California Fruit and Vegetable

Tag: HLB

  • University of Florida Awarded Grants to Continue Fight Against Citrus Greening

    University of Florida researchers hope to discover new methods to help citrus growers fight the deadly citrus greening (or Huanglongbing) disease with cost effective, long-term sustainable treatments with the support of recently awarded federal grants.  Three teams of scientists from UF’s Institute of Food and Agricultural Sciences received nearly $4.5 million in U.S. Department of Agriculture funds to study new ways to manage the invasive insect causing millions of damage to Florida’s citrus crops.

    “These grants build on an existing portfolio of success in finding solutions to combat citrus greening throughout Florida’s citrus groves,” said Michael Rogers, director of UF/IFAS Citrus Research and Education Center and coordinator of the UF/IFAS statewide citrus program. “They will contribute to the solutions we are providing that support citrus growers in sustainably and profitably growing citrus throughout the state.”

    Managing the Asian citrus psyllid with the environment in mind

    Bryony Bonning, eminent scholar and professor in entomology and nematology, leads a team from Gainesville and the UF/IFAS Citrus Research and Education Center in Lake Alfred, Florida in a project that uses a bacteria-derived pesticidal protein combined with gene silencing to manage the invasive Asian citrus psyllid (ACP) population. The long-term goal of the proposed work is to create an environmentally benign approach for citrus growers to control ACP that works within an integrated pest management (IPM) strategy. The project intends to identify the optimal components for an ACP control product for grower use.

    The grant project aims to: 1) optimize ACP-active proteins derived from the bacterium Bacillus thuringiensis (Bt) that suppress psyllid populations, 2) further develop genetic solutions that would disrupt ACP, and 3) screen for the best combination of these methods for use against ACP. On completion of this project, researchers will be well positioned to produce transgenic citrus and/or trap plants that will suppress ACP populations for use by citrus growers.

    This method of effective vector control, combined with other measures will help the citrus industry in Florida rebound, and protect the industries in California and Texas. The results of this research are anticipated to reduce the need for tree removal and replanting as well as reduce insecticide applications, and increase yields and fruit quality, contributing to the long-term profitability and sustainability of U.S. citrus production.

    Attacking citrus greening from the inside out

    Amit Levy, assistant professor of plant pathology, received a NIFA grant to examine how the Candidatus Liberibacter asiaticus (CLas) bacteria interacts with a narrow tissue – known as the phloem – which is buried inside the stem of the citrus tree. CLas resides in and plugs the phloem in the stem of the citrus tree, leading to inhibition of sugar and nutrient transport into the tree’s sink tissues, including the fruit. Eliminating these plugs can presumably result in renewed sugar transport and increased fruit yields.

    However, there is a significant gap in understanding CLas-phloem interactions in citrus, which has been a major limiting factor for controlling the disease. Levy and a team of UF/IFAS researchers and Sainsbury lab and Cornell University scientists plan to address these challenges with a novel seed coat-based system that supports in-depth analyses of phloem dynamics and CLas-phloem interactions in HLB-affected citrus. The project will identify key players required for phloem plugging, host immune response and CLas colonization inside the phloem. These key players can later become novel targets for manipulation with gene editing techniques that can be translated into usable products, such as transgene-free CRISPR/Cas9 edited plants to block the disease propagation and movement, and increase sugar and nutrient translocation into fruit thus increasing tolerance or resistance to HLB.

    A Novel Therapeutic Strategy For HLB-Infected Trees

    Huanglongbing (HLB)-resistant or tolerant citrus trees are the long-term solution for citrus greening disease.  Existing research has generated transgenic citrus lines that provide robust tolerance to HLB. These transgenic lines are already in field tests as a potential management possibility for HLB. However, these trees will have to go through an extensive approval process before being made available to growers.

    A research team lead by UF/IFAS microbiology and cell science professor Zhonglin Mou and faculty from the UF/IFAS Citrus Research and Education Center and UF/IFAS Southwest Research and Education Center are working to speed up this process by reproducing the greening resistant or tolerant genetic makeup in non-transgenetically modified plants by gene editing using CRISPR/Cas9. This is a better long-term approach but will take time.

    The primary goal of this project is to develop an interim treatment for HLB. The project hopes to turn off the genes that negatively control the citrus immune system and result in disease symptoms in citrus when exposed to disease-causing pathogens. Coupled with other work to target the HLB-causing bacterium itself, the overall goal is to develop new management strategies making citrus varieties highly tolerant to this disease. The project will use a vector derived from citrus tristeza virus (CTV) to remove negative regulation of the citrus immune system, leading to improved immune response and HLB tolerance. The same CTV vector will also deliver antimicrobial peptides to reduce HLB pathogens.

    The synergism between the immune system-provided tolerance and the antimicrobial peptide-mediated pathogen reduction is expected to provide effective control of the HLB disease. Importantly, CTV naturally occurs in the field and does not make genetic changes to the citrus genome, and thus the employed strategy is a non-transgenic approach. — By Ruth Borger, University of Florida

    The mission of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) is to develop knowledge relevant to agricultural, human and natural resources and to make that knowledge available to sustain and enhance the quality of human life. With more than a dozen research facilities, 67 county Extension offices, and award-winning students and faculty in the UF College of Agricultural and Life Sciences, UF/IFAS brings science-based solutions to the state’s agricultural and natural resources industries, and all Florida residents.

  • $45 Million in Funding for Citrus Research Awarded

    A total of $45 million in funding for citrus research during the 2020-21 fiscal year was awarded by the United States Department of Agriculture National Institute of Food and Agriculture (USDA-NIFA) Emergency Citrus Disease Research and Extension (ECDRE) Program. The ECDRE Program addresses priorities identified by the Citrus Disease Sub-Committee of the National Agricultural Research, Education, Extension, and Economics (NAREEE) Advisory Board by sponsoring research projects designed to provide solutions to the U.S. citrus industry. For the 2020 fiscal year, the ECDRE program selected 12 projects to receive awards.

    With funding support from the Citrus Research Board (CRB), Pepsi Co and Coca-Cola, and a consortium led by the Citrus Research and Development Foundation (CRDF), NIFA awarded a $10 million grant for their on-going coordinated agricultural project with Bayer Crop Science. The project seeks to identify and develop therapeutics for HLB and the presumed HLB pathogen ‘Candidatus Liberibacter asiaticus’ (CLas). Researchers are investigating synthetic and microbial therapeutics for further characterization and optimization, intending to develop therapeutics for commercialization.

    According to the CRB President, Marcy Martin, “Success with this project will help all citrus growers, not just those from a particular state. We like that CRDF and CRB were able to team up on this worthy project.”

    Among this year’s awardees, three current and past CRB-funded California researchers from the University of California were awarded $12.5 million between three projects. CRB-funded researcher Chandrika Ramadugu, Ph.D., was awarded $4.7 million to lead efforts to evaluate novel citrus hybrids for tolerance/resistance to HLB in multi-state field trials in California, Texas, and Florida. Caroline Roper, Ph.D., received $6.5 million to unravel the underlying mechanisms of tree health in HLB impacted groves and develop a set of best practices for extending the life and productivity of citrus groves. Past-funded CRB researcher Yen-Wen Kuo, Ph.D., was awarded $1.41 million to explore utilizing insect-specific viruses to manipulate the Asian citrus psyllid (ACP) and its associated microbes to limit psyllid activity and disease spread potentially.

    CRB-funded researchers Vivian Irish, Ph.D., from Yale University, Anne Simon, Ph.D., from the University of Maryland, and Robert Shatters, Ph.D., from the USDA Agricultural Research Service also received awards. Irish is spearheading research with a $1.5 million award to identify HLB susceptibility genes in citrus, which will assist in future breeding efforts. Simon received $1.5 million to lead efforts to develop a phloem-restricted viral vector that could be used to directly target CLas in the phloem or modulate citrus host responses. Shatters has received $9.4 million to explore the development of an in-field therapeutic screening system with accompanying delivery systems. Past-funded CRB researcher Goutam Gupta, Ph.D., was awarded $4.8 million to lead efforts in developing novel therapies for the prophylactic and curative treatment of HLB.

    Additionally, researchers from the University of Florida and the University of Maryland received awards to study CLas, ACP and HLB strategies.

    Click here for more information on project scope and activities can be found at. The CRB congratulates all awardees for the 2020 fiscal year cycle and looks forward to seeing the results from these studies.
     
    About the Citrus Research Board

    The CRB administers the California Citrus Research Program, the grower-funded and grower-directed program established in 1968 under the California Marketing Act as the mechanism enabling the state’s citrus producers to sponsor and support needed research. More information about the Citrus Research Board may be found at www.citrusresearch.org.

  • CDFA Accepting Proposals for Riverside County Grower Liaison

    The California Department of Food and Agriculture (CDFA) is currently accepting proposals for its Request for Proposal for a contractor to serve as the Riverside County grower liaison. Proposals must be received by Nov. 18. Responsibilities may include conducting outreach directly to growers in Riverside County, providing them up-to-date information on the latest industry news or updates, staying engaged in CDFA activities, communicating voluntary or mandatory treatments Riverside County and more.

    The battle to save California citrus from the Asian citrus psyllid (ACP) and Huanglongbing (HLB) is a collaborative effort that involves local, county, state and federal officials, researchers, scientists and commercial citrus growers. To help facilitate pest management and disease eradication, grower liaisons are key pieces to that puzzle and are dedicated to serving a specific region in the fight against HLB.

    This position requires a fundamental knowledge of citrus production, a working knowledge of grove operations, and the relationship between growers, shippers and allied businesses that work in the area of pest and disease control. A Pest Control Advisor’s license is desirable, but not required. The contractor should be familiar with California agriculture and specifically its citrus industry. Knowledge of the ACP and HLB is desirable.

    To submit a bid for the contract, you must follow these steps:

    • Visit ca.gov, if you do not have a profile you must register for one in order to view the Request for Proposal (RFP).
    • Once logged in, visit the Get Public Procurement Information page and select “See current bids.”
    • Under “Search Events,” type in “Asian Citrus Psyllid Outreach and Education.”
    • Once on the Events Details page, click “View Event Package,” then under the “View Attachments” area, click “view” to download the official Request for Proposal. Once there, you should be able to view the full RFP and Start a Bid if you meet the qualifications. Please note, you must have a profile and be logged in to view the RFP.

    Proposals are due to CDFA by Nov. 18 at 2 p.m. The term of this contract is Dec. 1, 2020 or upon final signature, whichever is later, through Nov. 30, 2022.

    For additional questions, contact Contracts Analyst Donna Weber at donna.weber@cdfa.ca.gov.

  • To all San Joaquin Valley Citrus Growers

    The ACP/HLB San Joaquin Valley Task Force called a meeting on October 8, 2020 due to the increased number of ACP trap finds in the southern part of Kern County. In the last month (September and into October), there

    have been a total of 35 ACP trap finds in the areas of the south part of Bakersfield, Arvin, Lamont, Mettler, and Maricopa. There were 15 residential and 20 commercial citrus sticky trap finds. While there have been finds in

    some of these areas in the past, the amount of detections in this last 30-day period is alarming. The Asian citrus psyllid, as a reminder, transmits Huanglongbing; the best way to avoid HLB is to control ACP which the valley has been successfully doing. 2020 has been a suspiciously quiet year for ACP finds but now, it is time to act.

    We are now in the late part of the season where most spray programs have already been executed. A coordinated spray is not recommended at this time. Kern County growers are encouraged to use an ACP effective material if they have not done so in the last six weeks. It is prudent for all growers to use ACP effective materials when treating other pests. Regarding the residential finds, CDFA is at various stages of treating them. Prior to these finds, CDFA had released Tamarixia radiata in certain residential areas of Kern County. Future Tamarixia releases are scheduled.

    The task force wants to convey the seriousness of what is being seen and what it means to our industry. Unfortunately, the suspicion is that these finds in commercial citrus are spilling over from residential properties. It is up to the citrus industry to deal with this threat. San Joaquin Valley citrus growers have done a good job using ACP effective materials when treating. The cooperation shown by growers during coordinated treatments reflects their commitment to keeping ACP suppressed. Nevertheless, task force members wished to highlight what should be done to help control the Asian citrus psyllid here in the valley.

    It is even more imperative to control the psyllid due to the find of a CLas positive ACP in commercial citrus down in the Riverside area. That was a wake-up call. We cannot, as an industry and in good conscience, dismiss that find. Growers and Pest Control Advisors need to be diligent. The following best practices must be a part of the regime tending to citrus groves.

    What do Growers and Pest Control Advisors need to do? It is easy to say, “follow the best practices”, but there are key elements that the task force believes is important. All the guidelines should be adhered to, but these are the key elements:

    A. Know When and Where Asian citrus psyllids might be present.
    – flush is what attracts the psyllid. Nice, tender leaves and stems. Like candy to an ACP.
    – citrus varieties matter. Lemons flush constantly. Grapefruit, oranges, and mandarins will have fewer flush cycles.
    – know when flushes occur. Spring, late summer for established trees. Younger trees have extensive, prolonged flush. Topping and hedging will produce flush. Spraying with kaolin stimulates flush also.

    – temperature determines how long a flush will last. Hot temps lead to quick hardening of the plant growth. Cooler temps prolong flush.

    1. Scout for Asian citrus psyllids (Yellow sticky traps are a passive method to determine presence of ACP).

      – use both visual and tap surveying.
      – survey along the borders, psyllids tend to not go deeper into groves unless the population is high (they do not like each other very much). If very wide plantings or very wide wind machine rows exist, then check along them too. Younger trees and shorter trees will allow the psyllids to travel farther into the grove.
      – do more frequent surveys during flush. Monthly surveys work when the vegetation is hardened off, unless the trees are close to a find, then sampling frequency should increase.

    2. Be aware of inadvertently transporting ACP.
      – clean equipment used before moving to the next property. Applies to anyone working in a grove; especially picking crews, trimming crews, irrigators, Pest Control Advisors, and the growers themselves.
      – check clothing and vehicles for insect hitchhikers. Shake out hats, bags, clothing. Sweep down vehicles.
      – do not park vehicles in the rows, park outside of the grove.

    3. If possible, use ACP effective materials when treating other pests, following label instructions.

    4. Follow the requirements when moving bulk harvested citrus.

    5. Be aware of developments!
      – receive newsletters from San Joaquin Valley Grower Liaisons.

    Fresno County Northern Tulare County Southern Tulare County Kern County

    – subscribe to industry publications.

    Sylvie Robillard Teri Blaser Jessica Leslie Judy Zaninovich

    FresnoACP@yahoo.com TBlaserSCI@ocsnet.net jess.leslie@hotmail.com jleslie@msn.com

    These were felt to be the most important points of the voluntary best practices. The ACP/HLB San Joaquin Valley Tack Force felt it was important to write this letter to all the valley citrus growers because as of this moment, the valley has not discovered a CLas positive Asian citrus psyllid or a CLas positive tree. The members of the task force believe that the industry must operate under the assumption that there are positive psyllids and trees in the valley; they just have not been found yet. If the industry relaxes its vigilance that is when Huanglongbing will become established and cause havoc. Thank you for taking the time to read this and may each and all stay safe and well.

    Sincerely,

    The ACP/HLB San Joaquin Valley Task Force 

  • HLB Detection Triggers Quarantine Expansion in San Bernardino & Los Angeles Counties

    A quarantine expansion has been declared following the detection of the citrus disease Huanglongbing (HLB), or citrus greening, in five residential citrus trees located in Rancho Cucamonga. This is the first time the disease has been confirmed in Ranch Cucamonga, marking the fifth city in San Bernardino County to have had a positive detection of HLB. The California Department of Food and Agriculture (CDFA) is working with the United States Department of Agriculture (USDA) and San Bernardino County to remove the HLB-infected tree and prevent the spread of HLB into neighboring areas.

    The expanded quarantine area will merge with the existing quarantines in San Bernardino and Los Angeles Counties. The expanded portion is bordered on the north by Big Tree Cucamonga; on the west by Pauda Avenue in Claremont and Mount Baldy Road; on the east by Interstate 15; and on the south by Foothill Boulevard and Interstate 10 in San Bernardino County.

    The updated HLB quarantine maps for San Bernardino and Los Angeles counties are available online. Please check this link for future quarantine expansions in these counties, should they occur.

    The quarantine prohibits the movement of all plant parts or citrus nursery stock out of the quarantine area. Provisions exist to allow the movement of commercially cleaned and packed citrus fruit. If you are a grower within the new quarantine expansion area, please contact CDFA’s emergency quarantine response program at 916-654-0312 for information on these provisions.

    Fruit that is not commercially cleaned and packed, including residential citrus, such as oranges, lemons, grapefruits and kumquats, must not be moved from the property on which it is grown, although it may be processed (removal of stems and leaves, and a thorough washing) and/or consumed on the premises.

    Residents are urged to take several steps to help protect citrus trees:

    • Do not move citrus plants, leaves, or foliage into or out of the quarantine area or across state or international borders. Keep it local.
    • Cooperate with agricultural officials placing traps, inspecting trees, and treating for the pest.
    • If you no longer wish to care for your citrus tree, consider removing it so it does not become a host to the pest and disease.

    CDFA staff have scheduled removal of the infected tree and are in the midst of a treatment program for citrus trees within 250-meters of the find site. By taking this action, a critical reservoir of the disease and its vectors will be removed, which is essential to protect other citrus trees on the property, neighbors’ trees and the community’s citrus from this deadly disease. CDFA, in partnership with USDA, local county agricultural commissioners and the citrus industry, continue to pursue a strategy of controlling the spread of the Asian citrus psyllids while researchers work to find a cure for HLB.

    Questions? If you are a citrus grower in San Bernardino County and have questions about this detection, please contact your grower liaison Sandra Zwaal at szwaal2@gmail.com.

  • New Targets for Huanglongbing Treatments

    Scientists are closer to gaining the upper hand on a disease that has wiped out citrus orchards across the globe. New models of the bacterium linked to the disease reveal control methods that were previously unavailable.

    Metabolic models of organisms are like road maps of cities. “They show you all the biological processes, and how they work together,” said UC Riverside microbiology professor James Borneman. “They also show you which molecular pathways, if blocked, will kill the organism.” 

    Simplified metabolic model and its striking similarity to a road map. (Metallo&Vander Heiden)

    In this case, researchers created the first models of the bacterium associated with Huanglongbing or HLB, also known as citrus greening disease. The team’s work is described in a new paper published in Nature’s npj Systems Biology and Applications.

    The research team made models for six different strains of the bacterium known as CLas and doing so enabled them to identify as many as 94 enzymes essential for the bacterium’s survival. These enzymes can now be considered targets for the creation of new antibacterial treatments.

    In addition, the team identified metabolites required for the bacteria to grow.

    “Just like when humans break down the food they eat into small components called metabolites, which feed our cells, bacterial cells also require metabolites for their growth,” Borneman said.

    Knowing the metabolites needed for CLas’ growth could enable scientists to cultivate it in a laboratory setting. It is not currently possible to grow CLas on its own, hindering scientists’ ability to study it and ultimately to manage it.

    This research project involved a collaboration between UC Riverside, UC San Diego, Texas A&M University, and the U.S. Department of Agriculture. In addition to Borneman, members of the modeling team included UCR plant pathologist Georgios Vidalakis and UCSD systems biologist Karsten Zengler.

    UC Riverside is at the forefront of efforts to combat Huanglongbing. Other important areas of research include antibacterial development and delivery, immune system fortification in citrus, engineering resistant citrus via a detailed understanding of host-microbe interactions, breeding resistant citrus, and insect management, among others.

    Because microbes tend to mutate and acquire resistance mechanisms in response to drugs and other efforts to thwart them, Borneman cautions that any one solution to the problem may be short-lived.

    Transmission electron microscope image of CLas bacterium. (J.M. Bové/INRA)

    “Microbes almost always adapt to control measures, perpetuating the ‘arms race’ between pathogens and hosts,” Borneman said. “There won’t be one thing that will fix this disease. We likely will need to address all three components associated with the disease — the bacterium, the insect that transmits it, and the citrus plants — to find a long-lasting solution.”

    To that end, the research team is constructing metabolic models of citrus and the insect, the Asian citrus psyllid.

    “We expect that this multiorganism modeling endeavor will provide new insights into the mechanisms underlying this disease, which will lead to effective and sustainable Huanglongbing management strategies,” Borneman said. — By Jules Bernstein, UC Riverside

  • Barking Up the Right Tree: Canines Detect HLB

    In September 2019, huanglongbing—also known as HLB or citrus greening—was detected in residential citrus trees located in Ventura County, in southern California (and just recently, the first HLB carrying Asian Citrus Psyllid was detected in a commercial CA citrus grove).

    During an orchard review in California, expert detector dog, Szaboles alerts his trainer by sitting next to a citrus tree infected with Huanglongbing (HLB).

    The disease, which has no known cure, is caused by a bacterium that devastates citrus plants and is transmitted by psyllids (small plant-eating insects resembling lice) that carry the bacteria from tree to tree or by the grafting of infected plant material. Common symptoms of infection include blotchy mottling of entire leaves, premature defoliation of the tree, and fruits that are usually small, with green peel at the bottom and a bitter taste. Unfortunately, these visible signs of HLB do not manifest until months or even years after the initial infection. By then, it is too late for citrus growers to save their crop from a mass infestation.

    However, the Farm Bureau of Ventura County found a rather unconventional way around this problem.

    To contain the infected trees and prevent a citrus epidemic, the Farm Bureau decided to hire a team of detector dogs specially trained to find HLB bacteria. The dogs are a result of a unique program funded by USDA and run by Agricultural Research Service (ARS) Research Leader and Plant Pathologist Timothy Gottwald (now retired) at the U.S. Horticultural Research Laboratoryin Fort Pierce, FL.

    First, the clever canines patrolled the perimeter because the edges of a grove are where the disease would first accumulate. Then, they trotted through the grove of trees to ultimately identify over 200 infected trees from a grove of 3,500.

    According to Gottwald’s research, the canine-detection method has an accuracy rate of 99 percent. While humans need several minutes to visually examine each tree and collect samples for laboratory testing (which requires considerable lab time and supplies), the dogs can travel through groves of trees in mere minutes, sensing HLB-infected trees by smell faster and far more easily. The time saved in finding the disease earlier gives citrus growers the opportunity to remove and destroy or quarantine HLB-infected trees, controlling what could’ve been a severe outbreak and loss of crop.
     

    However, there are still some considerations to keep in mind when deploying the canines as an early detection technology. Each dog team can only work 30 minutes at a time before they must rest, and a new team takes over. Teams can work for about 6 hours a day. In addition, much like any lab equipment, dogs are periodically calibrated to the HLB “scent signature” to remain finely honed optimized detectors.

    Still, the dogs are more sensitive and accurate than any other available technology in the field. The employment of detector dogs is still a voluntary program, which means fruit growers and farmers have the choice to either use dogs to find HLB early or continue using a USDA-approved DNA test called polymerase chain reaction (PCR).

    “While PCR is an effective way to detect infections, it isn’t efficient,” Gottwald explained. “It’s difficult to pinpoint incomplete infections—or infections that are only on one part of a plant (for example, a single leaf out of an entire tree with possibly thousands of leaves)—using PCR because it requires numerous samples from all over the suspect specimen.”

    “On the other hand,” Gottwald continued, “detector dogs identify pathogens ‘holistically,’ easily locating minute infections regardless of what small part of the tree they are infecting.” With this increased scope and accuracy rate, Gottwald and his colleagues believe that the canines’ abilities will revolutionize how growers protect their crops.

    “These specially trained canines may also be used to detect diseases and infections in other fruits and vegetables, such as grapes, peaches, plums, and tomatoes,” he said. “Our research has shown that they can sense pathogens like plum pox virus or squash vein yellowing virus, which both can cause severe economic losses to agriculture industries.”

    The canine-detection method was validated in blind tests by USDA ARS in collaboration with the California Department of Food and Agriculture, with results published in 2020.— By Georgia Jiang, USDA-ARS

  • CLas-positive Asian Citrus Psyllid Found in Riverside Commercial Grove

    An Asian citrus psyllid (ACP) sample – confirmed positive for Candidatus Liberibacter asiaticus (CLas) the bacteria that causes Huanglongbing (HLB) – was collected from a commercial citrus grove in the Woodcrest area of Riverside County. Confirmed by Citrus Research Board’s Jerry Dimitman Laboratory, this single adult psyllid is the first CLas-positive ACP found in a commercial citrus grove in California.

    While a positive ACP detection in a commercial grove is cause for serious concern, as of today, HLB has not been detected in any California commercial groves. That said, it is more crucial than ever that we stop the disease from spreading by eradicating the Asian citrus psyllid in commercial groves. The cost to manage the Asian citrus psyllid is far less than any potential costs or loss to the industry should HLB take hold throughout our state.

    An expansion of the HLB quarantine zone will not be established as a result of the CLas-positive ACP detection and CDFA staff is swiftly conducting surveys and collecting samples per the ACP/HLB Action Plan  from the perimeter of all commercial groves and all residential HLB host plants that are located within a 250-meter radius around the find.

    While treatment is not mandatory as a result of the detection, all growers within 250-meters of the find site will be notified to apply insecticides to all HLB host material within the designated area with materials recommended by the University of California (UC).

    Currently, the best way to stop the disease from spreading is to stop the ACP. To stop the ACP, we must restrict its movement and suppress existing psyllid populations. It is critical to follow best practices and review recommendations from the UC on how to protect commercial citrus groves from HLB. Regulations are in place to help prevent the spread of the pest and disease. All growers, packers and haulers must comply with all California Department of Food and Agriculture, county and federal regulations, including quarantines.

    Growers in Riverside County may contact the County Agricultural Commissioner’s office or the CDFA Pest Hotline at 800-491-1899 for additional information. If you see or suspect ACP or HLB symptoms in your grove, please notify the CDFA hotline. – By the Citrus Pest & Disease Prevention Program

  • Best Practices Video for Field Crew During Citrus Harvest for Pest/Disease Prevention

    To provide industry members, including field crews, with best practices to prevent the spread of the Asian citrus psyllid (ACP) in California’s citrus groves, the Citrus Pest & Disease Prevention Program has developed a mobile-friendly, Spanish-language field crew training video that can be used by field crew supervisors and farm labor contractors prior to harvest.
     
    This video, which stems directly from our in-person train-the-trainer workshops, provides an overview of best practices for field crews to prevent Huanglongbing (HLB) from threatening the California citrus industry’s livelihood and infecting commercial groves.
     

    A direct, downloadable version of this video is available here.

    We all must do our part if we’re going to protect California citrus from this disease – and field crews are at the forefront. For additional resources and videos, please visit CitrusInsider.org/Resources.

  • Automated Delivery System for Therapeutic Materials to Treat HLB Infected Citrus

    Why is this research needed?

    In 2005, a disease called Huanglongbing (HLB, citrus greening, was identified in Florida’s commercial citrus groves. The disease is caused by a bacterium that affects all citrus cultivars by disrupting the flow of nutrients from the source of production, to the site of use, causing tree decline. HLB weakens the root system, increases early fruit and leaf drop, lowers tree productivity and fruit quality and ultimately kills the tree. The disease has spread to all the major production regions in Florida. Economic losses have exceeded more than $4 billion dollars. Currently, more than 95% of Florida’s trees are infected. There is currently no cure for the disease.

    Efforts to control HLB have been unsuccessful as the bacterium cannot be cultured, literally grown, in a petri dish, and once in the plant it proliferates within the citrus phloem. Phloem is the system that transports sugars from their site of production, the leaves, to plant parts that use sugars, the roots or flowers.Phloem transport is generally downward but can be upward as well.

    Once the HLB bacterium is in a tree’s phloem it has the potential to infect the entire tree. It is exceedingly difficult to introduce any control agent into the phloem with the conventional control methods of foliar spraying or soil drenching.

    Thus far, no treatment preventing HLB infection, or controlling the bacterium once within the tree, has been developed. Potential chemicals are being investigated, but in order to test them, direct or indirect phloem delivery, where the bacterium proliferates, is needed. Therefore, an effective method of delivering an effective volume of theraputics into the phloem is needed to evaluate potential treatments.

    What is the focus of this project?

    Our project focuses on developing a method of delivering therapeutic liquid materials, bactericides, microbial metabolites, RNAi, or biologicals, into the citrus vascular tissues, both the xylem which conducts water and nutrients upward from the roots and the phloem, which conducts sugars and other metabolic products downward from the leaves. We are investigating diffusion, trunk punctures with a surrounding liquid reservoir for passive uptake and infusion, low pressure active injections. We are focusing on these methods as foliar sprays and root drenches have not been successful phloem delivery methods.

    Who will be doing the research?

    The project is led by plant pathologist Dr. Ozgur Batuman with colleagues at the Southwest Florida Research and Education Center (SWFREC) at University of Florida in Immokalee. This four-year project will also study the citrus vascular system with a multidisciplinary research team including UF Plant Pathologists Drs. Nabil Killiny and Amit Levy at Lake Alfred, SWFREC UF Plant Physiologist Ute Albrecht, Citrus Horticulturist Fernando Alferez, Precision Ag. Engineer Yiannis Ampatzidis, Agricultural and Natural Resources Economist Tara Wade, University of California-Davis Extension Specialist Louise Ferguson and Texas A&M-Kingsville Citrus Center Plant Pathologist Veronica Ancona as well as number of graduate students, postdocs, and Florida, Texas and California citrus industry members.

    How will this research be done?

    Our earlier research involving comparisons of delivery methods including foliar sprays, soil drenching and trunk injection determined Needle-Assisted Trunk Infusion (NATI) was the best potential delivery method (Figure.1). In initial experiments, using NATI, 1 ml of rhodamine (1%) dye was injected into the trunks of one-year-old citrus seedlings. A visible red color, indicative of rhodamine uptake and movement, was detected in the upper-most leaves within 30-60 min and an increase in color intensity was observed within 24 hours. Similar results were observed in two-year-old grafted Valencia plants within 48 hours. If the NATI delivery method can be automated, large numbers of trees could be treated quickly. Once the delivery method has been developed, implementation will be tested with potential treatments developed within other research projects.

    Our proposed automated delivery would consist of a robotic arm with several modules at the end of the arm, installed on an ATV or tractor. One module with needles would grip and puncture the trunk, a second module would wrap a reservoir around the trunk below the punctures and third module would fill the reservoir. (Figure 2). Hopefully, a robotic arm plus automated system will be inexpensive enough for growers to purchase and simple enough to use.

    Another approach is disease prevention; application pf prophylactic chemicals that prevent infection. In this scenario our system would be used treat healthy young trees with bactericides or boost their immune system. When infected by the ACP the bacterium would either be killed or suppressed, perhaps below the level that harms tree growth and productivity. This option is analogous to the vaccinations that prevent diseases in humans and animals.

    What are the greatest challenges and opportunities?

    The greatest challenge is successful phloem delivery. The greatest opportunity is that, if successful, we will have developed a method that will allow much more precise deliver of theraputics to citrus trees. For example, if an effective phloem delivery method is developed, it could be used to control insects that feed on citrus plant parts. Or, it could be used to deliver growth regulators, perhaps nutrients and carbohydrates, to roots and fruits to increase growth, development and fruit quality; much like an intravenous injection functions in an animal.

    Among the questions we hope to investigate are:

    • When, what kind of, and what amount of therapeutics can be applied by NATI?
    • At what frequency?
    • What type of citrus tree: cultivar, age, infected, healthy is the best for treatment by NATI?
    • Can we kill the bacterium? How and when to assess a change in bacteria titer after treatment?
    • When will become available and be economically feasible for growers?
     — By Ozgur Batuman, Southwest Florida Research and Education Center, University of Florida; and Louise Ferguson, Department of Plant Sciences, University of California Davis
    Figure 1. Distribution of rhodamine (red dye; 1%) applied by NATI in various tissues (left) of grafted and non-grafted young citrus plants grown in the greenhouse (right). Photos taken 2 weeks after the treatments. Treatments and tissues observed are indicated. Yo = year-old.
    Figure 2. Projected automated delivery system (ADS); an ATV with extendable arm with NATI and the cover placement systems on the arm guided onto the tree trunk.