You’re invited to the California Olive IPM Workshop on September 18 from 8:00 a.m.–12:00 p.m. at the California Olive Ranch in Artois, CA. This free, hands-on field day is organized by the Center for Regenerative Agriculture and Resilient Systems, American Olive Oil Producers Association (AOOPA), and the California Olive Ranch, as part of the California Department of Food and Agriculture’s (CDFA) Pollinator Habitat Program grant to advance pollinator-friendly practices.
Participants will gain practical knowledge on pollinator habitat establishment, biological pest control, regenerative practices in olive groves, and the latest research on olive knot management.
This event also offers continuing education opportunities, including 3 hours of American Society of Agronomy (ASA) CEUs (approved) and 1 hour of California Department of Pesticide Regulation (DPR) CEUs (requested).
Availability is limited—click the link below or scan the QR code on the flyer to register today: Register Here
Membership Opportunities
AOOPA advocates for fair trade rules and market access, supports industry growth and promotes quality standards all consumers can trust. As we continue to work on behalf of the American olive oil producers and consumers, we ask that you support our efforts by maintaining your membership and sharing membership opportunities with other industry leaders and affiliate businesses
For a list of membership opportunities please visit our us at aoopa.org or contact us at info@aoopa.org with any questions you may have about AOOPA. All applications are subject to approval by the Board of Directors. Memberships are paid on an annual basis.
Huanglongbing (HLB), the deadly citrus disease that decimated the Florida citrus industry has shown up in Southern California and is now threatening the nation’s number one citrus state. HLB is primarily spread by the invasive Asian Citrus Psyllid, so managing this insect is key to preventing the spread of the disease. Pest mitigation practices may be costly, the California Citrus Research Board (CRB) introduced the California Citrus Research and Field Trials program (CA-CRaFT) to help fund commercial growers (both conventional and organic) to implement these practices. CRB representative Ivan Milosavljevic met with Matthew Malcolm on California Ag Network to share details. Watch this brief interview and read more in California Fruit & Vegetable Magazine.
Mark Bolda, coastal UCCE Strawberry and Caneberry Farm Advisor, was easing into some Sunday morning reading recently at a small park in Watsonville that is very close to a strawberry field when the unusual insect depicted below paid him a visit. Given that he had never seen this insect (and doubts that many of you have either), he felt a surge of unease that this could be a new one, in other words an invasive.
A quick check to Dylan Beale, our new UCCE Entomologist serving all three counties of the Central Coast, put all of this to rest. After some research into the identification, Dylan determined that this very likely Megaloceroea recticornis, of the insect family Miridae. The species originated in Eurasia and North Africa but has become established in North America and New Zealand. Nymphs and adults prefer to feed on grasses, which makes a lot of sense since this is exactly the environment it was found.
All is well then, and we can continue on to other things.
Fusarium wilt of lettuce, caused by Fusarium oxysporum f. sp. lactucae (FOL), is an economically significant disease on the Central Coast of California. We conducted field trials to evaluate 30 iceberg and 21 romaine varieties for tolerance to Fusarium wilt. The trials were located in commercial fields in Greenfield, CA (wet date of May 27, 2024) and Salinas, CA (wet date of June 8, 2024). Foliar disease severity was visually evaluated on July 31-August 2, 2024 at Greenfield and on August 5-7, 2024 at Salinas and converted to a marketability (yes or no) rating. Disease pressure was high at both locations. Iceberg varieties that exceeded 50% marketability at both locations were Powerball and two coded entries from Vilmorin-Mikado. Nine varieties exceeded 50% marketability at Greenfield but not Salinas, and two varieties exceeded the same threshold at Salinas but not Greenfield. For romaine, 19 out of 22 varieties exceeded 90% marketability at Greenfield, but only two of those varieties (Holbrook and Momentus) also exceeded the same threshold at Salinas. In a greenhouse experiment, isolates from Greenfield showed a susceptible reaction on variety Costa Rica #4, which is consistent with the Costa Rica FOL race variant. Although FOL race 1 is suspected to be present at the Salinas location, greenhouse testing is not complete. These trials provide public data on the tolerance of iceberg and romaine varieties to Fusarium wilt.
Methods
Field trials were conducted in Greenfield, CA and Salinas, CA to evaluate both in-slot and out-of-slot varieties (30 iceberg and 21 romaine) for tolerance to Fusarium wilt in commercial fields with disease history. At Greenfield, bed center spacing was 80 inches, and plots were 1 plant line wide by 100 ft. long. Due to space constraints, 4 iceberg and 10 romaine varieties were not included in the Salinas trial. At Salinas, bed center spacing was 40 inches, and plots were 1 plant lines wide by 40 ft. long. Iceberg and romaine varieties were evaluated separately, and plots of each type were arranged in a randomized complete block with four replications. Treatments were direct seeded using the grower-cooperators’ planters at Greenfield and using single-line push planters at Salinas. The wet dates were May 27, 2024 for Greenfield and June 8, 2024 for Salinas. The Greenfield trial was maintained to commercial standards for lettuce production, whereas the Salinas trial was not. After thinning by commercial crews, 50 plants at Greenfield and 30 plants at Salinas in the center of each plot were counted, and the section was marked with stakes. Data were collected from this center section. Evaluations were performed on July 31-August 2 at Greenfield and August 5-7 at Salinas, which was before maturity at the Salinas trial. Foliar disease severity was assessed on a 0 to 4 scale where: 0 = healthy; 1 = wilting or chlorosis of one to three outer leaves; 2 = up to moderate stunting and wilting or chlorosis of <25% of leaf area; 3 = head is severely stunted or absent and between 25% and 75% of leaf area is wilting or chlorotic; and 4 = head is absent and >75% of leaf area is chlorotic and nearly dead, or plant is entirely dead. For analysis, foliar disease severity was converted to marketability, where: disease severity of 0 or 1 = marketable; and disease severity of 2, 3, or 4 = not marketable. Marketability data was analyzed by an analysis of variance (P < 0.05), and variety means were separated using Tukey’s honestly significant difference test.
Results – Race of the FOL pathogen present
Two races of FOL are present on the Central Coast: race 1, and a novel race variant (Nayak et al., 2024). We are using the temporary name “Costa Rica FOL variant” for the novel race variant until it is officially named following completion of the upcoming ring test, which is a collaborative experiment between researchers and seed companies. To determine the FOL race present, isolates from each location were evaluated in a race typing experiment in the greenhouse. Variety Costa Rica #4 showed a susceptible reaction to both Greenfield isolates, which supports the observation that the Costa Rica FOL race variant is present at the Greenfield location. We suspect FOL race 1 is present at the Salinas location. However, greenhouse testing of the Salinas location isolates is ongoing.
Results – Marketability
Disease pressure was high at both locations. Iceberg varieties that exceeded 50% marketability at both locations were Powerball and two coded entries from Vilmorin-Mikado (Table 1). Nine varieties exceeded 50% marketability at Greenfield only: Balboa, Fontinas, Meridian, Paraiso, San Andreas, San Miguel, two coded entries from Salinas Valley Seeds, and one coded entry from Sakata. In contrast, two varieties exceeded the same threshold at Salinas only: Fredonia and a coded entry from Takii. This pattern of some varieties showing large differences in performance between locations whereas others showed similar performance suggests that a different race is present at each location, but this has not yet been confirmed by greenhouse testing.
Of the 21 romaine varieties evaluated, two varieties exceeded 90% marketability at both locations: Holbrook and Momentus (Table 2). A total of 17 out of 21 varieties exceeded the same threshold at Greenfield but not Salinas. At the Salinas location, Holbrook and Momentus were not statistically different from four varieties (Boronda, Copious, Patton, and Solid Heart) with average percent marketability ranging from 77% to 88%.
If you have additional questions about these trials, please contact Alex Putman at 951-522-9556 or aiputman@ucr.edu.
Please Send Us Samples
We are continuing to collect samples of lettuce Fusarium wilt to determine the distribution of races and to monitor the pathogen. To support this research, please contact the person in your region. Your help would be greatly appreciated.
Monterey, San Benito, or Santa Cruz Counties – Yu-Chen Wang (831-201-9689 or yckwang@ucanr.edu)
San Luis Obispo, Santa Barbara, or Ventura Counties – Chris Greer (805-888-1355 or cagreer@ucanr.edu)
Any other California county – Alex Putman (951-522-9556 or aiputman@ucr.edu)
Acknowledgements
We are grateful to D’Arrigo Brothers Co. of California and an anonymous grower for the space and maintenance of the variety field trials. We thank seed producers for providing seed for the trial. Funding for this project was made possible by a grant from the U.S. Department of Agriculture (USDA) Agricultural Marketing Service. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the USDA. Funding was also provided by the California Leafy Greens Research Program.
References
Nayak, S., K.L. Richardson, A.I. Putman, N.R. LeBlanc, F.N. Martin, N. Li, and J.D. McCreight. 2024. Detection of novel pathogenic variants of Fusarium oxysporum f. sp. lactucae in California. Plant Pathology Early View. doi:10.1111/ppa.14019
Since the mid-2000s, citrus greening disease or Huanglongbing (HLB), has taken a toll on citrus fruits, causing significant crop and economic losses for citrus growers from Florida to Texas, and threatening to make its way to California — the nation’s #1 citrus state.
An aerial view of the new APHIS-funded Grove-First test site. Here researchers can partner with ARS scientists to evaluate therapies to combat citrus greening disease. (Photo by Cody Estes, owner of Estes Citrus Inc., Vero Beach, FL).
Photo Caption: An aerial view of the new APHIS-funded Grove-First test site. Here researchers can partner with ARS scientists to evaluate therapies to combat citrus greening disease. (Photo by Cody Estes, owner of Estes Citrus Inc., Vero Beach, FL).
With citrus trees in all major U.S. citrus-producing states affected by the bacterial pathogen, the Agricultural Research Service (ARS) is working to combat the disease. Citrus greening affects a variety of citrus fruits — with the greatest damage occurring within Florida’s orange groves.
Through the project “Grove-First,” ARS scientists Michelle Heck and Randall Niedz are working to stop citrus greening from overtaking these vital crops. Grove-First invites fellow researchers, citrus growers, and industry experts to test their scientific models to curb the effects of citrus greening directly in the field.
“We want to provide access to anyone in the research community to test their therapy against citrus greening,” said Heck. “This new project is going to open the door [to further research] and obliterate the barrier between the lab and the field. We are going to provide researchers with the ability to test their therapies directly in the field.”
With the support of ARS and USDA’s Animal and Plant Health Inspection Service (APHIS), Grove-First will leverage a commercial grove in Vero Beach, FL, to evaluate different treatments on both mature and young trees.
“The only way to determine if a treatment works is to actually see it work in the field,” added Niedz. “When you have a woody perennial like citrus trees, they are large, and therefore expensive to grow. Most researchers simply don’t have the resources, or access to the trees. With Grove-First, we now have a field site to welcome collaborations with some of the best researchers in the country.”
Heck tributes citrus growers for bringing Grove-First to fruition as a collaborative project. She said that in the past, the only way growers could fight citrus greening disease was to deliver therapies to trees using broadcast sprayers or through irrigation lines.
Because citrus greening disease attacks the vascular tissue of citrus trees, many growers have now turned to injecting individual citrus trees with an antibiotic treatment, such as oxytetracycline, which delivers more immediate treatment.
“The innovation to open up field testing and Grove-First research came from grower willingness to treat each individual citrus tree by direct injection,” said Heck. “This was transformative.”
Grove-First will welcome researchers with three important considerations.
“We want the treatments to be safe … safe for the (citrus) trees and safe for the workers,” Heck said. “They also must be affordable for the grower, and they must be available. The treatments that are safe, affordable, and available will be prioritized for screening through Grove-First.” – By Tami Terella-Faram, USDA-ARS Office of Communications
It doesn’t require a degree in ornithology, a lab test or even an app for most growers to determine whether bird poop near their crops presents a food safety risk. They just need to ask themselves a simple question: How big is it?
That’s according to a study from the University of California, Davis, published today in the Journal of Applied Ecology. The study said an informed, nuanced view of food-safety risks and wild birds could help growers avoid crop losses and manage farms for food safety, biodiversity conservation and crop production.
Since 2006, when an E. coli outbreak devastated the U.S. leafy greens industry, growers have been pressured to remove natural habitat to keep wildlife — and the foodborne pathogens they sometimes carry — from visiting crops. Growers are often advised not to harvest crops within a roughly three-foot radius of any wildlife feces, lest they risk failing a food safety audit or losing a buyer contract. Growers often cite such concerns as a barrier to implementing conservation actions they would otherwise consider taking on their farms.
“We wanted to find out the true risk of wild birds to food safety,” said lead author Austin Spence, a postdoctoral researcher in the UC Davis Department of Wildlife, Fish and Conservation Biology. “Which birds have pathogens, which birds are spending time on farms, and if a bird has a pathogen, does that pathogen survive long in bird poop? Our findings indicate that we can co-manage our areas for both agriculture and conservation.”
Northern harrier on sprinkler in leafy-green field, coastal CA (image by Rose Albert, UC Davis)
Where pathogens persist
Through field and greenhouse experiments, bird surveys, point counts and fecal transects, the authors assessed food-safety risks from nearly 10,000 birds across 29 lettuce farms on California’s Central Coast. They spent hours following turkeys, bluebirds and other wild birds at the UC Davis Student Farm and nearby Putah Creek, collecting hundreds of fecal samples. They compared E. coli survival in bird droppings on lettuce, soil and plastic mulch to measure pathogen persistence.
After all of these efforts, they landed on a simple finding: Smaller poops from smaller birds carry very low risk of foodborne pathogens, which were rare in birds overall. If a bird were to become infected, pathogen survival depends heavily on the bird’s size.
“Birds that are large produce really big feces, and that’s where pathogens are more likely to survive,” said Spence. “Birds that are small have tiny feces, and the pathogens die off quickly. So farmers don’t have to know the species of bird it came from. They just need to know the size. If it’s the size of a quarter, don’t harvest near that. If it’s a tiny white speck, it’s very low risk and probably fine.”
Loggerhead shrike in a cabbage field with farmworker in background (Image by Rose Albert, UC Davis)
Balancing conservation, crop yields, and food safety
Beyond fecal size, what the birds pooped on — be it the crop, soil or plastic — made a difference for pathogen survival. In the study, E. coli survived longer on lettuce itself than on soil or plastic mulch.
Fortunately, about 90% of birds observed on the farms were small and tended to poop mostly on soil, where pathogens perish quickly. By avoiding no-harvest buffers when food-safety risks are low, growers of leafy greens could harvest about 10% more of their fields.
“Birds generally present really low food-safety risks,” said senior author Daniel Karp, a UC Davis professor in the Department of Wildlife, Fish, and Conservation Biology. “The industry has been concerned about birds for a while. But pathogenic E. coli and Salmonella are vanishingly rare in wild, farmland birds. And we now know E. coli tends to die off quickly in most bird poop.”
The study opens up new strategies for growers to better balance conservation and food-safety risks. For example, growers could erect nest boxes to attract small, beneficial insect-eating birds, like bluebirds and swallows, that help control pests without risking food safety.
The work also contributes to a growing body of research that suggests growers do not need to remove habitat to improve food safety.
“There have been no studies to date that suggest habitat removal improves food safety,” Karp said. “Habitat around farms is actually likely to favor the small, insect-eating birds that are unlikely to carry pathogens. Studies like ours are giving farmers science-based permission to conserve habitat — and many species of wild birds — on their farms again.”
The study’s additional co-authors are Jeffery McGarvey and SangIn Lee at the USDA Agricultural Research Service, Olivia Smith at Michigan State University, Elissa Olimpi at Conservation Science Partners, and undergraduates Wentao Yang and Meirun Zhang at UC Davis.
The study was funded through the Center for Produce Safety, the California Department of Food and Agriculture and the U.S. Department of Agriculture. — By Kat Kerlin, UC Davis
California Avocado Commission — The California Department of Pesticide Regulation has issued a section 24(c) Special Local Needs registration for Forfeit® 280 (glufosinate-ammonium) herbicide for use in avocado groves. This registration is effective through October 31, 2029. Growers wishing to use Forfeit® must have a copy of the SLN label in their possession during use. The label can be found on the California Avocado Commission website.
As you may recall, in May 2024 we alerted the industry that the California Department of Pesticide Regulation (DPR) had finally approved the herbicide Rely® 280 (glufosinate-ammonium) for use in avocado groves in California. The process to get Rely® registered had taken about five years and was a much-needed tool for California avocado growers to manage glyphosate (Roundup®) resistant weeds.
Unfortunately, in late August we received word that BASF, the manufacturer of Rely®, had “chosen to discontinue production of Rely Herbicide.” This was shocking information to receive given the time that had been invested in obtaining this registration. And as we learned, it was a decision that was just as surprising to our contacts at BASF who had worked closely with us on the registration process.
The California Avocado Commission is grateful to Loveland Products for their willingness to support our application for an SLN registration for Forfeit®. We also are grateful to DPR for the rapid review and approval of our application. We know that glufosinate-ammonium is an important tool for growers and we are happy that this disruption was relatively minor and growers will have Forfeit® available to them for the spring weed management season.
As a reminder, Rely® (the BASF product) is still registered for use on avocados and is legal for use as long as supplies last, but growers must have a copy of the DPR approved label that has a stamp on it with the wording “LABELING ACCEPTABLE State of California Department of Pesticide Regulation Pesticide Registration” and can be found on the CAC grower website here: (https://www.californiaavocadogrowers.com/sites/default/files/Rely-280-NVA-2022-04-0598-0238-avocado.pdf).
CDFA is announcing four vacancies on the Citrus Pest and Disease Prevention Committee. The Committee advises the CDFA secretary on activities associated with the statewide citrus pest and disease work plan that includes outreach and education programs and programs for surveying, detecting, analyzing, and treating pests and diseases specific to citrus.
The Committee member vacancies are for two grower representatives in Fresno County (one term expiring September 30, 2027 and the other term expiring September 30, 2028); one grower representative in Tulare County with a term expiring September 30, 2028; and one nursery representative with a term expiring September 30, 2027. Applicants should have an interest in agriculture and citrus pest and disease prevention.
Members receive no compensation but are entitled to necessary travel expenses in accordance with the rules of the California Department of Human Resources.
Individuals interested in a committee appointment should submit a resume/CV by January 1, 2025 to the California Department of Food and Agriculture, Citrus Pest and Disease Prevention Division, 1220 N Street, Sacramento, CA 95814, Attention: David Gutierrez.
For more information contact: David Gutierrez, Interim Director, Citrus Pest and Disease Prevention Division at 916-274-6300 or email (David.Gutierrez@cdfa.ca.gov).
The California Association of Pest Control Advisers (CAPCA) recently gathered for their 50th annual conference. Bringing together a bright group pest control advisors tasked with protecting the most diverse agricultural landscape in the nation, watch this special video presentation highlighting what CAPCA is all about and what it means to be a member of this organization as they celebrate this milestone year.
California’s prune industry faces a significant challenge: a decline in orchard lifespan. Average productive life has shrunk from an estimated 30 years in 1998 to just 20 years as of 2022 (UC Cost and Return Studies). Heat stress, repeated mechanical damage, and disease are likely contributing factors. A primary disease culprit associated with premature orchard decline is the loss of fruit-producing scaffolds likely caused by the heart rot fungus Phellinus pomaceus (formerly called P. tuberculosus).
Phellinus pomaceus specifically targets Prunus spp., unlike most wood decay fungi which have a broader host range. This fungus is common in natural forests of Europe and Asia. It invades the heartwood, causing white rot that weakens branches. In California prune trees, this results in broken branches that reduce fruit production. Additionally, weakened trees become more susceptible to other stressors, ultimately shortening orchard lifespan.
Prune growers should be aware of the signs of Phellinus pomaceus infection. Look for shelf-like fruiting bodies (conks) on trunks or branches (see photos) – these are the fungus’ reproductive structures and indicate established infection. Additionally, broken or pruned branches with exposed white rot decay (also pictured) can indicate the disease. Growers often discover this internal heart rot in major scaffolds leading up to and during harvest, when branches that appear healthy snap under the weight of fruit or during shaking– aka “blowing up.”
Our research in investigating Phellinus pomaceus and developing management strategies is supported by funding from the California Prune Board. We are focused on investigating several key areas:
Distribution of the fungus, its impacts, and management choices: We are surveying prune orchards to assess the prevalence and severity of infection statewide and investigating potential links between disease occurrence and factors like pruning practices, irrigation types, spray applications of dormant oils, the presence of other pathogens, and local weather conditions. Surveys in mature prune orchards reveal a high prevalence of Phellinus pomaceus infection levels in the Sacramento Valley compared to historical studies, with all surveyed contemporary orchards over 14 years showing signs of the infection. Conversely, extremely limited infection has been observed so far in the San Joaquin Valley. Weather stations have been installed in 10 orchards from Red Bluff to Madera since Fall 2023 and provide specific in-orchard conditions that may be related to the progression of the disease.
Additionally, we are collaborating with researchers in France and South America to see if Phellinus pomaceus is a problem in other major prune-producing regions. Surveys in Chilean prune orchards are planned for September 2024 with additional funding from UC Davis Chile Life Sciences Institute.
Potential Control Methods: Since there is currently no known chemical control for Phellinus pomaceus, we are exploring bio-control alternatives. Two trials are underway to investigate the potential of Trichoderma spp. (a beneficial fungus used as a bio-control product in other crops, one trade name is Vintec®), to protect pruning wounds from Phellinus pomaceusinfection. The first trial is a multi-year project (started in 2020) wherein orchard blocks have been sprayed with Trichodermaproducts annually and disease progress is being monitored. Due to the slow progression of this disease, results will not be clear for many more years. The second trial is direct application on fruiting bodies to observe any effects on growth and spore production. After a single season in this trial, unfortunately Phellinus appears unhampered in its life cycle – though these results are still pending. A third trial is upcoming and will consist of targeted pre-inoculation of fresh pruning wounds with different combinations of Phellinus pomaceus spores and Trichoderma bio-controls and re-sampling a short time later to observe disease progression in the presence of these alternative spray applications.
Spore Dispersal and infection routes: Understanding the life cycle of fungal pathogens is crucial for disease prevention, though current literature is lacking in relevant studies on Phellinus pomaceus. We are working to understand how the disease colonizes and spreads in California prune orchards. Recent dissection of infected trees indicates the primary route of infection is through pruning wounds, which are colonized by airborne spores released by the fungus during specific windows.
We are monitoring airborne fungal spores in orchards throughout the year to identify these peak periods of Phellinus pomaceusspore dispersal. This information can help growers time pruning activities to minimize infection risk. Initial results show peak spore production in late January to early April, depending on the region. These data currently support orchard managers to avoid pruning during this time, when chances of infection are likely highest. More official data will be coming in the next year.
Fruiting body of Phellinus pomaceus. Characteristic association with pruning wounds shown in A, B, D, E. Scale bars 10 cm (4 inches).
We will continue to share our findings and develop management recommendations for growers. Stay tuned for future updates on the completion of orchard surveys and the impacts of orchard management practices, the results of Trichoderma spp. trials, and how our growing understanding of the life cycle of Phellinus can improve management of the disease. We are grateful to the California Prune Board for generously funding this important research.
Please reach out to Laurel Hoffman, PhD Graduate Student in the lab of Dr. David Rizzo of the UC Davis Dept. of Plant Pathology if you have concerns or questions about this research at Hoffman@ucdavis.edu. — ByLaurel Hoffman, UC Davis Dept. of Plant Pathology PhD Graduate Student, Rizzo Lab
