The best way to delay arrival of HLB in our area and minimize its impact is to keep ACP suppressed down to the lowest level possible.  By treating in coordination with neighbors in an areawide approach, grower ACP treatments can have a greater impact on ACP populations than treating independently and out of sync with neighbors. Best Management Practices, such as making sure all equipment arriving and leaving your grove is free of citrus stems and leaves, can also greatly reduce the risk of HLB-positive psyllids entering your grove.

CITRUS REMOVAL PROGRAM: Citrus trees that are neglected or abandoned may harbor ACP and HLB, increasing risk to other citrus in the area. Abandoned and neglected trees may be reported to Cressida Silvers at 805-284-3310,  or the county Ag Commissioner's office. The Citrus Matters ACT NOW program may be able to assist in citrus removal. For more information contact Joel Reyes at  jreyes@cacitrusmutual.com or (559) 592-3790. 

Asian Citrus Psyllid / ACP

There have been no ACP detections in San Luis Obispo County since our last update.

Huanglongbing / HLB

The most recent map and totals for HLB detections are posted at the website https://citrusinsider.org/maps/. As of November 16, the total number of trees that have tested positive for the HLB bacterium is 948, still all in LA, Orange, and Riverside Counties. All HLB detections have been on residential properties and the infected trees have been or are being removed. No HLB has been found in commercial groves to date.

Clarification on Field Cleaning Requirements for Movement of Bulk Citrus

To clarify the approved mitigation measures for bulk citrus fruit movement, the California Department of Food and Agriculture (CDFA) has updated the Asian Citrus Psyllid (ACP)-Free Declaration form. The current options that allow growers to meet the ACP-free standard when shipping fruit to a different ACP regional quarantine zone are the “spray and harvest,” “field cleaning with machine” and “wet wash” methods. Field cleaning must be done by machine, not by hand.

To read the full article, click here: https://citrusinsider.org/2018/11/clarification-on-field-cleaning-requirements-for-movement-of-bulk-citrus/

Upcoming CPDPC Meetings

• Joint Science and Technology Subcommittee and Regulatory Task Force meeting Thur., December 6 at 1:30 pm in Sacramento. Agenda attached, including link to join by webinar/phone.
• CPDPC Operations Subcommittee meets Wed., December 12 at 9 am in Visalia. Agenda attached with link to join by webinar/phone.
• The next meeting of the CPDPC Full Committee will be January 9 in Visalia. Agenda is pending. 
• All meeting agendas and eventually the minutes are posted at https://www.cdfa.ca.gov/citruscommittee/ . All meetings are free and open to the public, and accessible via webinar.  

Additional Resources

• General information on the ACP/HLB program, including quarantine information: https://citrusinsider.org/
• Biology of ACP and HLB, detection maps and recommendations for monitoring, eradication and management : http://ucanr.edu/sites/acp/
• Summaries of the latest research to combat HLB: http://ucanr.edu/sites/scienceforcitrushealth/

And Now it's in Marin County

SACRAMENTO — Marin County has been placed under quarantine for the Asian citrus psyllid (ACP) following the detection of one ACP in the City of Novato. The entire county is included in the quarantine zone.

The ACP is an invasive species of concern because it can carry the disease huanglongbing (HLB), also known as citrus greening.  All citrus and closely related species, such as curry leaf trees, are susceptible hosts for both the insect and disease.  There is no cure once the tree becomes infected. A diseased tree will decline in health and produce bitter, misshaped fruit until it dies.  In California, HLB has been detected at residential properties in Los Angeles, Orange and Riverside counties. This plant disease does not affect human health.

Residents with backyard citrus trees in the quarantine area are asked not to transport or send citrus fruit or leaves, potted citrus trees, or curry leaves from the quarantine area. For commercial citrus, the quarantine prohibits the movement of citrus and curry leaf tree nursery stock, including all plant parts except fruit, out of the quarantine area. The quarantine also requires that all commercial citrus fruit be cleaned of leaves and stems prior to moving out of the quarantine area.  An exception may be made for nursery stock and budwood grown in USDA-approved structures that are designed to keep ACP and other insects out.

ACP quarantines are in place in Alameda, Contra Costa, Fresno, Kern, Kings, Madera, Merced, Monterey, Placer, San Benito, San Joaquin, San Luis Obispo, San Mateo, Santa Clara, Solano, Stanislaus, Tulare, Yolo, Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, and Ventura counties, as well as Marin.

Residents in the area who think they may have seen ACP or symptoms of HLB on their trees are urged to call CDFA's Pest Hotline at 1-800-491-1899 or a local agricultural commissioner's office  For more information on the ACP and HLB, please visit: www.cdfa.ca.gov/go/acp. Residents are also asked to follow these steps:

• Inspect trees for the Asian citrus psyllid and Huanglongbing monthly, and whenever watering, spraying, pruning or tending trees. Psyllids are most noticeable when new leaves are growing on the tips of the branches.
• As part of your tree care, visit your local nursery or garden center to get advice on products that can help protect your citrus tree.
• Do not move citrus plants, foliage or fruit into or out of your area, and especially across state or international borders. This could unknowingly contribute to spread of the pest and disease.
• When planting a new citrus tree, be sure to get your tree from a reputable, licensed nursery in your local area.
• When grafting citrus trees, only use registered budwood that comes with source documentation, such as the budwood offered through the Citrus Clonal Protection Program.
• Be sure to dry out citrus tree clippings or double bag them before removing the plant material from the property.

–California Department of Food and Agriculture

VISALIA – Last week's California Citrus Conference marked a major milestone for growers, and it wasn't just the 50th anniversary of the Visalia-based Citrus Research Board (CRB). It was a resounding revelation that new research may cure the greatest threat to the citrus industry in the next few years.

Michelle Heck, a molecular biologist with the USDA Agricultural Research Service, discusses her research to breed a new citrus pest that does not transmit the fatal tree disease known as huanglongbing. Photo by Michael Alvarez.

Michelle Heck, PhD, told the crowd of citrus growers at the Wyndham Hotel on Oct. 10 that her team might only need that much time to inbreed a generation of Asian citrus psyllids that are incapable of transmitting the deadly tree disease known as huanglongbing (HLB). The disease has already destroyed China's citrus industry, decimated Florida and Texas growing regions and is currently killing the citrus industry in Brazil.

One grower commented, “China's been dealing with this for 100 years and Brazil for 14 years. We've had this for four to five years in California and we are already knocking on the door of nailing it. That's impressive!”

Heck, a molecular biologist with the USDA Agricultural Research Service, was the first to lead a team of scientists to study the proteins involved in the interaction of the pest, plant and pathogen. One of those proteins creates a blue color in the blood of some psyllids. Her research revealed that psyllids containing the blue protein are far less efficient at transmitting HLB to the plant than others. She then bred those psyllids and took their progency and raised them on orange jasmine hedges, better known as Murraya, a plant the psyllids are attracted but is HLB resistant. The combination of the pest and plant reduced transmission of HLB to healthy citrus leaves from 32% to 2.9%.

Heck said the next steps are to continue breeding the pests that are poor transmitters of the disease to create a line of psyllids that do not transmit HLB at all. She said it would take another two years to breed an “optimized line” of the psyllid but once that was complete, that line could begin mass breeding for release.

“By sheer numbers, we can tip the scales [in the fight against HLB],” she said, “but it's unknown if these lines will out compete other psyllids [in the field].”

One grower asked if the non-transmitting line of the pest would be considered a genetically modified organism, or GMO, a distinction that could hurt fruit grown in groves with the new pest. Heck said all of the psyllids would be bred natuarally, so there is no genetic alteration of the insect itself.

“This is something the anti-GMO groups should feel good about,” Heck said.

Best Case Scenario

Victoria Hornbaker, Statewide Citrus Program Manager for the California Department of Food and Agriculture (CDFA), called the current HLB situation in California a best case scenario. She said the Citrus Pest and Disease Prevention Program's (CPDPP) No. 1 priority is to quickly detect and remove diseased trees. Shortly after the discovery of the first HLB tree in 2012, California's myriad of citrus agencies worked together to quickly implement measures to control movement of fruit and nursery stock, monitor and suppress the ACP population, and begin working on ways to detect the disease and possibly cure it.

“Instead of all commercial groves being covered by a quarantine, we said we're going to quarantine the whole state,” Hornbaker said.

By limiting the movement of citrus in and out of different quarantine zones, there is less likelihood of transporting trees from an infected area to an uninfected area. If any infected trees are discovered, they are removed, destroyed and replaced with a healthy tree. There are many early detection techniques (EDTs) being studied throughout the country, including looking for patterns in leaves, chemicals produced by trees in response to HLB, and studying molecules of the bacteria causing the disease. A recent analysis of these EDTs showed that most are about 95% effective in identifying an infected tree, and that losing 5% of healthy trees is an acceptable loss compared to devastation caused by the disease spreading unchecked.

While early detection methods of ACP are still being perfected, the fight to control the spread of the psyllid is not. After research identified the microscopic parasitic wasp radiate terminaxia as the natural enemy of the psyllid, they began working to mass produce and release them. To date, more than 11 million wasps have bee released in citrus growing regions since 2013, the closest being in Kern County.

Reproduced from Sun Gazette:

http://www.thesungazette.com/article/news/2018/10/17/pests-that-spread-citrus-disease-are-key-to-cure/

The city of Riverside pitched a white tent over the "Parent Navel" orange tree at the intersection of Arlington and Magnolia avenues last week to protect it from the threat of huanglongbing disease, reported Ryan Hagen the Riverside Press Enterprise.

“The Parent Navel is an iconic symbol of Riverside, as it represents the impact the citrus industry had on our economy,” Mayor Rusty Bailey said in a press release issued by the City of Riverside. “Riversiders hold this symbol of our citrus heritage very dear, so it is encouraging to see our parks personnel taking a proactive approach.”

The tree was one of two planted by Eliza Tibbets in 1873, when she received the seedless orange cultivars from Florida by mail. Tibbets cared for the trees and sold budwood to nurseries, which led to extensive plantings of nursery trees cloned from hers.

Huanglongbing disease made its appearance in Riverside last year in residential trees. Officials are working to prevent its spread by controlling Asian citrus psyllid, the insect that can move the disease from tree to tree. Meanwhile researchers are searching for a cure.

The Parent Navel's high value led UC Riverside researchers and city officials to construct the large white barrier.

"It's not beautiful," said Georgios Vidalakis, UC Cooperative Extension specialist and director of the citrus clonal protection program at UC Riverside. "It's obstructing the tree from public view, and we apologize for that. But the risk from not doing that is catastrophic."

The Riverside 'Parent Navel' orange tree is covered with a large white tent to protect it from Asian citrus psyllid, an invasive pest that can spread the devastating huanglongbing disease of citrus. (Photo: City of Riverside)

The Riverside 'Parent Navel' orange tree is covered with a large white tent to protect it from Asian citrus psyllid, an invasive pest that can spread the devastating huanglongbing disease of citrus. (Photo: City of Riverside)