California Fruit and Vegetable

Tag: citrus greening disease

  • UC Seeks Consumers to Weigh in on New Method of Controlling Asian Citrus Psyllids

    To understand consumers’ attitudes toward a bioengineered pesticide for citrus crops, University of California Agriculture and Natural Resources researchers are asking for volunteers to participate in focus groups in Riverside, Oakland and Fresno.

    Bacillus thuringiensis, or Bt, is a naturally occurring bacterium being tested to control the spread of Asian citrus psyllid, the small insect that transmits the disease huanglongbing to citrus trees. Both the Asian citrus psyllid and huanglongbing have been found in Southern California backyard citrus trees and threaten to spread throughout the state.

    Huanglongbing, also known as citrus greening disease, is a bacterial infection that stunts citrus trees, reduces their fruit production, deforms and greens the fruit and eventually kills the tree. There is no known cure or effective control.

    The disease has already devastated Florida’s citrus industry, slashing the state’s orange production by 92% between 2005 and 2025, according to Karen Jetter, associate director and project economist at the UC ANR Policy Institute. By the time the magnitude of the problem was revealed, both Asian citrus psyllid, or ACP, and huanglongbing were widespread in Florida.

    “In California, we still have the opportunity to slow the spread of huanglongbing through ACP management,” Jetter said.  “This unique technology is designed to be part of a comprehensive ACP management program, not to replace it.”

    Jetter and Fiona Ogunkoya, survey researcher at the UC ANR Policy Institute, are conducting focus groups to assess consumer attitudes toward an engineered Bt pest control method that targets Asian citrus psyllids, the primary vector of the disease, to stop the spread of huanglongbing.

    The bioengineered pest control strategy, developed in Florida and shown to be effective, uses an engineered citrus tristeza virus to transmit an engineered Bacillus thuringiensis to citrus trees. The Asian citrus psyllid lays eggs on the tender new leaf growth of the trees. After the nymphs hatch, the immature insects consume the modified Bt-infected leaves, become sick and die.

    California citrus growers surveyed by Sandipa Gautam, UC Cooperative Extension integrated pest management citrus advisor, said they are interested in the approach. But they growers are concerned that consumers will not accept fruit grown with this new bioengineered insecticide.

    To find out what consumers think, the researchers will meet with three focus groups, with each session limited to six to eight people to allow all participants time to express their thoughts.

    The 90-minute focus group meetings will be held at UC Cooperative Extension offices in Riverside on March 30 at 6 p.m., in Oakland on April 6 at 2 p.m. and in Fresno on April 8 at 2 p.m. Pizza will be served.

    To participate in a focus group, register for a session at https://forms.gle/QPyUd7QazTLfNdATA. To be eligible, participants must be 18 years of age or older and able to attend the focus group in person. — By UC Agriculture and Natural Resources

  • Using Predators to Counter Asian Citrus Psyllids

     

    The Asian citrus psyllid is an active threat for growers and the main vector for Huanglongbing disease. These invasive insects have wreaked havoc in Florida and spread to Southern California, but researchers at UC Riverside are finding ways to counter them. Matthew Malcolm from Malcolm Media Ag Publishing interviewed Bodil Cass at the World Ag Expo to discuss the use of predators against psyllids. Watch this quick video and read more in California Fruit & Vegetable Magazine.

    Please thank this video’s sponsor Simplot for their industry support.

  • UC Davis Professor Honored for Citrus Pest Research

    UC Davis Distinguished Professor Walter Leal recently received an award from the citrus research organization, FUNDECITRUS,  São Paulo, Brazil, in recognition of his “outstanding contribution to citriculture, emphasizing his work on the Asian citrus psyllid and a Lepidopteran pest named “bicho furão” (citrus fruit borer).

    Leal, a member of the Department of Molecular and Cellular Biology faculty and a former professor and chair of the UC Davis Department of Entomology, is the first U.S.-based researcher to receive the FUNDECITRUS. award.

    A native of Brazil and a Fellow of both the Entomological Society of America and the Entomological Society of Brazil, Leal is the principal investigator of a research agreement between UC Davis and the Fundecitrus-Fund for Protection of Citriculture, based in São Paulo.

    Leal’s discovery of the sex pheromone of the Asian citrus psyllid–which spreads the deadly citrus greening disease, Huanglongbing (HLB)–may result in the insect version of “The Fatal Attraction.” The team is now working on a formulation to be used in traps.

    The Asian citrus psyllid, Diaphorina citris, is a sap-sucking bug that is one of two confirmed vectors of HLB. A native of Asia, it is found in parts of the Middle East, South and Central America, Mexico, and the Caribbean. It was first detected in the United States in 1998 (Palm Beach County, Florida) and is now also found in Louisiana, Georgia, Arizona, South Carolina, Texas, and since 2003, in California  (San Joaquin Valley and Central Coast counties, including San Luis Obispo.)

    Former UC Cooperative Extension advisor Surendra Dara of San Luis Obispo and Santa Barbara counties (now at the University o Hawaii, Mānoa) earlier said that “The Asian citrus psyllid is a major threat to the multibillion dollar citrus industry in the United States. When an insect pest vectors a deadly disease, the threat is more serious and ACP being an invasive pest made its management even more challenging.  Discovery of a sex pheromone by Dr. Leal’s team is a major breakthrough not just for managing a dangerous invasive pest, but also a significant contribution to environmental sustainability.  I envision this pheromone becoming a clean, green, mean weapon in the IPM arsenal against ACP.”.

    Integrated pest management specialist and UC Davis Distinguished Professor Emeritus (on recall) Frank Zalom, of the UC Davis Department of Entomology and Nematology and a past president of the Entomological Society of America, earlier hailed the discovery as a “significant breakthrough in preventing the spread of this serious citrus insect, and may offer a less toxic method for its control.” He was not involved in the study.

    Pheromones and other semiochemicals are widely used in agriculture and medical entomology. “Growers use them as lures in trapping systems for monitoring and surveillance, as well as for strategies for controlling populations, such as mating disruption and attraction-and-kill systems,” Leal noted.

    ACP feeds on new leaf growth of oranges, lemons, mandarins, grapefruit and other citrus, as well as some related plants. Infected psyllids can transmit the bacterium Candidatus Liberibacter asiaticus, which causes the fatal citrus disease. An early symptom of HLB in citrus is the yellowing of leaves on an individual limb or in a sector of a tree’s canopy.

    Citrus trees infected with HLB usually die within five years, according to the UC Statewide Integrated Pest Management Program. There is no known cure. “The only way to protect trees is to prevent spread of the HLB pathogen in the first place, by controlling psyllid populations and removing and destroying any infected trees,” UC IPM says on its website.

  • “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