) – 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.

    An abandoned orange grove in Florida. (Photo: USDA)

    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.”

    UCCE specialist Beth Grafton-Cardwell outlines research underway to detect huanglongbing disease of citrus.

    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.”

    The Citrus Research Board presented UCCE entomology specialist Joseph Morse, center, with a specially commissioned painting for his retirement June 30. Morse spoke at the Exeter meeting about citrus thrips, fuller rose beetle, and avocado thrips.

    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.”