Western tree nut commodities just got through a very tough season, and markets are still less than ideal. The last thing growers want to hear about is a new pest threatening their orchard production. But the Carpophilus Beetle has already been under the radar far too long, damaging Central Valley orchards under the guise of “Navel Orangeworm.” Watch this brief video with Bob Klein from the California Pistachio Research Board as he explains, and read more about this new pest in the December and January issues of Pacific Nut Producer magazine.
The California Citrus Research Board (CRB) and the Conference Steering Committee are pleased to share the International Research Conference on Huanglongbing VII (IRCHLB VII) will return March 26-29, 2024, to Riverside, California.
The Conference is being produced by the CRB with the support of California’s citrus industry partners and guidance of the international Steering Committee. The California citrus industry is excited to welcome researchers, regulators, and citrus industry members from around the world to the Golden State. The Conference was previously held in Riverside in 2019 and welcomed more than 500 attendees, representing over 22 countries.
The IRCHLB VII will feature presentations and poster sessions detailing the global status of Huanglongbing (HLB), highlight ongoing research efforts, and share how research can move toward field solutions. A select group of keynote speakers will provide insight on innovative HLB research with a variety of perspectives and methodologies, including both domestic and international approaches.
HLB has affected hundreds of thousands of citrus trees in Florida and around the world and continues to be one of the biggest threats facing California’s citrus industry.
“It has been nearly four years since the HLB research community has met to discuss their findings on strategies to manage the devastating effects of citrus greening disease,” said MaryLou Polek, Ph.D., Chair of the IRCHLB Steering Committee. “I am looking forward to the IRCHLB VII to hear about research progress made by scientists from around the world.”
Registration for the conference is now open and additional information can be found at www.irchlb.com. The early bird registration rate of $425 is available through December 31, 2023 and will increase to the regular registration rate of $550 on January 1, 2024.
About the IRCHLB VII Conference
The International Research Conference on Huanglongbing VII is organized by the Citrus Research Board in collaboration with numerous citrus industry, state and federal government, and university partners. Learn more at www.irchlb.com.
About the Citrus Research Board
The Citrus Research Board administers the California Citrus Research Program, the grower-funded and grower-directed program established in 1968 enabling the state’s citrus producers to sponsor and support needed research. More information about the Citrus Research Board may be found at www.citrusresearch.org.
Pest Control Advisers (PCAs) in California are some of the brightest and versatile in the nation. They each generally cover a wide spectrum of crops grown under a many different conditions and pest challenges. Watch this brief interview with Ruthann Anderson, President and CEO of the California Association of Pest Control Advisers, as she discusses the current State of the California Pest Control Adviser, as well as an opportunity for PCAs and their growers to get grant funding to tell their IPM stories. Learn more and apply at: https://capca.com/memberships/#study
Effective Nov. 22, 2023, the Citrus Pest and Disease Prevention Division (CPDPD) has officially updated the requirements for moving bulk citrus fruit within and from a Huanglongbing (HLB) quarantine area to a packer/processor.
If you are moving bulk citrus within a contiguous HLB quarantine zone, there is now no mitigation required.
If you are moving bulk citrus within a contiguous HLB quarantine area, but out of the original ACP regional quarantine zone (i.e., Orange County to Riverside County), one HLB mitigation is required.
If you are moving bulk citrus between two non-contiguous HLB quarantine zones (i.e., Riverside County to Ventura County), there is now one HLB mitigation required.
If you are moving bulk citrus outside of an HLB quarantine area, but within the same county (i.e., San Diego HLB quarantine zone to San Diego ACP regional quarantine zone), there is one HLB mitigation required.
If you are moving bulk citrus fruit to an area outside of the HLB quarantine zone and outside of the origin county (i.e., Ventura HLB quarantine Zone to Kern County), two HLB mitigations or a wet wash are required.All fruit, no matter of its origin or destination, must be completely safeguarded with a tarp or enclosed vehicle while in transit per requirements listed in the compliance agreement. The CPDPD will be signing revised compliance agreements with growers within an HLB quarantine, as well as packers/processors receiving fruit from a quarantined area.For complete information and details regarding the mitigations required for fruit movement, please visit the CPDPD’s Citrus Grower/Grove Manager Information page.
For questions regarding citrus fruit movement requirements, please contact your local agricultural commissioner, email Keith Okasaki at Keith.Okasaki@cdfa.ca.gov or call 916-274-6300. — By the California Citrus Pest & Disease Prevention Program
The California Department of Pesticide Regulation (DPR) has asked a Kern County judge to halt pesticide applications by a Bakersfield-area aerial pesticide business accused of several illegal drift incidents that harmed at least one person and damaged property. Defendants in the complaint, filed on Sept. 29, include John A. Slykerman and his company, Agra Fly Inc.
DPR is seeking a court order barring Slykerman from conducting aerial pesticide applications. It also seeks various civil penalties.
“The California Department of Pesticide Regulation is taking immediate action against Slykerman and Agra Fly for their repeated illegal actions that have injured people and property,” said DPR Assistant Director Ken Everett. “DPR’s quick action is needed to prevent further egregious violations.”
The complaint focuses on six separate alleged drift incidents. In each case, the complaint says, the drift was a violation of both pesticide label requirements and California regulations. In addition, the complaint notes Slykerman does not have a current FAA-approved medical certificate, which is required to aerially apply pesticides.
The agricultural commissioners’ offices in Kern and Tulare counties investigated Slykerman’s drift violations and sought DPR’s collaboration to bring a coordinated enforcement action. California’s 55 agricultural commissioners investigate pesticide violations and partner with DPR to enforce pesticide use laws and regulations.
“We take drift incidents very seriously and immediately investigate them,” said Tulare County Agricultural Commissioner Tom Tucker. “Our investigators work closely with DPR to enforce our state laws and pesticide use requirements that keep Californians safe.”
Incidents of damaging drift alleged in the complaint include:
Arvin/Lamont Drift. On Sept. 2, 2023, Slykerman and Agra Fly were involved in a drift incident near the Kern County communities of Arvin and Lamont. The pesticide was being applied to an almond orchard and reportedly drifted onto people and property nearby. The investigation is ongoing.
Shafter Drift. On May 11, 2023, Slykerman was aerially applying pesticides to a cherry orchard near Shafter. The Kern County agricultural commissioner received a complaint that pesticides from the application had drifted onto a neighboring property. The Kern County agricultural commissioner investigated the incident and issued a fine to Agra Fly.
Lindsay Road Drift. On March 31, 2023, Slykerman was aerially applying pesticides to a field near Lindsay Road, south of Bakersfield. The Kern County agricultural commissioner received a complaint that pesticides from the application had drifted onto a neighboring property and onto a person. The Kern County agricultural commissioner investigated the incident and issued a fine to Agra Fly.
Porterville Drift. On Jan. 23, 2023, Slykerman was aerially applying pesticides to an orange orchard near Porterville, southeast of Tulare. The pesticides reportedly drifted onto a nearby field and person, who reported symptoms of pesticide exposure including burning sensation on skin and nausea. The property owner’s tangerine trees were also reportedly damaged.
Famoso Hills Drive Drift. On Jan. 21, 2023, a pilot was applying pesticides near Famoso Hills Drive, north of Bakersfield. The pesticide drifted onto nearby pastureland, damaging it. The Kern County Agricultural Commissioner’s Office investigated and issued fines to both Slykerman and Agra Fly.
Bear Mountain Boulevard Drift. On Sept. 24, 2022, a pilot associated with Agra Fly was applying pesticides near Bear Mountain Boulevard, south of Bakersfield. An investigation by the Kern County Agricultural Commissioner’s Office found that a pesticide drifted onto a nearby pistachio site, damaging the trees.
“Defendants’ activities are a public nuisance that endanger the life, well-being and property of the community around their applications. Each day that Defendants conduct aerial pesticide applications, the significant threat to the community exists,” the complaint states, urging the court’s intervention.
For more information, you can read a copy of the complaint on DPR’s website.
ABOUT THE DEPARTMENT OF PESTICIDE REGULATION
The California Department of Pesticide Regulation’s mission is to protect human health and the environment by fostering safer and sustainable pest management practices and operating a robust regulatory system to monitor and manage the sale and use of pesticides across the state. DPR’s work includes registering all pesticides sold or used in California, conducting scientific evaluation of pesticides to assess and mitigate potential harm to human health or the environment, monitoring for pesticides in the air and water, and enforcing pesticide regulations in coordination with 55 County Agriculture Commissioners and their 500 field inspectors. DPR also conducts outreach to ensure pesticide workers, farmworkers and local communities have access to safety information. DPR invests in innovative research to encourage the development and adoption of integrated pest management tools and practices. More information about DPR can be found at www.cdpr.ca.gov.
Conversion to Biofuels Good for Air Quality and Climate Policies
As California works to meet climate and air quality goals, a key to the transition will come from biomass, which is renewable organic material from plants and animals.
New research from the University of California, Davis, published in the journal Global Change Biology Bioenergy, examines the good and bad uses of biomass and the best pathways to meet California’s goal of reducing carbon dioxide emissions by 85% of 1990 levels by 2045.
“California is fortunate in having a large biomass resource,” said lead author Peter Freer-Smith, an adjunct professor in the Department of Plant Sciences. “Finding the best use of biomass remains challenging, and this study outlines future scenarios for effective use.”
Not all biomass is equal
California’s biomass resources are vast and widespread across the state, with as much as 54 million dry tons available each year. This comes mostly from forests and wildlands, municipal solid waste, animal manure and crop residues such as material left over from harvest.
But use of this biomass is controversial, and not all biomass is equal. Using this resource effectively to produce energy, as well as minimize greenhouse gas emissions and air pollution is key to a sustainable future for California.
Policymakers, planners and others working to reduce waste streams and pollutants should use the study as a resource, said Freer-Smith.
“Using this information, we can take action to ensure that biomass is used effectively in California,” he said. “If you’ve got a bad use, then you can use biomass in a different way, or you can change the technology so that you address the problems associated with that use. Also, some biomass is waste, so we have to get rid of it, and we might as well do something sensible with it.”
Freer-Smith and other researchers examined more than 400 papers written from 2005 to 2022 about biomass use in California and cataloged the effects on emissions.
Choosing the right path for biomass
The paper finds that there are 34 pathways that either help reduce greenhouse gases or specific air pollutants, and 14 that achieve reductions in both categories. Conversely, 13 pathways — including wildfires, the open burning of biomass and other uses — increase harmful emissions.
Good uses of biomass include combustion to generate renewable energy, producing biodiesel and converting wastes to biogas. Anaerobic digesters, which break down biodegradable materials into energy, have positive effects when it comes to converting agricultural, livestock, food and water waste.
Bad pathways include fires, open composting of animal manure and disposal of municipal solid waste without production of landfill gas. Wildfires have among the most negative effects.
Burning of forest material, such as for prescribed burns, and crop byproducts is also detrimental.
“It would be a lot better to take that down to the power station and burn it to create energy,” Freer-Smith said. “Even burning biomass in power stations is better for climate policy, and it’s better for air quality relative to burning on site.”
The paper also finds that new, innovative pathways are being developed to replace fossil fuels, meet climate objectives and contribute to the bioeconomy.
“It’s best to use biomass for renewable energy or for generating electricity where combustion is controlled and carbon capture becomes a possibility — so it’s better for climate policy and for air quality relative to burning on site,” said Freer-Smith. “Similarly, it’s important to get prescribed burning of forest biomass right.”
Jack H. Bailey-Bale, Caspar L. Donnison and Gail Taylor from the UC Davis Department of Plant Sciences contributed to the research.
Funding for the preliminary analysis came from the California Air Resources Board. The John B. Orr Endowment in Environmental Plant Sciences and the Center for Bioenergy Innovation at Oak Ridge National Laboratory also supported the research. — By Emily C. Dooley, UC Davis
The California Department of Food and Agriculture (CDFA) has declared a quarantine in Ventura County following the detection of the citrus disease Huanglongbing (HLB), or citrus greening, in two citrus trees on one residential property in the city of Santa Paula. These detections are the first HLB-positive trees in Ventura County. CDFA is working with the United States Department of Agriculture and the Ventura County Agricultural Commissioner on this cooperative project.
CDFA crews will be working to remove and dispose of the infected trees and are conducting a mandatory survey of every property within 250 meters of the detection site. After the survey is complete, all host plants in the 250-meter area around the detection site will be treated to suppress the disease vector, the ACP. By taking these steps, a critical reservoir of the disease and its vectors will be removed, which is essential to protect the surrounding citrus from this deadly disease.
These detections establish a mandatory five-mile citrus HLB quarantine area around the find site. The quarantine area is bordered on the north by Ojai Road; on the south by E Los Angeles Avenue; on the west by Wells Road; and on the east by Balcom Canyon Road. The quarantine prohibits the sale of all host nursery stock and the movement of all host plants or plant parts within a five-mile radius of the finds. The quarantine applies to residents and commercial operations alike. These detections will also place parts of Ventura County into Bulk Citrus Regional Quarantine Zone 6, which will require any commercial citrus growers to apply an additional mitigation step(s) to move fruit within or from this zone. Production and retail nurseries within the five-mile quarantine are being contacted by CDFA and will be issued a hold notice preventing the sale of nursery stock host plants. Visit CDFA’s Map and Quarantines page for more details.
Growers in Ventura County should contact Grower Liaisons Sandra Zwaal at szwaal2@gmail.com or Cressida Silvers at cressidasb@gmail.com for additional information about these detections. In response to the HLB detections in Santa Paula, a grower meeting was held on Wednesday, Oct. 4. Stay tuned to Citrus Insider for details or reach out to the Grower Liaisons for more information.
An HLB quarantine area currently exists in parts of Los Angeles, Orange, Riverside, San Bernardino and San Diego counties, where more than 6,300 residential trees have tested positive for the disease and have been removed. — California Citrus Pest & Disease Prevention Program
Leptospirosis is a serious zoonotic disease that affects both animals and humans. This bacterial disease is commonly spread through the urine of infected animals and rodents, including wildlife and livestock such as cattle and swine. Humans can contract leptospirosis by having contact with water (such as by swimming, rafting, or kayaking) or soil that has been contaminated by urine or body fluids of infected animals. Although this disease if often spread through urine, transmission can also occur in the genital tract of domestic animals.
Humans who contract leptospirosis may suffer from a range of symptoms, from a mild fever to massive pulmonary hemorrhage. For livestock, the disease can result in poor milk yield, reproductive failure, and in some cases, severe acute disease, especially for dairy and beef herds.
Scanning electron micrograph of a leptospire.
“Leptospirosis is caused by a very unusual and unique bacteria,” said Jarlath Nally, research microbiologist at the National Animal Disease Center (NADC) in Ames, IA. “Very few people work on it, the diagnostics are limited, and research is challenging because the bacteria that causes the disease are very difficult to grow in the lab.”
Leptospirosis is not a new disease; it was first described in 1886. Globally, the disease kills over 50,000 people a year and infects over one million. The Centers for Disease Control and Prevention described it as the most widespread zoonotic disease geographically.
Human infections can be treated with antibiotics, but the condition is considered rare in humans and can be difficult to diagnose. Vaccines have been developed for livestock, including dairy and beef herds. However, the vaccine protects only against specific variants of Leptospira, the bacteria that causes leptospirosis, and protection dwindles after one year. There are more than 38 species and hundreds of serovars of pathogenic Leptospira.
“It gets complicated because there are so many variants of this disease” said Nally. “And the vaccines being used today are based on variants isolated over 30 years ago.”
Detection is also a problem. Infected animals often appear asymptomatic. Stakeholders may not be aware that their herd is infected until they notice an increase in abortions or reproductive failures. Further complicating matters are the diagnostic tests, which are not always accurate.
ARS researchers Ellie Putz and Luis Fernandes working to elucidate pathogenic mechanism of leptospirosis.
“We’ve done a lot of work to improve diagnostics,” said Nally, “but there are limitations, and stakeholders need to be aware of that.”
Nally and his research partners are looking to improve diagnostics, testing, and current vaccine strategies to provide cross protection against multiple variants of Leptospira. To date, they have generated a large repository of isolates of Leptospira from a range of domestic (cows, bulls, horses and dogs), wildlife (rats, mice, mongoose, red panda), and environmental sources (soil, water), including new species and serovars detected for the first time in the U.S. They also created a new growth media that allows researchers to isolate the Leptospira bacteria directly from infected animal tissue at 37 degrees Celsius. This is an improvement over the old methods where Leptospira were previously restricted to isolation at 28-30 degrees Celsius.
“That’s a temperature more in line with standard laboratory processes,” Nally said. “But more importantly, it’s an environmental condition that’s more similar to the host.”
Researchers have also been able to genetically manipulate the bacteria, allowing them for the first time to identify, target, and silence certain genes.
“Not only silence a single gene, but we can actually silence two genes at the same time,” said Nally. “We were able to apply our technology to silence two similar genes to actually identify a virulence factor, rendering the bacteria completely attenuated, which provides new avenues to generate vaccines and apply it to different variants.”
Next steps for Nally and his research team are to map complete genotypes, complete serotypes, and identify virulence factors that facilitate the disease process. At the same time, they want to identify which variants are circulating in domestic and wildlife animal populations in the U.S.
“We are also interested in understanding how the disease occurs,” he said. “We are looking to understand why these bacteria are colonizing in the genital tract and why they’re associated with reproductive failure versus strains that are associated with more severe acute disease. To understand the ‘how’ will help us develop vaccines that will cross protect against all the variants that are out there.” — By Todd Silver, USDA-ARS Office of Communications
Damage from a sudden autumn freeze can occur when trees experience freezing temperatures prior to going into dormancy. With sudden autumn freeze damage occurring in three of the last five years, preparing for these freeze events needs to be a regular part of every walnut grower’s summer and fall orchard operations. The best approach to escape damage from a fall freeze is to have frost alarms ready and turned on by October 15, completely rehydrate trees after harvest, and actively irrigate during frost events.
Left: Withhold irrigation until a terminal vegetative bud sets on the trunk. Right: After a severe freeze event cut into the southwest-facing trunk, looking for dark brown discoloration of the cambium. (Photos: Janine Hasey)
Steps to prepare:
Tender new growth is most vulnerable to freeze damage: prevent trees from pushing late-season growth by cutting off N applications by mid-August (young trees) or early September (mature trees).
For young trees, withhold irrigation starting in early to mid-September, waiting to resume irrigation until after a terminal bud (left photo) is set on the trunk. After the terminal bud has set, resume irrigation to avoid tree stress and defoliation. For bearing trees, terminal buds usually set as a side effect of the water cutoff done ahead of harvest.
Keep groundcovers cut to 2 inches or less starting in mid-October. This allows sunlight to reach the soil surface, storing heat for a warmer orchard through the night.
Rehydrate trees immediately after harvest, and actively monitor soil moisture and freeze predictions (usually from mid-October through December) until trees are acclimated to frost (see note below). Trees with adequate soil moisture are better able to withstand low temperatures without damage than trees in dry soil. This is because water-filled spaces in the soil conduct and store more heat than empty airspaces. If a freeze is predicted and the soil is dry, it should ideally be wetted 2 to 3 days before a freeze event. Light irrigation to moisten a dry soil surface the morning before a frost will help obtain the greatest heat storage for re-radiation at night (if there is no ponding going into the freeze event).
Some growers with the ability to actively irrigate during sudden autumn freeze events have reported great success in preventing damage. We know from work in almonds that active frost protection can achieve as much as 4 degrees of warming with solid set, 1-2 degrees with micro-sprinkler, and maybe even some benefit running a drip system.
When do you no longer have to worry about preparing for the next freeze?
Fully dormant mature healthy trees can tolerate temperatures to the low 20’s (°F) or below. We believe walnuts acclimate by having the first mild frost events in autumn with lows near or just below 32° F. However, we do not know how many mild freezes are required to acclimate trees in autumn. If the soil is dry ahead of the third, fourth, and maybe additional freeze events – it’s better to irrigate and be safe if you can do so. In addition, consider keeping up your freeze response program longer into fall or early winter for younger orchards with lots of current season’s growth.
If you suspect freeze damage occurred, cut into the branches shortly after the freeze event and check the tissue for drying or browning (right photo). Sunburn after freeze can further damage tissue on the southwest side of the tree. Paint the southwest side of damaged trees with 50% diluted (1:1 water to paint) white interior latex paint. Painting up to a week after the freeze event can reduce additional damage by half or more. You can learn more about freeze recovery in our article 2020 Walnut Freeze: Road to Recovery.
— By Luke Milliron, UCCE Farm Advisor Butte, Glenn, and Tehama Counties; Jaime Ott, Orchard Systems Advisor, Tehama, Shasta, Glenn, and Butte Counties; Janine Hasey, UCCE Farm Advisor Emerita; and Joe Connell, UCCE Farm Advisor Emeritus
Citrus Pest & Disease Prevention Program — A Candidatus Liberibacter asiaticus (CLas)-positive Asian citrus psyllid (ACP) sample has been collected from a residential property in Ventura County in the Santa Paula area and has been confirmed by the Citrus Research Board’s Jerry Dimitman Laboratory. The positive sample – comprised of 12 adult psyllids from a residential citrus tree in the Southwest area of Santa Paula – was collected on Sept. 6 as part of the Multi-Pest Risk Survey and confirmed positive for CLas on Sept. 19. This is the first confirmed CLas-positive ACP found in Ventura County.
A Huanglongbing (HLB) quarantine zone will not be established as a result of this CLas-positive ACP detection and California Department of Food and Agriculture (CDFA) staff are swiftly conducting surveys and collecting samples from the property and all HLB host plants that are located within a 250-meter radius around the find, per the ACP/HLB Action Plan.
While the first confirmation of a CLas-positive ACP in Ventura County is concerning, as of today, HLB has not been detected in any Ventura County citrus trees. However, it is more crucial than ever that populations of the ACP continue to be controlled properly in order to stop the disease from spreading, as oftentimes a CLas-positive ACP precedes the detection of an HLB-positive tree. Additionally, there were no nymphs observed at the time of collection on Sept. 6., however, during resampling efforts this week, CDFA collected 15 nymphs from the find site property but on a different host plant. CDFA crews will be surveying for any additional adult or nymph psyllids as part of the 250-meter survey being conducted this week.
This CLas-positive ACP detection is not associated with the research that was conducted last year in Southern California – including Ventura County – as a part of a program funded by the HLB Multi Agency Coordination Group by researchers from UC Agriculture and Natural Resources, UC Davis, UC Riverside and the University of Arizona, Tucson. These studies’ laboratory tests vary from the federally approved testing methods and procedures required by CDFA labs that would allow the state to take any regulatory action. Therefore, this is the first CLas-positive ACP detection recognized by CDFA.
While treatment is not mandatory for area commercial growers as a result of the detection, Ventura County commercial growers who wish to take proactive steps to protecting their groves or who have additional questions can contact Ventura County Grower Liaisons Sandra Zwaal or Cressida Silvers.
The California Citrus Research Board (CRB) and the Conference Steering Committee are pleased to share the International Research Conference on Huanglongbing VII (IRCHLB VII) will return March 26-29, 2024, to Riverside, California.
For complete information and details regarding the mitigations required for fruit movement, please visit the 
