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)
- New and improved CDFA Citrus Division website: https://www.cdfa.ca.gov/Citrus/
- General ACP/HLB
o Information on the state ACP/HLB program including maps, quarantine information, and a signup option for email alerts: citrusinsider.org/
o Biology of ACP and HLB, detection maps and recommendations for monitoring, eradication and management: ucanr.edu/sites/acp/
o UC IPM recommendations for ACP
o Web-based map to find out how close you are to HLB: ucanr.edu/hlbgrowerapp
o Video on Best Practices in the Field, available in English and Spanish
o Summaries of the latest research to combat HLB: ucanr.edu/sites/scienceforcitrushealth/
o Science-based analyses to guide policy decisions, logistics, and operations: www.datoc.us
o Sign up for program updates from the Citrus Pest and Disease Prevention Division at www.cdfa/signup-email-updates.
o Regulatory requirements for moving bulk citrus: Information for Citrus Growers
o Summary of regulatory requirements in the event of an HLB detection in commercial citrus: citrusinsider.org/Regulatory-Flyer
New ‘Candidatus Liberibacter' Pathosystems Focus Issue from APS (American Phytopathological Society)
Read the great review of the bacteria that causes Citrus Huanglongbing and then the abstracts of the articles in this edition of Phytopathology. The review itself is pretty comprehensive, however you can't read the full articles contained in the editon without paying. But this gives you an idea of the extent of work being done, even though the language may be quite technical. The 18 articles in this Phytopathology Focus Issue showcase the enormous research efforts made by the scientific community, giving rise to major advances and achievements in a short time often through multidisciplinary approaches applied to the bacterium, psyllid vector, and plant host. Preview two editors' pick below or see the full Focus Issue.
Alves et al. explored Huanglongbing (HLB) presence and absence over 13 years in citrus orchards in Brazil and compared two hierarchical Bayesian modeling approaches to link climatic factors to the spatial distribution of HLB prevalence. They found an inverse relationship between HLB prevalence and mean temperature during the dry season, but wind speed, rainfall, and proximity of other HLB contributed to HLB prevalence. The results further our understanding of environmental factors associated with disease distribution and spread and assists policymakers in defining regions at risk of HLB outbreaks to help guide monitoring strategies that mitigate further spread of HLB.
A $1.5 million emergency grant is enabling UC Riverside scientists to find plants impervious to a disease threatening America's citrus fruit supply.
Citrus Greening Disease — also known as Huanglongbing, or HLB — results in fruit that is bitter and worthless. It has crippled Florida's citrus industry and has already been detected in California, which grows 80% of America's fresh citrus. An estimated 267,000 acres of Golden State oranges, lemons, grapefruits, and mandarins are at stake.
For these reasons, the National Institute of Food and Agriculture is supporting scientists at UCR, the University of Florida, and the U.S. Department of Agriculture's Agricultural Research Service in their search for plants with natural tolerance to HLB.
“If you find a disease affecting your crops, a good first step is to look for plants that are able to grow and produce despite infection,” said UCR geneticist Danelle Seymour. “Then you can start to identify the genetic basis of the disease tolerance and make sure the next generation of plants includes these genes.”
Following this recipe, Seymour and UCR plant pathologist Philippe Rolshausen will examine a set of 350 citrus hybrids developed and grown by project collaborators in Florida. All trees in the set are already infected with HLB, yet they live longer, are healthier, and yield more fruit than their infected relatives.
While there are a number of projects searching for different solutions to the threat of HLB, this project is different because the plants being tested were all grown in an environment endemic to the disease. Additionally, the number of plants they're able to test is unusually large.
“The environment in which these plants were grown means we can be confident that these rootstocks will enhance tree health and yield in HLB-affected areas,” Seymour said. “Also, because our data set is so large, we've got the opportunity to identify plants with levels of tolerance that exceed current commercial varieties.”
In addition to searching for parts of the hearty hybrids' genomes responsible for their tolerance to HLB, scientists will also be checking for plants that have resistance to other pathogens that are already in California.
Citrus in the state is also threatened by nematodes that chew up roots, preventing plants from taking up nutrients, and by phytophthora, a type of water mold that causes rotting roots.
By searching not only for a solution to the looming threat of HLB but also to problems that have already taken root in California, scientists are hoping to ensure that citrus won't need to be imported from HLB-free countries and costs stay low for both local growers and consumers.
“This way, we're making sure the next generation of rootstocks will include the right genes and that we're being as efficient as possible in our breeding practices,” Seymour said.
ACP nymph image by Sam Droege, USGS
As of November 5, a total of 2,619 trees and 368 ACP have tested positive via PCR for the bacterium that causes HLB. The most recent activity has been in Orange and San Bernardino counties. Infected trees have been or are being removed, additional HLB detection surveys and ACP treatments are applied on a recurring basis to remaining citrus in those areas.
For additional details, please see the updated HLB quarantine and treatment map and table at maps.cdfa.ca.gov/WeeklyACPMaps/HLBWeb/HLB_Treatments.pdf.
For information on regulatory and treatment requirements growers can expect should HLB be detected in or near your citrus grove or packing house, please refer to CDFA's Information for Citrus Growers/Grove Managers, Action Plan for ACP and HLB or this summary flyer.
Mustang Maxx has been approved for Spray and Harvest. For growers who harvest in one ACP Regional Quarantine Zone and pack in another, and use Spray and Harvest as their mitigation for moving bulk citrus, the list of approved ACP materials has been updated. The most recent list and protocols for quarantine compliance can always be found in the Information for Growers/Grove Managers document from CDFA. Please keep in mind this is separate and distinct from protocols and materials for Area Wide Management, discussed above.
Additional ACP/HLB Resources
- Check out the new and improved 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
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
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
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
Commercial Citrus – How will the citrus grower manage the pest and disease in commercial groves?
The deadly huanglongbing (HLB) is spreading in California and threatens commercial citrus production. This website provides a map of where the Asian citrus psyllid (ACP) and HLB disease are located. Since there is currently no cure for the disease, the best management strategy is reducing the psyllid vector with insecticides and removing HLB-infected trees. This website provides a list of the ACP-effective insecticides, information about the best timing of their use & strategies for treatment.
Residential Citrus – What should I do to protect the citrus in my yard?
There is currently no cure for the huanglongbing (HLB) disease that kills citrus trees and is spread by an insect, the Asian citrus psyllid. It is estimated that 60% of Californians have at least one citrus tree in their yard, meaning that HLB may have a devastating effect in residential areas of California. Currently the only way to control the disease is to reduce the psyllid that spreads it and to remove trees that are infected or located near known infections. This website provides information about how near the insect and disease are to your home, and what you can do to help protect your trees.
How can I help educate the public on this very important subject?
This site has important resources for you to use to teach others about Asian citrus psyllid and huanglongbing.
Watch the 4-minute video below to learn what you can do to help control Asian citrus psyllid & HLB
Authors of this website are Dr. Matt Daugherty and Dr. Beth Grafton-Cardwell (retired) Extension Specialists in the Department of Entomology, UC Riverside, and Robert Johnson with UC Agriculture & Natural Resources, Informatics & GIS Statewide Program