California Fruit and Vegetable

Tag: Huanglongbing

  • “Grove-First” Approach to Combat Citrus Greening

    Since the mid-2000s, citrus greening disease or Huanglongbing (HLB), has taken a toll on citrus fruits, causing significant crop and economic losses for citrus growers from Florida to Texas, and threatening to make its way to California — the nation’s #1 citrus state.

     

    An aerial view of the new APHIS-funded Grove-First test site. Here researchers can partner with ARS scientists to evaluate therapies to combat citrus greening disease. (Photo by Cody Estes, owner of Estes Citrus Inc., Vero Beach, FL).

    Photo Caption: An aerial view of the new APHIS-funded Grove-First test site. Here researchers can partner with ARS scientists to evaluate therapies to combat citrus greening disease. (Photo by Cody Estes, owner of Estes Citrus Inc., Vero Beach, FL).

    With citrus trees in all major U.S. citrus-producing states affected by the bacterial pathogen, the Agricultural Research Service (ARS) is working to combat the disease. Citrus greening affects a variety of citrus fruits — with the greatest damage occurring within Florida’s orange groves.

    Through the project “Grove-First,” ARS scientists Michelle Heck and Randall Niedz are working to stop citrus greening from overtaking these vital crops. Grove-First invites fellow researchers, citrus growers, and industry experts to test their scientific models to curb the effects of citrus greening directly in the field.

    Coordinated by molecular biologist Heck at ARS’ Emerging Pests and Pathogens Research Laboratory in Ithaca, NY, and geneticist Niedz, who is based at the U.S. Horticultural Research Laboratory in Fort Pierce, FL, Grove-First will support any researcher who wants to test possible solutions directly in the field.

    “We want to provide access to anyone in the research community to test their therapy against citrus greening,” said Heck. “This new project is going to open the door [to further research] and obliterate the barrier between the lab and the field. We are going to provide researchers with the ability to test their therapies directly in the field.”

    With the support of ARS and USDA’s Animal and Plant Health Inspection Service (APHIS), Grove-First will leverage a commercial grove in Vero Beach, FL, to evaluate different treatments on both mature and young trees.

    “The only way to determine if a treatment works is to actually see it work in the field,” added Niedz. “When you have a woody perennial like citrus trees, they are large, and therefore expensive to grow. Most researchers simply don’t have the resources, or access to the trees. With Grove-First, we now have a field site to welcome collaborations with some of the best researchers in the country.”

    Heck tributes citrus growers for bringing Grove-First to fruition as a collaborative project. She said that in the past, the only way growers could fight citrus greening disease was to deliver therapies to trees using broadcast sprayers or through irrigation lines.

    Because citrus greening disease attacks the vascular tissue of citrus trees, many growers have now turned to injecting individual citrus trees with an antibiotic treatment, such as oxytetracycline, which delivers more immediate treatment.

    “The innovation to open up field testing and Grove-First research came from grower willingness to treat each individual citrus tree by direct injection,” said Heck. “This was transformative.”

    Grove-First will welcome researchers with three important considerations.

    “We want the treatments to be safe … safe for the (citrus) trees and safe for the workers,” Heck said. “They also must be affordable for the grower, and they must be available. The treatments that are safe, affordable, and available will be prioritized for screening through Grove-First.” – By Tami Terella-Faram, USDA-ARS Office of Communications

  • New Commercial HLB Detection Response Guide

    To ensure California citrus growers are well prepared in the event of a potential commercial grove detection of Huanglongbing (HLB), the deadly citrus plant disease that can be spread by the Asian citrus psyllid (ACP), the Citrus Pest and Disease Prevention Program (CPDPP) has developed a response guide for growers to utilize and educate themselves on the California Department of Food and Agriculture’s (CDFA) action plan.

    The Response Guide for a Confirmed HLB Positive Detection in a Commercial Grove details the steps taken by CDFA and actions required of the property or grove owner, as outlined in CDFA’s Action Plan.

    The actions in the response guide represent the most effective tools known to the citrus industry at this time and are meant to protect California’s citrus groves and support CDFA’s current required regulatory response. While, as of today, there have been no positive detections of HLB in a commercial citrus grove, the CPDPP recognizes the importance of proper preparation.

    In addition to the requirements outlined in the guide, growers are encouraged to use as many methods as feasible for their operation in order to limit the spread of the ACP and HLB.

    To read or download the response guide, please click HERE. If you have any questions or would like to order physical copies of this response guide, please visit our Resources page. — By the California Citrus Pest & Disease Prevention Program

  • Results from New Citrus Rootstock, Scion Combination Experimental Grove on HLB Tolerance

    As citrus growers in the west dreadfully anticipate the arrival of the citrus killing disease Huanglongbing, researchers in the already severely impacted state of Florida are making significant strides in learning how to combat this disease.

    Early results from a groundbreaking, large-scale citrus trial looking for solutions to the devastating citrus greening disease have given early hope for growers in the Indian River District. The new UF/IFAS research shows tree size does not seem to affect citrus susceptibility to greening.

    In the trial, researchers are testing which citrus rootstock and scion combinations will tolerate citrus greening, a deadly global citrus disease that nearly decimated the Florida citrus industry.

    Martin Zapien on one of the Millennium Block citrus cultivar trial planting days in 2019.

    Martin Zapien, a graduate student at the University of Florida Institute of Food and Agricultural Sciences Indian River Research and Education Center (UF/IFAS-IRREC), presented data from the Millennium Block citrus cultivar trial in Fort Pierce, Florida. At his thesis defense, the information Zapien represented was research from a 20-acre grove with grapefruit, navel orange and mandarin cultivars on a wide range of newly released and commercial rootstocks. Planted in 2019, the trees grow in a region where citrus greening is now endemic.

    Lorenzo Rossi, UF/IFAS plant root biologist and Tom James, a local citrus industry veteran, supervised Zapien’s research. Advisors on the project were UF/IFAS plant improvement team faculty Fred Gmitter, Jude Grosser and William Castle.

    Nearly 80% of Florida’s grapefruit crop is produced by Indian River District growers, who export their crop to Europe and Asia. That’s why scientists study the fruit so closely, said Rossi.

    “One of our objectives is to evaluate and compare the early performance of several new grapefruit hybrids grown on three commercial rootstocks under citrus greening conditions,” said Zapien.

    In the first two years of growth, the researchers compared UF rootstocks and scions by measuring tree growth and the trees’ ability to tolerate citrus greening. They expect to collect yield and fruit data after the third year, Zapien said.

    Rossi said data sets were specific to tree size, bacteria amount, the severity of citrus greening symptoms such as irregular yellow patches in the leaves, and leaf and soil nutrient concentrations.

    “We have seen many rootstocks that promote large and small tree size, but we have not seen any correlation between tree size and susceptibility to citrus greening,” Zapien said.

    But so far, the research does not support a theory that tree size affects citrus greening susceptibility, but there is a trend in small trees showing less citrus greening symptoms, Zapien said.

    Zapien said published research findings prove that high-density plantings produce higher fruit yields by increasing yield efficiency — fruit number per green foliage. The researchers will evaluate if the trees correlate with the published work or if the larger trees in the test grove produce more fruit.

    ‘Ray Ruby’ grapefruit on UFR-15 rootstock promotes vigorous trees — the trees show the largest canopies and are already flowering. But for UF/IFAS researchers to recommend a particular rootstock and scion combination, more data are required. The experimental grove must be examined for up to four more years before UF/IFAS scientists can make reliable recommendations.

    “All trees in the Millennium Block are infected with citrus greening. However, some trees are thriving,” Zapien said. “Trees on sour orange have shown significantly fewer disease symptoms than trees on x-639 and US-942 rootstocks, but we have to consider that sour orange’s drawback is the susceptibility to citrus tristeza virus.”

    As to citrus greening severity, ‘Star Ruby’ grapefruit showed only 4% symptoms in the green foliage. In contrast, ‘US Seedless Surprise’ symptoms were 24%. The other varieties fall between the two.

    “The data we compiled is nascent as the trees were only two years old at the analysis,” said Zapien. “University researchers will continue to monitor the top performer combinations to determine if the early findings are consistent.”

    With research in the UF/IFAS-IRREC experimental grove, Zapien completed a master’s degree in horticultural sciences. Zapien recommends that researchers improve sampling methods to assess the bacteria as the trees mature to advance the research. Zapien and his colleagues will evaluate flowering patterns to determine when the fruit is ready to harvest and reveals market windows. A long-term goal is to measure the yield or the amount of marketable fruit each tree produces. — By Robin Koestoyo, University of Florida, Institute of Food & Agricultural Sciences

  • Citrus Growers Encouraged to Increase Vigilance Following Recent ACP Detections in Central Valley

    Following recent Asian citrus psyllid (ACP) detections in the Central Valley over the last few weeks, growers, packers, haulers and all citrus industry members are encouraged to be extra vigilant in their ACP mitigation steps and adherence to regulatory practices.

    Recently, multiple ACP were detected on traps at a packinghouse in the Woodlake area of Tulare County. Upon confirmation, visual delimitation surveys began the following day. Live adults or nymphs were found and collected at two more adjacent properties, including an abandoned parcel with citrus host plants. CDFA is working closely with the packinghouse to ensure regulatory compliance. Treatment of host plants on residential properties within 400 meters of the detection will be conducted by CDFA once all necessary notifications, emergency proclamations and public meetings have been held. Commercial citrus operations within 800 meters of the detections will be asked to conduct treatments as well.

    Additionally, one ACP was recently detected on a trap at a juice plant in Visalia, and upon completion of the visual delimitation survey of the find site and adjacent properties, there were no additional finds.

    In Kern County, three ACP trap detections have been identified in the last week. One in the city, and two in rural residential locations in Southwest Bakersfield. These are the first ACP detections found in Kern County since November 2021. CDFA teams have already begun delimitation surveys and treatments will be conducted on residential properties with host plants within a 50-meter area around the detections once proper notifications, emergency proclamations and public meetings have been held. There are no commercial operations for several miles around the Kern County detections.

    These detections are a resounding reminder to continue to follow ACP mitigation best practices and regulatory requirements to efficiently suppress ACP populations and prevent the spread of Huanglongbing to the Central Valley.

     

    If you suspect ACP or Huanglongbing in your orchard, please notify the California Department of Food and Agriculture Pest Hotline at 1-800-491-1899. For questions, contact Kern County Grower Liaison Judy Zaninovich at jsleslie@msn.com, Northern Tulare County Grower Liaison Teri Blaser at tblasersci@ocsnet.net or Southern Tulare County Grower Liaison Jessica Leslie at jess.leslie@hotmail.com.

  • International Citrus Research Conferences Come to Riverside

    To explore and discover solutions to plant diseases impacting the global citrus industry, the 21st Conference of the International Organization of Citrus Virologists (IOCV) and the 6th International Research Conference on Huanglongbing (IRCHLB)are taking place at the Riverside Convention Center in Riverside from March 10-15, 2019.

    Co-organized by Citrus Research Board, the conferences will bring more than 500 attendees – from leading researchers and regulators to citrus growers – representing over 22 countries to Southern California, the birthplace of California’s iconic citrus trees. This is the first time the IOCV and IRCHLB conferences will be held in conjunction.

    The IOCV conference returns to Riverside for the first time since the inaugural Citrus Virus Diseases conference in 1957, which was organized on the occasion of the 50th anniversary of the founding of the Citrus Experiment Station at the University of California, Riverside in 1907*.

    The IOCV conference will take place from March 10-12, and features presentations on citrus leprosis, tristeza, yellow vein clearing and the de novo discovery of citrus viruses, as well as citrus viroids and diagnostics. In addition, for the first time in the history of IOCV, the conference will include sessions on non-graft-transmissible diseases of citrus.

    Taking place March 12-15, the IRCHLB will feature research presentations and interactive sessions on the global status of Huanglongbing (HLB), a summary of current HLB research efforts and the vision for long-term sustainable HLB management practices. HLB has killed hundreds of thousands of citrus trees in Florida and other countries, and is one of the biggest threats facing California’s commercial citrus industry.

    “California’s citrus community is honored to be hosting the Joint Conference of the IOCV and IRCHLB and hosting citrus researchers from around the world. We’re looking forward to learning about breakthroughs from our fellow scientists and collaborating with them to find sustainable solutions to the disease threats facing the citrus industry,”said UC Riverside Professor Georgios Vidalakis, chair of the Joint Conference. “On behalf of the conference, we are grateful for the support of Citrus Research Board – one of the leading citrus research organizations – and the staff that took the lead on organizing and hosting the conference.”

    About the Joint 2019 IOCV-IRCHLB Conferences 

    The 21st Conference of the International Organization of Citrus Virologists and the 6th International Research Conference on Huanglongbing is organized by the Citrus Research Board; the University of California, Riverside; and the United States Department of Agriculture’sAgricultural Research Service in collaboration with numerous citrus industry, state and federal government, and university partners. Learn more at www.iocvirchlb.com. 

    About Citrus Research Board

    Citrus Research Board administers the California Citrus Research Program, the grower-funded and grower-directed program established in 1968 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.

  • CA Detections of Citrus Disease HLB up 160 Percent

    HLB infected Tree

    Stakes at All-Time High for Backyard & Commercial Trees in 2019

    Detections of Huanglongbing (HLB), an incurable plant disease that kills citrus trees, increased by 160 percent in 2018 compared to the previous year, signaling the growing threat to the state’s iconic citrus trees, landscape and economy.

    HLB is spread by a small pest called the Asian citrus psyllid as it feeds on citrus tree leaves. The disease is not dangerous to humans or pets, but it is fatal for citrus trees and has no cure. Once a tree is confirmed with the disease, it must be removed from the property in order to protect neighboring citrus trees.

    The disease was first discovered in California in 2012 in Hacienda Heights. HLB was detected in 269 trees in 2017 and 699 trees in 2018, with a majority of these occurring in Los Angeles and Orange counties. The disease has not yet been detected in a California commercial grove.

    HLB has devastated commercial citrus production in Florida. Over the course of 10 years, Florida’s commercial citrus industry lost $7.8 billion in revenue, 162,200 citrus acres and more than 7,500 jobs due to HLB. Should the disease spread from backyard trees in Southern California to nearby commercial citrus groves, the livelihood of California’s citrus production could impact about 3,900 farmers and 292,000 acres of citrus production in the state. Commercially grown citrus contributes $7 billion in economic impact to the state and employs more than 22,000 individuals.

    “The livelihood of California’s commercial citrus industry and the generations of families it supports is at risk because of HLB,” said Jim Gorden, a citrus grower in the San Joaquin Valley and chair of the Citrus Pest & Disease Prevention Committee. “We are at a crossroads, and we must all work together to do what is necessary to protect our citrus.”

    Asian Citrus Psyllid Adults

    The California Department of Food and Agriculture (CDFA) has established quarantines throughout the state that limit the transport of citrus across state and international lines, and between areas where the psyllid and disease have been found. Additionally, CDFA has agriculture crews canvasing the state to inspect backyard citrus trees for the Asian citrus psyllid and HLB.

    “The Department is committed to our partnership with California’s commercial citrus industry and residential citrus growers to fight HLB,” said Victoria Hornbaker, interim director of the citrus program at CDFA. “With more than half of California residences estimated to have a citrus tree on their property, and California citrus production supporting billions of dollars in our state’s economy, we all play an instrumental role in protecting our citrus.”

    California residents play an important role in protecting the state’s citrus trees. Residents should: 

    • Proactively inspect their citrus trees for the Asian citrus psyllid and HLB monthly, and whenever watering, spraying, pruning or tending trees.
      • Adult Asian citrus psyllids are brown, about one-eighth of an inch long, and feed with their body at a 45-degree angle on citrus leaves.
      • Symptoms of HLB include blotchy and yellowing leaves, premature and excessive fruit drop, lopsided fruit, and bitter, inedible fruit.
    • Call the state’s pest hotline at 800-491-1899 if the pest or disease is spotted.
    • Cooperate with agriculture officials who may ask to inspect or treat their citrus tree.
    • As part of tree maintenance, visit a local nursery or garden center to get advice on products that can help protect citrus trees.
    • When pruning citrus trees, be sure to dry out citrus clippings or double bag them before removing the plant material from the property.
    • Refrain from moving citrus plants, foliage or fruit as doing this may unknowingly spread the pest.

    More information and photos of Asian citrus psyllids and HLB symptoms are available at CaliforniaCitrusThreat.org.

  • Huanglongbing Eradication Status in California Citrus

    To date, the deadly citrus greening disease Huanglongbing or HLB has not been found in California’s commercial citrus orchards; however, it’s only a matter of time. HLB strikes continue to be detected in residential areas, and its vector has spread all over the state. Watch this brief interview with Victoria Hornbaker, head of the CDFA’s statewide citrus program, as she shares the current status of the spread of HLB and its vector the Asian citrus psyllid, and CDFA’s eradication efforts. Read more about it in California Fresh Fruit Magazine.