Researchers from Sacramento State and the University of California, Riverside are requesting input from citrus industry members to help examine the economics of Asian citrus psyllid (ACP) and huanglongbing (HLB) management in California citrus groves.
The research team is looking for growers, advisors and other citrus industry members in California to provide input on overall knowledge of ACP and HLB, how they obtain information on the pest and disease, and how this might influence grove management practices. What is learned from this survey will help advance an economic analysis, contribute to overall understanding of ACP and HLB management, and improve the design and effectiveness of outreach and Extension resources to manage ACP and HLB.
If you are interested in providing input for forthcoming research, please complete the survey here.
This study is part of a U.S. Department of Agriculture Emergency Citrus Disease Research and Extension-funded project investigating microbial biocontrol to help in the fight against Candidatus Liberibacter asiaticus, the bacterium that causes HLB.
As the threat of HLB and ACP continue to put pressure on the commercial citrus industry, researchers across California are working to find the best treatments for this deadly disease. In a previous news release, Victoria Hornbaker, director of the Citrus Pest and Disease Prevention Division said that while these developments are promising to the future of the citrus industry, “It will take some time -- perhaps years -- before the potential treatment is on the market. In the meantime, it is important for industry members to remain vigilant in implementing best practices in the fight against huanglongbing and the Asian citrus psyllid.”
When answering survey questions, it is not necessary to look up records or calculate precise figures. The survey takes approximately 20 minutes to complete. All answers will be kept anonymous, and results will be presented in aggregate.
For questions about the survey or the research project, contact Jonathan Kaplan (firstname.lastname@example.org) at California State University, Sacramento.
Source: Citrus Pest & Disease Prevention Program
As of December 4, a total of 2,196 residential trees and 321 ACP have tested positive via PCR for the bacterium that causes HLB. See the latest HLB map and table for details: maps.cdfa.ca.gov/WeeklyACPMaps/HLBWeb/HLB_Treatments.pdf. As before, the infected trees have been or are being removed, and ACP treatments are applied on a recurring basis to remaining citrus in those areas. To date, no HLB has been found in commercial trees via PCR testing. The HLB quarantine area, however, includes commercial citrus and continues to expand.
Please refer to the CDFA Action Plan for ACP and HLB for information on regulatory and treatment requirements to expect should HLB be detected in or near your citrus grove or packing house.
Best Practices in the Field
In addition to monitoring and treating for ACP, another important way to protect your citrus from ACP and HLB is to follow Best Practices in the field, including insisting that all equipment, vehicles and bins be free of all plant material before entering your property.
Download or stream this video to help refresh field crews on the best practices for avoiding the spread of ACP and HLB during harvest.
- Sign up for program updates from the Citrus Pest and Disease Prevention Division at www.cdfa/signup-email-updates.
- General information on the state ACP/HLB program including maps, quarantine information, and a signup option for email alerts: citrusinsider.org/
- Biology of ACP and HLB, detection maps and recommendations for monitoring, eradication and management: ucanr.edu/sites/acp/
- UC Ag Experts Talk presentation "ACP for Commercial Growers and Pest Control Advisors", now available for viewing, along with other past talks on various citrus pests, at https://ucanr.edu/sites/ucexpertstalk/Past_Webinars/
- Web-based map to find out how close you are to HLB: ucanr.edu/hlbgrowerapp
- Summaries of the latest research to combat HLB: ucanr.edu/sites/scienceforcitrushealth/
- Science-based analyses to guide policy decisions, logistics, and operations: www.datoc.us
ACP trap detections have increased recently on the coast and in the Central Valley. While we usually see trap numbers peak this time of year, this fall the numbers have been higher than the last few years. Please stay vigilant in monitoring your trees for ACP, treating for ACP during the Area Wide Management treatment windows, and using an ACP-effective insecticide if possible when conducting other orchard management applications.
Map of HLB Quarantine and Treatment Area in California
Texas A&M AgriLife researchers have made a discovery that will help combat fastidious pathogens, which cost U.S. agriculture alone billions of dollars annually.
For the past few years, Kranthi Mandadi, Ph.D., a Texas A&M AgriLife Research scientist and associate professor in Texas A&M's Department of Plant Pathology and Microbiology, along with his colleagues, has been working on developing new biological technologies to fight fastidious or “unculturable” pathogens. Mandadi and members of his team are based at the Texas A&M AgriLife Research and Extension Center in Weslaco.
The results of their work, “Plant hairy roots enable high throughput identification of new antimicrobials against Candidatus Liberibacter spp.” were recently published in Nature Communications.
Fastidious plant diseases and their costs
Fastidious plant pathogens infect citrus, tomatoes, potatoes, grapes, peppers and other crops grown throughout Texas. Often transmitted by insect vectors, these disease agents cause billions of dollars of damage each year. The U.S. citrus industry alone would save $3 billion per year through control of just one of these diseases — citrus greening. Additionally, the fastidious pathogen that causes Pierce's Disease in grapes is the No.1 threat to the $1 billion wine industry in Texas.
“Currently, invasive fastidious pathogens are causing several major outbreaks in row crops, specialty crops and citrus, with immense costs to Texas and the U.S.,” said Juan Landivar, Ph.D., director of the AgriLife center at Weslaco, which has been involved in efforts to combat fastidious plant pathogens for many years.
Landivar said an expanded effort against fastidious plant diseases would protect the health of crops, environments, economies and people across the country.
A way to grow “unculturable” bacteria
Some plant pathogens can be grown as pure cultures in the laboratory in the presence of artificial nutrient solutions. Being able to culture disease agents in the lab facilitates their study by providing researchers with a reliable supply of experimental material. However, an estimated 99% of bacteria in the world are fastidious, or unable to grow outside their native environment.
“The greatest obstacle to understanding and controlling fastidious pathogens was the inability to cultivate them in a laboratory setting and to screen for lots of potential therapies,” said Leland “Sandy” Pierson, Ph.D., professor and head of Texas A&M's Department of Plant Pathology and Microbiology. “But Dr. Mandadi and his team have developed a breakthrough method as an alternative means to propagate fastidious bacteria. These bacteria are believed to be responsible for Huanglongbing, also known as citrus greening disease, and other insect-vectored diseases such as potato zebra chip and tomato vein greening disease.”
The breakthrough came in the form of the “hairy root” system. This technology utilizes the pathogen-infected host tissues to produce so-called hairy roots that can serve as biological vessels for the propagation of these pathogens in the laboratory.
“Classical microbiological techniques developed early in the 19th century cultured animal and mammalian viruses in host cells, tissues and embryonated eggs,” Mandadi said. “In a similar manner, we hypothesized that plant hairy roots could be suitable for propagating fastidious pathogens. And indeed, hairy roots supported the accumulation and growth of fastidious plant bacteria.”
Microbial hairy roots appear similar to normal root tissues that develop from the plant and mimic a bacterium's natural environment, he said. This allows the growth of the fastidious pathogens in controlled laboratory conditions.
Expedited screening for antimicrobial treatments
While microbial hairy root cultures are not traditional “pure” test tube cultures, they allow on-demand access to the fastidious bacterium in the laboratory. This enables the expedited screening of diverse antimicrobials like chemical inhibitors, immune modulators as well as gene/CRISPR-based therapies.
Other advantages are that hairy root cultures are easy to produce in the laboratory and can be maintained for several months to a year in laboratory growth chambers. Depending on the pathogen and the efficacy of screening, it is also at least four times faster than conventional screening methods, according to Sonia Irigoyen, Ph.D., and Manikandan Ramasamy, Ph.D., both AgriLife Research scientists and co-authors of the study.
In addition, the hairy root bioassays are scalable, so they can be used to pre-screen from a few to several hundred potential therapies simultaneously in a high-throughput manner. The microbial hairy root system can also be used to obtain mechanistic insights into antimicrobial function.
“Use of this technique has already led to the discovery of six new antimicrobial peptides with proven efficacy in plant materials,” Mandadi said. “These antimicrobials, either singly or in combination, could be used as near- and long-term therapies to control citrus greening, potato zebra chip and tomato vein greening diseases.”
Collaborators in the fight
“Typically, the type of breakthrough Dr. Mandadi and his team came up with is unusual for a university system off-campus center, as such centers usually have limited personnel and resources,” Landivar said. “Fortunately, the support we have received from the Texas A&M University System and other funding agencies and collaborators has helped make it possible for the Weslaco center to perform this world-class-level research.”
Besides a team of researchers at the Weslaco center, Mandadi collaborates with scientists at Texas A&M University, Texas A&M University Kingsville-Citrus Center, University of Florida, University of California System, and industry stakeholders including Citrus Research and Development Foundation, Texas Citrus Pest and Disease Management Corporation, Bayer and other entities.
Southern Gardens Citrus, a subsidiary of U.S. Sugar in Florida, has partnered with Texas A&M to commercialize the hairy root system as well as new therapies for application in the field.
Landivar also said funding from the U.S. Department of Agriculture National Institute of Food and Agriculture's Emergency Citrus Disease Research and Extension program, NIFA ECDRE, and support from the Foundation for Food and Agricultural Research and AgriLife Research's Insect-Vectored Disease Grant are making it possible to facilitate development of innovative technologies and discovery of therapies to combat diseases caused by fastidious bacteria.
To expand on his research, Mandadi recently partnered on a new project with Citrus Research and Development Foundation, Bayer, Southern Gardens Citrus, University of Florida and University of California-Davis. That project is funded by the NIFA ECDRE program. The overall goal is to bring together academics, growers and agrochemical industry to discover, develop and commercialize therapies for citrus greening disease.
Mandadi said use of the hairy root system has already been instrumental in finding several potential new treatments for citrus greening and potato zebra chip, as described in the Nature Communications article.
“We hope this technology can be further expanded to find even more therapies against current and emerging fastidious pathogens and, ultimately, with the support of industry, deploy them as field-ready products,” he said.
A recent Ventura County ACP-HLB Task Force sponsored webinar was held, the topics and speakers listed below The PDF's from the speakers are available online
Webinar Agenda 8-13-20
Welcome, and update on status of HLB in California:
Leslie Leavens, chair, Ventura County ACP-HLB Task Force.
Update on area-wide participation rates and CDFA buffer treatments:
Sandra Zwaal, Ventura County Grower Liaison
Final report on 2017-2020 ACP surveying project in Ventura County, and overview of Phase Two research:
Beth Grafton-Cardwell, IPM Specialist and Research Entomologist, University of California-Riverside, and Director of Lindcove Research and Extension Center (retired); and Monique Rivera, Assistant Extension Specialist, Department of Entomology, UC Riverside.
Final report on deployment of detection canines to scout Ventura County commercial groves for evidence of early HLB infection:
John Krist, CEO, Farm Bureau of Ventura County.
Implications of canine detection data for HLB management in Ventura County commercial citrus:
Neil McRoberts, western regional director, National Plant Diagnostic Network, and professor of plant pathology, UC Davis.
For more information, contact us by email at email@example.com.
Last week, UCR issued a news release entitled UCR Discovers First Effective Treatment for Citrus-destroying Disease, which shares the news of a licensing agreement being reached with Invaio Sciences. This is extremely exciting news about potentially promising research that could significantly change the future of the citrus industry, both here and in all citrus growing area in the world. Now it will be important to complete studies on the effectiveness of this therapy in greenhouse and field studies.
As yet, there are no published scientific papers describing the methodology by which they discovered it, or the field or lab trials through which they determined its efficacy. As has been the case so often with ACP-HLB, there have been promising strategies that on further inspection fail to meet the criteria of a “cure”.
If it really works in a commercial field setting, it would be a great complement to the canine surveys, since it would be much easier to clear infection from a tree when it is still in the early stages and has not yet become systemic.
The Citrus Research Board has a wait-and-see approach - Glad that something is in the works to be commercialized, but waiting for more test results. This might be a real breakthrough. Read the CRB's response to the recent news: