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LinkedInPosts Tagged: citrus HLB
Florida Research on HLB
Seven entities recently received $21.7 million to conduct research into combating and preventing HLB at the farm level. The funding is from the U.S. Department of Agriculture's National Institute of Food and Agriculture (USDA NIFA) Emergency Citrus Disease Research and Extension program.
(Photo by Tim Gottwald)
The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) received the majority of the funding, more than $16 million.
PROJECTS LED BY UF/IFAS
The largest grant, at approximately $8.6 million, is for development, evaluation and delivery of citrus HLB management approaches by targeting its nature as a pathogen-triggered immune disease. The principal investigator is Nian Wang. The goal is to develop HLB management approaches for existing groves and non-transgenic HLB-resistant and HLB-tolerant citrus varieties.
Other UF/IFAS projects are:
- A coordinated network for the improvement of HLB research and Extension outputs, funded at $2 million. Megan Dewdney is the principal investigator. The project tackles the task of gathering and organizing the research findings available to growers.
- Targeted production of non-transgenic HLB-tolerant trees through complementary approaches, funded at approximately $1.5 million. Zhonglin Mou is the principal investigator. The first goal of this project is to produce non-genetically modified HLB-tolerant citrus trees by editing or silencing the promising target genes.
- HLB-resistant rootstock candidates for the citrus industry: Validating and understanding disease resistance, funded at approximately $1.2 million. The principal investigator is John Chater. This project will advance knowledge about why some rootstocks appear to be more tolerant to HLB than others.
- Providing individual protective covers and brassinosteroids to prolong health and improve fruit yield and quality in newly planted trees, funded at $800,000. Fernando Alferez is the principal investigator.
- Toward a reliable insect cell culture-based technique for culturing CLas bacteria (the causative agent of HLB), funded at approximately $793,000. Kirsten Pelz-Stelinski is the principal investigator. The project aims to have a culture system that serves as an essential research tool for increased understanding of CLas biology and for effective, rapid screening of antimicrobial agents against CLas.
- Accelerating the delivery of conventionally developed HLB-tolerant citrus scions and rootstocks as pathogen-free budlines for replicate multi-site testing, funded at approximately $536,000. The principal investigator is Jude Grosser. Successful adoption of this technology will reduce the current clean-up time by 1.5 to 2 years, and significantly increase the number of selections that can be processed.
PROJECTS LED BY OTHER INSTITUTIONS
- Virus-induced gene silencing using insect specific viruses to manipulate psyllids as a strategy to control HLB is a University of California-Davis project led by Yen-Wen Kuo.
- A method for generating an optimally attractive scent for Asian citrus psyllid biocontrol is a University of Connecticut project led by Alexander Aksenov. UF/IFAS' Lukasz Stelinski is a co-investigator.
- Endophytes as sources of antimicrobials to control HLB is being led by Kateel Shetty of Florida International University.
- Scalable low-cost organic nanocarriers for efficient foliar uptake of registered anti-HLB agents is a Purdue University project led by Kurt Ristroph.
- Citrus yellow vein-associated virus induced gene silencing vector for vaccinating seedlings and controlling HLB in infected fruit-bearing trees is a University of Maryland project led by Anne Simon.
- Molecular strategies to block psyllid transmission of the HLB pathogen is a USDA Agricultural Research Service project led by Michelle Heck.
Sources: USDA NIFA and UF/IFAS
Deformed HLB-infected fruit
hlb defprmed citrus
ACP Updates
Asian Citrus Psyllid Update
Winter and spring rains have given us a robust growing season this year. Tender new citrus flush is ideal habitat for ACP to feed, lay eggs and build new populations. An increase in ACP numbers and feeding can increase the risk of HLB spreading and building up. University of California recommends growers monitor trees regularly for ACP, paying careful attention to new flush, and treat when populations reach the detection threshold. The UC IPM website lists a range of materials effective against ACP, including organic options. Growers are also encouraged to work with a pest management professional to better detect and manage ACP.
Advanced notification of nearby beekeepers is required before pesticide treatments. Use the BeeWhere BeeCheck system, or contact the County Agricultural Commissioner's office, 805-681-5600, for more information. Always follow label instructions for bee safety.
If your citrus is no longer being cared for or is not worth the resources required to protect it from ACP and HLB, consider removing it.
HLB Quarantine Update
As of May 5, a total of 5.007 trees and 709 ACP have been confirmed positive for the bacterium that causes HLB. Trees confirmed positive are treated for ACP and removed, and the HLB quarantine may be expanded. Additional ACP treatments and HLB detection surveys are conducted on a recurring basis to remaining citrus within 250 meters of each detection.
Counties where HLB has been detected via PCR testing are Los Angeles, Orange, San Diego, Riverside, San Bernardino and San Diego, with the majority of detections in Orange County. To see a map of the current HLB quarantine areas, and other details of locations and numbers of HLB detections, please visit maps.cdfa.ca.gov/WeeklyACPMaps/HLBWeb/HLB_Treatments.pdf.
HLB Detection Response Guide for Growers
To ensure California citrus growers are well prepared in the event of a potential commercial grove detection of Huanglongbing (HLB), the Citrus Pest and Disease Prevention Program (CPDPP) has developed the Response Guide for a Confirmed HLB Positive Detection in a Commercial Grove, which details the steps taken by CDFA and actions required of the property or grove owner, as outlined in CDFA's Action Plan and Information for Citrus Growers/Grove Managers.
Citrus Pest and Disease Prevention Committee Meetings -- Webinar and In Person
All meeting agendas and eventually the minutes are posted at www.cdfa.ca.gov/citrus committee/. The 2022-23 schedule for the Full Committee is here, and the schedule for Subcommittees is here.
Upcoming Meetings
- Operations Subcommittee, Wednesday May 10 at 9 am (agenda and webinar link)
- Outreach Subcommittee, Wednesday May 10 at 1:30 pm (agenda and webinar link)
- CPDPP Full Committee, Wednesday August 9 (agenda pending)
All meetings are free and open to the public to listen to or make public comment. Meetings are currently in person and accessible via phone and/or webinar. Links to register for and join meetings are included in agendas when posted.
For a list of current committee members, click here.
Additional ACP/HLB Resources
- CDFA Citrus Division website: https://www.cdfa.ca.gov/Citrus/
- General ACP/HLB
oInformation on the state ACP/HLB program including maps, quarantine information, and a signup option for email alerts: citrusinsider.org/
oBiology of ACP and HLB, detection maps and recommendations for monitoring, eradication and management: ucanr.edu/sites/acp/
oUC IPM recommendations for ACP insecticides
oWeb-based map to find out how close you are to HLB: ucanr.edu/hlbgrowerapp
oVideo on Best Practices in the Field, available in English and Spanish
oSpanish-only ACP/HLB presentation video presentation and audio-only recording.
- Research
oLatest Science Advisory Panel Report
oUC Ag Experts Talk presentations on management of various citrus pests and diseases are available for viewing here and here on YouTube.
oSummaries of the latest research to combat HLB: ucanr.edu/sites/scienceforcitrushealth/
oScience-based analyses to guide policy decisions, logistics, and operations: www.datoc.us
- Regulatory/Quarantine
oSign up for program updates from the Citrus Pest and Disease Prevention Division at www.cdfa/signup-email-updates.
oRegulatory requirements for moving bulk citrus: Information for Citrus Growers
oSummary of regulatory requirements in the event of an HLB detection in commercial citrus: citrusinsider.org/Regulatory-Flyer
oSanta Barbara County Ag Commissioner's Office
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Cressida Silvers
CA Citrus Pest and Disease Prevention Program
ACP/HLB Grower Liaison
Ventura, Santa Barbara and San Luis Obispo Counties
805 284-3310 (phone or text)
acp (2)
HLB Response Guidelines
New Educational Materials: 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.
Related
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.
Response Guide for a Confirmed HLB Positive Detection
ACP/HLB Updates from CPDPP
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acp nymphs and adults
Inarching for HLB Resistance
A recent article in Citrograph recounts studies in introducing tolerance/resistance to huanglongbing by inarching. This is a method that could potentially improve the productivity of trees that are already in the ground. This technique would reduce the huge demand on the nursery industry to supply the volumes of replacement trees that will be necessary when the ultimate scion/rootstock combinations tolerant to HLB have been identified.
Chandrika Ramadugu, Thomas G. McCollum, Joseph Patt and Mikeal L. Roose
Inarched tree with ‘Kuharske' rootstock, ‘Valencia' scion and ‘Orange
jasmine' inarch. After challenging with two HLB-positive bark patches, the plants
inarched with ‘Orange jasmine' were without HLB symptoms (Ct for ‘CLas was 35-38)
for six months. When the inarch was dislodged due to excessive growth of ‘Orange
jasmine,' the CLas titer increased (Ct 24).
Inarching (a second rootstock grafted onto the citrus scion generating a composite plant with two root systems) resistant plants to susceptible citrus scions was useful for mitigation of citrus sudden death disease prevalent in Brazil. If a similar approach can diminish HLB symptoms, it may provide a short-term disease management strategy for infected trees. With help from Brite Leaf citrus nursery in Florida, we generated a setof grafted plants with ‘Kuharske' rootstock and ‘Valencia' scion. These plants were then inarched above the bud union with small, rooted seedlings of four different non-citrus taxa previously determined to be resistant/tolerant to HLB. We monitored CLas titer and symptom development in the scion for disease scoring. The four plants used for inarching were: ‘Eremolemon,' 'Australian finger lime,' 'Large leaf Australian wild lime' and ‘Orange jasmine.' 'Eremolemon,' a naturally occurring hybrid of ‘Australian desert lime' and ‘Meyer lemon,' is resistant to HLB; on a disease scale of1-8, with 1 being immune and 8 being most susceptible (scoring is based on Ctvalues and symptom expression), ‘Eremolemon' scored a 2, a resistant response.Since ‘Eremolemon' produces nucellar seedlings that are identical to the mother plant, the progeny has only HLB-resistant individuals. ‘Australian Finger lime' and ‘Large leaf Australian wild lime' were considered HLB-tolerant with a score of 3.Seedlings from open-pollinated Microcitrus species growing in the Givaudan CitrusVariety Collection (where citrus and Microcitrus are growing in close proximity),are expected to have variable HLB disease response. ‘Orange jasmine' is resistant to CLas and has a disease score of 2; all the seedlings in the progeny show HLB resistance.
The experiment consisted of 108 inarched plants evaluated for up to one year in three locations – a research field and a greenhouse in Fort Pierce, Florida,and an organic grove in Clermont,Florida. The inarched plants were challenged with bark patches from a CLas-positive plant in the greenhouse. In the field, exposure to CLas was via psyllid feeding. Composite grafted plants inarched with ‘Eremolemon,'‘Australian Finger lime' and ‘Large leaf Australian wild lime' developed HLB symptoms indicating that these HLB-resistant or tolerant accessions did not impart this trait to the grafted plant.However, ‘Orange jasmine' used as an inarch did offer protection against CLas if the inarched stem was securely attached to the grafted plant. Out of 22plants inarched with ‘Orange jasmine,'20 showed low titers of CLas (Ct 35-38) and did not develop symptoms when the inarch was intact. However, due to the difference in the growth rates of citrus and ‘Orange jasmine,' the inarch was dislodged after a few months. We have modified the technique and are continuing experiments to confirm the ability of ‘Orange jasmine' to impart disease tolerance.
Preliminary results indicate that HLB-resistant ‘Orange jasmine' can impart tolerance to scions grafted on ‘Kuhaske' rootstock.
