California Ag Network

Tag: Huanglongbing

  • 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:

  • UC has Boots on the Ground in an Unrelenting Search for Asian Citrus Psyllid

    Ventura, Calif., (August 3, 2017) – With two magnifying loops around her neck and a truck stocked with vials and tools for insect collection, Joanne O’Sullivan scouts Ventura County citrus orchards every day. She walks the perimeter, examining newly emerging leaves and tapping branches with a PVC wand to bat pests onto her clipboard.

    O’Sullivan is one of four scouts hired and trained by UC Agriculture and Natural Resources scientists to carefully and continuously monitor citrus orchards for Asian citrus psyllid, an invasive pest in California that can spread the devastating huanglongbing disease.

    Joanne O’Sullivan is one of the scouts hired by UC to search for and collect Asian citrus psyllids.

    In Florida, where the pest was left unchecked when it first invaded citrus growing regions, the disease swept through the state. Citrus production in the Sunshine State plummeted 60 percent in 15 years.

    “We don’t want to let that happen here,” said Beth Grafton-Cardwell, UC Cooperative Extension entomology specialist. Grafton-Cardwell hired O’Sullivan and her colleagues who monitor citrus in San Diego, Imperial, Riverside and San Bernardino counties to scour dozens of orchards to document how treatments to control ACP are working. Next year scouts will be added in Tulare and Kern counties.

    When ACP are found, they are carefully bottled and sent to the lab to determine whether they carry the bacterium that causes huanglongbing disease.

    The expansive ACP monitoring effort is funded by a $1.45 million multi-agency coordination grant from the USDA. The project funds promising tools and long-term solutions to reduce the spread of huanglongbing. Led by Neil McRoberts, a professor of plant pathology at UC Davis, the grant also provides funds for two other activities.

    O’Sullivan taps branches with a PVC wand to knock off insects.

    One is a collaboration with California Citrus Mutual to offer free citrus tree removal to homeowners in areas where HLB is known to occur. The second is modeling data from the CDFA HLB survey program, in which psyllids and symptomatic plant tissue are tested for the bacteria. Trees may have the disease but not show symptoms, so testing the psyllids is a more effective way to find infected trees. The modeling work will improve the ability to predict the locations of infected trees.

    However, the main thrust is monitoring citrus treatments and their impacts on the ACP population with a team of scouts. A mix of conventional and organic farmers and growers who use biological integrated pest management programs to manage their orchards were recruited for the project. The farmers make ACP treatment decisions informed by research results that show the best treatments and timing.

    “Most growers are coordinating their treatments to get a bigger bang for their buck,” Grafton-Cardwell said.

    With just six months of data, the monitoring program has already yielded important information about Asian citrus psyllid.

    “We’re seeing more psyllids on the borders than the centers of groves,” Grafton-Cardwell said. “And so eventually, we will make recommendations that at certain times of year or when populations are low, the grower will only need to spray the borders of the grove.”

    If she finds ACP, O’Sullivan places them in vials to be sent to a lab for testing to determine whether they are carrying the bacterium that causes huanglongbing disease.

    This will reduce costs and the impact of pesticides on natural enemies.

    “The early data have also revealed which chemicals are the most effective for psyllid control. We’ve found that organic growers need to be more aggressive in the frequency of treatments, because the organic insecticides are not as effective as conventional insecticides,” she said.

    At 8 of the 49 Ventura County ranches in the project, yellow sticky traps were placed in trees to monitor for ACP’s natural enemies, including lady bugs, green lacewings, and Tamorixia radiata, tiny wasps from Pakistan that were released in California to battle ACP.

    When O’Sullivan sees one of the natural enemies at work in the field, she pauses to observe the process.

    “Sometimes I’ll see a lacewing munching on an ACP and I’ll say, ‘Go man, go!’” O’Sullivan said.

     

     

  • 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 Growers Reaffirm Support For State’s Citrus Pest & Disease Prevention Program

    Sacramento, Calif., (July 25, 2017) – California growers have affirmed the extension of a cooperative effort in response to the most serious threat to the state’s citrus crops.  Years before the discovery of the citrus pest the Asian citrus psyllid (ACP) in California in 2008 and the subsequent detection in 2012 of Huanglongbing (HLB), the disease spread by the ACP, California’s citrus growers had begun preparations for the arrival of this dual threat. Research and education efforts began well before the pest and disease were detected in Southern California, and since then a governing committee of citrus industry representatives has guided the state’s comprehensive response and advised the California Department of Food and Agriculture (CDFA).

    Huanglongbing is fatal for citrus trees and has no cure. The disease has been detected in more than 70 citrus trees in California, which have all been in urban areas of Los Angeles and Orange counties and have been removed. The Citrus Pest & Disease Prevention Program (CPDPP) — funded through industry assessments and state and federal funds — guides efforts to limit spread of the disease and the ACP, which can spread HLB from tree to tree as it feeds.

    The program was created in 2009 by legislation that included requirements for periodic hearings to review progress and give the industry and the public an opportunity to weigh in. Following a recent series of such hearings, the California Department of Food and Agriculture has determined it will continue the Citrus Pest & Disease Prevention Program.

    “It has never been more important to protect California’s citrus farmers, which represent a $3 billion economic driver for our state and 20,000 jobs,” said CDFA Secretary Karen Ross. “The feedback CDFA received from the industry was overwhelmingly supportive of this program.”

    Five hearings were held in June in citrus production areas to determine whether the program and its governing committee, both established in 2009, should continue for four more years. All comments received at the public hearings and in written submissions to the Department were supportive. No question of opposition was raised. Therefore, the Department determined a referendum is not warranted.

    “This program has evolved as the threat of the Asian citrus psyllid and Huanglongbing has progressed in the state, which is one of the reasons we’ve been successful at keeping the disease out of commercial groves,” said Nick Hill, chairman of the Citrus Pest & Disease Prevention Committee. “Having learned from our partners in Florida, outreach has occurred throughout the state and to urban areas, treatment coordinators have been engaged to make sure growers are working together for maximum effectiveness against the pest, and scientific research has been supported.”

    Continuation of the program reinforces the collaboration of the citrus industry, agriculture officials, researchers and the general public as they work together to save California citrus from HLB. Florida’s citrus industry has been decimated by the disease. An estimated 68.7 million boxes of citrus were harvested during Florida’s 2016-2017 harvest season compared to a record high of 244 million in 1997-1998

    Citrus Pest & Disease Prevention Committee meetings are open to the public. For a calendar of upcoming meetings, visit cdfa.ca.gov/citruscommittee/. For regional and statewide news related to citrus pests and diseases, sign up for emails at citrusinsider.org/.

  • 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.”

     

  • Citrus Disease Huanglongbing Detection And Quarantine In Orange County

    Sacramento, Calif., (May 25, 2017) – The California Department of Food and Agriculture (CDFA) and the United States Department of Agriculture (USDA) have confirmed the detections of the citrus disease known as huanglongbing (HLB), or citrus greening in Orange County. The disease was detected in plant material taken from a lemon tree in a residential neighborhood in La Habra and from three trees (2 lemon, 1 grapefruit) in a residential neighborhood in Anaheim.  HLB is a deadly disease of citrus plants and closely related species, and can be transmitted from tree to tree by the Asian citrus psyllid.

    CDFA,in cooperation with the USDA and the Orange County Agricultural Commissioner, has begun an extensive survey and limited treatment program in response to the detections.  CDFA crews have removed and disposed of the infected trees and are preparing to conduct treatment of citrus trees for Asian citrus psyllid infestations within 800 meters of the find sites.  By taking these steps, a critical reservoir of the disease and its vectors will be removed, which is essential to protect the surrounding citrus from this deadly disease.

    HLB is a bacterial disease that attacks the vascular system of plants.  It does not pose a threat to humans or animals.  The Asian citrus psyllid can spread the bacteria as the pest feeds on citrus trees and other plants. Once a tree is infected, there is no cure; it typically declines and dies within a few years.

    CDFA has expanded an existing HLB quarantine to include a portion of La Habra and will soon expand it further to Anaheim.  The quarantine prevents the sale of all host nursery stock and the movement of all host plants and fruits within a five-mile radius of the find sites, and applies to residents and commercial operations alike.  The HLB quarantine maps for Los Angeles and Orange Counties are available online at: www.cdfa.ca.gov/plant/pe/InteriorExclusion/hlb_quarantine.html. Please check this link for future quarantine expansions in these counties, should they occur.  Quarantines in new counties will be announced separately.

    CDFA, in partnership with the USDA, local county agricultural commissioners and the citrus industry, continues to pursue a 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, and the two have now been detected in all 30 citrus producing counties in that state.  The University of Florida estimates that the disease causes an average loss of 7,513 jobs per year, and has cost growers $2.994 billion in lost revenue since HLB was first detected there.

    The Asian citrus psyllid was first detected in California in 2008, and quarantines for the pest are now in place in 29 California counties.  If Californians have questions about the ACP or HLB, they may call CDFA’s toll-free pest hotline at 1-800-491-1899 or visit:   www.cdfa.ca.gov/plant/acp/

  • Fighting a citrus killer – from the University of California

     

    Credit: UC Riverside – UC Riverside researchers (from left) Philippe Rolshausen, David Jassby, Haizhou Liu, Caroline Roper, Georgios Vidalakis and James Borneman received a $5.1 million grant to fight a disease killing citrus trees.

    Riverside, Calif., (February 24, 2017) – A team of scientists, led by a group at the University of California, Riverside, has received a five-year, $5.1 million grant from the U.S. Department of Agriculture to fight a disease that is devastating the citrus industry.

    The team, led by Caroline Roper, an associate professor of plant pathology, will design and identify bactericides, which are chemicals that kill bacteria, to target Huanglongbing, a bacterial plant disease decimating citrus trees worldwide. They also will focus on better understanding the pathways those bactericides travel inside citrus trees.

    Huanglongbing, which has devastated citrus trees in Asia and South America, was detected in Florida in 2005 and has since led to a 75 percent decline in the Florida’s $9 billion citrus industry. Fifteen U.S. States or territories are under full or partial quarantine due to the presence of the Asian citrus psyllid, an insect which feeds on citrus trees and – in doing so –  transmits Huanglongbing.

    Past research has identified the bacterium (Candidatus Liberibacter asiaticus or CLas) associated with Huanglongbing that is killing citrus trees. But, it has proved difficult to deliver bactericides to the phloem, the part of the citrus tree where the harmful bacteria resides.

    The UC Riverside team will analyze phloem transit routes that bactericides take when introduced through common application methods, such as trunk injection or leaf or root applications.

    They also will continue to develop a new delivery system for use in field citrus trees. The delivery system targets the branches and petioles, which are the stalk that join a leaf to a stem. The idea is based on previous work that indicates that this is an effective and efficient way to tap into and introduce material into phloem tissue, a tissue that is hard to access.

    They also will conduct fluorescent tracer experiments that map phloem transport pathways in citrus and harness that information to predict and test the routes that bactericides take when introduced. This will yield information about the routes bactericides travel when administered through delivery methods used by growers and the branch/petiole feeding technique.

    The researchers will develop two classes of bactericides, the first based on mining anti-CLas compounds naturally produced by microbes that inhabit Huanglongbing survivor trees in Florida, and the second based on silver and sulfur nanoparticles.

    Finally, the researchers will also undertake an extension and outreach program for citrus growers and non-commercial citrus growers (homeowners and hobbyists). They also will perform an economic cost-benefit analysis for adoption of these treatments in the commercial citrus industry.

    In addition to Roper, the following UC Riverside scientists are involved: James Borneman, Philippe Rolshausen, David Jassby, Georgios Vidalakis, and Haizhou Liu. And, the following researchers from other institutions are involved: Robert Turgeon (Cornell University); Katherine Maloney (Point Loma Nazarene University); Pieter Dorrestein (UC San Diego); Greg McCollum (U.S. Department of Agriculture), and Jonathan Kaplan (California State University, Sacramento).

    The grant is one of four given by the U.S. Department of Agriculture’s National Institute of Food and Agriculture (NIFA) to combat Huanglongbing. The funding is made possible through NIFA’s Specialty Crop Research Initiative Citrus Disease Research and Extension Program, authorized by the 2014 Farm Bill.