California Fruit and Vegetable

Category: Non-Video

  • California Citrus Grower’s Conference, Oct. 23

    Growers are invited to register now for the Citrus Research Board (CRB)’s Annual California Citrus Grower’s Conference on October 23, 2024, in Visalia, California, at the Visalia Convention Center. Registration will close on Monday, October 14.

    This event is designed specifically for growers and will showcase the outstanding research efforts ongoing for the benefit of California citrus growers and industry. This conference is an invaluable opportunity to learn, connect with fellow growers, and stay involved with innovative research. Additional information can be found at the registration link HERE.

    Scheduled Speakers

      • Casey Creamer, California Citrus Mutual
      • Ashraf El-kereamy, Ph.D., University of California, Riverside
      • Ivan Milosavljević, Ph.D., Citrus Research Board
      • Sandipa Gautam, Ph.D., University of California Agriculture and Natural Resources
      • Daniele Zaccaria, Ph.D., University of California, Davis
      • Raymond Yokomi, Ph.D., USDA Agricultural Research Service
      • Isaac Mazor, Nanovel LTD
      • Amanda Zito, Fresno County Department of Agriculture
      • Luxin Wang, Ph.D., University of California, Davis
      • James (Jim) Adaskaveg, Ph.D., University of California, Riverside
      • Melinda Klein, Ph.D, Citrus Research Board
      • Bodil Cass, Ph.D., University of California Agriculture and Natural Resources
      • Robert Clark, Ph.D., EcoData Technology

    Continuing Education Units (CEUs)

    The following continuing education units have been approved:
    • Department of Pesticide Regulations – 1.5 hours of Other and .5 hours of Laws & Regulations
    • Certified Crop Advisers – 2.5 hours of Integrated Pest Management, .5 hours of Soil & Water Management, and .5 hours of Crop Management

  • What Are You Doing For Your Orchard’s Financial Longevity?

    Your prune orchard is an investment – the longer it remains a productive, high-yielding orchard the higher your return on that investment and the longer you can avoid the (very expensive) need for orchard removal, replanting, and years of non-bearing and low initial yields.

    Do you know what thiophanate-methyl is? It is the active ingredient in the fungicide Topsin-M. While this is not a pesticide advertisement or recommendation, research from the lab of Dr. Themis Michailides (UC Davis, based at Kearney Ag Research & Extension Center) has shown that Topsin-M is the most consistently effective fungicide for protecting fresh pruning wounds. Pruning wounds are very easily colonized by canker causing fungi (Cytospora, Botryosphaeria, and others). These fungi infect the fresh pruning cut with wind splashed spores during rainstorms.

    So, all you must do is prune, quickly clear the brush, and apply Topsin-M or another thiophanate-methyl product? Unfortunately, it’s not quite that simple. Although this fungicide is the best protective spray we have to-date, it significantly reduces but does not prevent all canker infections that can shorten your orchard’s lifespan. Still, to give your orchard the best shot at long sustained health and financial viability -integrate this spray in with other best practices:

    1. Skip pruning when you can (following a heavy crop, the year after detailed pruning, etc.), but make sure to shaker thin if a heavy crop sets because limb breakage is also an opportunity for canker infection.
    2. Prune around rain whenever possible. Early fall or after bloom are pruning timing options that may (should?) avoid rain. Never prune with rain in the forecast.
    3. Quickly push brush and consider spraying with a thiophanate-methyl product (Topsin®-M, etc.).
    4. Prune out and remove dead wood in the orchard to reduce canker inoculum. Burn pruning debris where permitted.

    *Note, Mention of any chemistries or trade names does not constitute a recommendation and are for informational purposes only. Always consult with your PCA before use and adhere to the pesticide label and local and state regulations.  — By Luke Milliron, UCCE Orchard Advisor Butte, Glenn & Tehama Counties, and Franz Niederholzer, UCCE Farm Advisor, Colusa, Sutter & Yuba Counties

  • Phellinus Wood Rot, or “Why do my Prune Trees Blow up at Harvest?”

    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. — By Laurel Hoffman, UC Davis Dept. of Plant Pathology PhD Graduate Student, Rizzo Lab

  • Avocado Sales Back to Record-Breaking Highs

    Second quarter holidays generated the highest growth rates in 2024 according to the most recent Avocado Holiday Retail Recap created by the Hass Avocado Board (HAB). Cinco De Mayo, Memorial Day and Father’s Day sold a combined 154.6 million units, generating $191.6 million in dollar sales, a $32.4 million increase in dollar sales versus 2023.

    Additionally, all three holidays contributed to category promotional gains in promotional lift. During Cinco de Mayo week, small avocados (4046) fueled unit growth due to their large share of category sales. However, promotional performance showed large avocado (4225) promotions outperformed small avocados (4046) and bagged avocados, driving a +73.2% promotional lift in volume, +35.7 points higher than the promotional volume lift achieved by small avocado (4046) promotions.

    Key highlights from the report include:

    • Cinco De Mayo sales and units soared, reaching four-year highs in both dollars and units. Avocado units reached 59.8M, a +2% increase versus the prior year, while dollar sales soared +22% to $68.5M. Small avocados (4046) drove unit growth during the holiday, contributing an additional +3.1M units to the category.
    • During Memorial Day, avocado dollars climbed +18% to $61.5M in sales while units fell -2% to 47.5M units. The average holiday selling price reached $1.29/unit, a +20% increase compared to the prior year.
    • Father’s Day avocado dollar sales secured $61.6 in sales, a four-year high and a +22% increase from the prior year while unit sales declined -1% to 47.3M units. Large avocados promotions performed well during the holiday generating the highest promotional volume lift at +20%.
    The Hass Avocado Board’s recently published second quarter retail recap notes that Cinco De Mayo promotions for large avocados (4225) outperformed other Q2 holidays. Promoted sales of large avocados generated a volume lift for each holiday. However, Cinco De Mayo largely outperformed other summer holidays.

    The Avocado Holiday Retail Recap provides detailed analyses of promoted and non-promoted volume and dollar sales, pricing dynamics, lift metrics, and promotional efficiency across various bulk avocado sizes and bagged avocados. Each report also details regional sales information providing insightful information for future holiday promotion planning.

    For a complete overview of avocado sales performance during each 2024 holiday please visit hassavocadoboard.com and download the full report.

    About The Hass Avocado Board

    The Hass Avocado Board (HAB) exists to help make avocados America’s most popular fruit. HAB is the only avocado organization that equips the entire global industry for success by collecting, focusing, and distributing investments to maintain and expand demand for avocados in the United States. HAB provides the industry with consolidated supply and market data, conducts nutrition research, educates health professionals, and brings people together from all corners of the industry to collectively work towards growth that benefits everyone. The organization also collects and reallocates funds to California and importer associations to benefit specific countries of origin in promoting their avocado brands to customers and consumers across the United States.

  • UC Davis Researchers Target Spotted-Wing Drosophila and its Threat Against California Berries

    Back in 2010, the UC Davis entomology labs of integrated pest management specialist Frank Zalom and molecular geneticist and physiologist Joanna Chiu  joined forces to target the spotted-wing drosophila (SWD), a serious threat to berry production in California.

    Drosophila suzukii, native to southeast Asia and first discovered in California in 2008, lays its eggs in such soft-skinned, ripening fruits as strawberries, raspberries, cherries, blueberries, peaches, nectarines, apricot and grape.

    It packs a powerful economic impact. The first year of its discovery in California, the economic loss amounted to $500 million. Latest statistics from 2015 indicate a $700 million national economic loss.

    The Zalom lab discovered the first SWD field populations with insecticide resistance in 2017. As the pest continues to spread throughout much of the country, anxious growers are worried about its increased resistance to pesticides.

    The team’s newly published research in Scientific Reports is the first to characterize the molecular mechanisms of insecticide resistance in D. suzukii and provide insights into how current management practices can be optimized.

    Lead author of the paper, “Transcriptome Analysis of Drosophila suzukii Reveals Molecular Mechanisms Conferring Pyrethroid and Spinosad Resistance,” is Christine Tabuloc, then a doctoral candidate and now a postdoctoral researcher working under the mentorship of Professors Chiu and Zalom.

    “In this work, we leveraged high throughput sequencing to identify biomarkers of insecticide resistance in D. suzukii,” Tabuloc explained. “We found that different genes are responsible for resistance to different chemicals. Specifically, we found that genes involved in metabolism are highly expressed in flies resistant to pyrethroid insecticides. We also observed evidence of two different mechanisms of resistance in 2 lines generated from a single spinosad-resistant population. We found an increased expression of metabolic genes in one line and increased expression of cuticular genes in the other.”

    “Therefore, we developed a diagnostic panel using these biomarker genes to differentiate between pyrethroid resistance and spinosad resistance,” Tabuloc related. “Not only can our assay now inform whether there is resistance, it can tell us which chemical the population is resistant to and how severe the resistance is. Additionally, this method is faster, enables for the testing of more populations, and is more comprehensive as compared to bioassays, the conventional way of testing for resistance.”

    Tabuloc added that “our work has enabled for the detection of resistance in California populations, and we are currently doing a nationwide screening to determine whether resistance is now present in other states. Currently, we are working with the Zalom lab to use the results of our assays to try and combat resistance. There are experiments in progress trying to increase the efficacy of insecticides by blocking some of the genes involved in resistance, such that the enzymes encoded by those genes have decreased function.”

    Zalom, a UC Davis distinguished professor emeritus who directed the UC Statewide Integrated Pest Management Program for 16 years, said he has been “working on spotted-wing drosophila with Dr. Chiu and her lab members since she joined the UC Davis faculty in 2010, and it has been an absolute pleasure.”

    Zalom, a past president of the 7000-member Entomological Society of America (ESA) and an elected Honorary Member, ESA’s highest honor, praised Chiu, a 2019-2024 Chancellor’s Fellow professor and now chair of the Department of Entomology and Nematology, as “one of the most collaborative researchers who I have ever worked with. When our lab found the first SWD field populations with insecticide resistance in 2017, it seemed obvious to ask Dr. Chiu about identifying the mechanism of resistance to different chemical classes and if it would be possible to develop a molecular diagnostic to confirm presence of  insecticide resistance in field populations without conducting the time consuming and labor-intensive bioassays that we were using.”

    “Dr. Chiu and her PhD student Christine Tabuloc took on this challenge and their work culminated in the description of genes associated with the resistance and the diagnostic assay presented in this paper,” Zalom said.

    The Zalom lab “selected the SWD isolines from California field populations displaying resistance to pyrethroids and spinosyns after conducting bioassays on many hundreds of SWD adults, then helped Dr. Tabuloc validate  results of the molecular assay,” he said.

    “This work not only represents good science; it has very practical implications,” Zalom said. “Dr. Tabuloc and I presented results of the work from both of our labs at a special berry grower seminar on insecticide resistance organized by UC Agriculture and Natural Resources (UC ANR) Farm Advisor Mark Bolda in Watsonville. The presentations were extremely well-received. The original program was targeted for about 1.5 hours, but the meeting extended to over three hours due to the extent of questions and great discussion that followed. Growers and their consultants are hungry for new information that they find interesting and potentially useful, and this work was clearly of interest to them.”

    Bolda, strawberry and caneberry farm advisor in Santa Cruz, Monterey and San Benito counties, “was the first person who found the insect and asked me to come down to look at it and the problem,” Zalom remembered. “That was 2008, and we weren’t able to get an actual species identification until 2009!”

    Bolda noted that the recent berry grower meeting targeted SWD resistance on the Central Coast, with the UC Davis entomologists presenting. “The research was top shelf and the need, of course, is very great,” Bolda said. “Some of the information that Frank and Christine presented has been put into immediate use in the industry.”

    “What made it really special was that since we were moving only a month or so later, and this was the last Extension meeting to be held at my UC Cooperative Extension Office,” Bolda said. “After 40 some years, that’s saying a lot and it was totally apropros that Frank, given his many, many years of service, was the very last to run a meeting there….and Christine presented also…she was really great and presented fabulous information.”

    Among the “iconic individuals of Central Coast strawberries” who attended, Bolda said, was retired entomologist Ed Show (Driscoll Strawberry Association, Inc.) “who has been a part of strawberries since the 1970s.”

    “It was nostalgic for me since it was the last meeting that was held there because they were moving to a new office,” Zalom said. “I must have done 80 presentations at that auditorium over the years, including some of the very first ones that I did when returning to California when I was doing research on brussels sprouts and apples in that area.”

    Fruitville Collaboration. Professor Chiu said the publication “culminated years of fruitful collaboration and hard work by our lab and Professor Zalom’s lab, primarily driven by Christine…This research could not have been accomplished without Christine who is uniquely qualified to successfully lead the project; she combines her knowledge in insect genomics and bioinformatics with Drosophila molecular genetics.”

    Chiu pointed out that “When the Zalom lab and my lab first started our collaboration in 2010, we were already worried about the potential development of insecticide resistance in D. suzukii given the primary method for management is insecticide application and the generation time of these flies are short. Unfortunately, this became a reality in 2017.”

    “We hope that our research in developing more efficient molecular diagnostics to identify resistant populations will help prevent the spread of resistance to other U.S. states by allowing them to be proactive; perhaps to adjust their management program as soon as low level of resistance is detected,” Chiu said. “We are continuing to perform research to determine if resistance, once found, can be ‘weakened’ and what are mechanisms that could drive it. We think this will be very beneficial for growers in California, who currently have to tackle D. suzukiiwith insecticide resistance.”

    Tabuloc, who joined the Chiu lab as an undergraduate research assistant in 2012, received her bachelor of science degree in biochemistry and molecular biology from UC Davis in 2015, and her doctorate from UC Davis in 2023.

    In addition to Chiu, Zalom and Tabuloc, the 12-member team of researchers and co-authors included Curtis Carlson, Kyle Lewald, Sergio Hidalgo, Cindy Truong and Ching-Hsuan Chen, all from the Chiu lab; Nicole Nicola and Fatemeh Ganjisaffar of the Zalom lab; and Cera Jones and Ashfaq Sial of the Department of Entomology, University of Georgia, Athens. At the time, Truong and Chen were undergraduates, and Ganjisaffar was a postdoctoral fellow, and now a senior environmental scientist with the California Department of Food and Agriculture.

    Federal and state grants awarded to Chiu and Zalom funded the project: a USDA National Institute of Food and Agriculture; and a California Department of Food and Agriculture Specialty Crop Block Grant. The team credits Bloomington Drosophila Stock Center for providing D. melanogaster stocks.

  • Ag Community Mourns Loss of Tim Gerdts

    The sudden passing of Tim Gerdts on August 26, 2024, marked a day of mourning for both the company he dedicated 38 years to and the fruit and nut community he supported.  Tim began his tenure at Burchell Nursery as a sales representative in 1986, after serving as a field supervisor and lead at Gerawan Farming. At the time, Burchell Nursery was expanding with a new branch in Fowler, CA, and required a sales representative for the Fresno area.  Residing in Kingsburg, a Fresno State alumnus, Tim was well-acquainted with the local growers and fruit packers.

    Raised in an agricultural environment, with his father serving as a UC Cooperative Extension Farm Advisor, Tim learned orchard management firsthand.  At Burchell Nursery, he leveraged this knowledge to offer growers guidance on pruning, planting, rootstock selection, and varietal recommendations.  Tim was often seen in peach or almond orchards, demonstrating proper pruning techniques to growers.

    Tim played a pivotal role in the Burchell Nursery Breeding Program, contributing to the introduction of over 70 peach and nectarine varieties, many of which, like the Autumn Flame peach, have become industry benchmarks.  He also collaborated with Bradford Farms to launch numerous new stone fruit varieties from their breeding program.  Tim’s relentless search for the ideal variety, whether new of established, always aimed to advance the grower’s success.

    Beyond his exemplary sales representation, Tim was a cornerstone during the winter delivery season, assisting in the distribution of trees.  He managed the Burchell Nursery Fowler sales yard, overseeing the coordination of tree shipments and deliveries to clients.  Working in tandem with truck drivers and office staff, he ensured seamless deliveries to meet customer readiness.  Tim’s commitment extended to operating a forklift for loading trucks or being present at a customer’s orchard early in the morning.

    His untimely passing is a loss that will resonate throughout the agricultural industry, as we have lost one of the most knowledgeable tree experts.  His presence will be profoundly missed by everyone that knew him.

    In lieu of flowers, the Gerdts family has asked that donations be made to the Fresno Rescue Mission.

  • UCCE Carrot Production and Pest Management Webinar, Oct. 9

    As part of the UC Ag Experts Talk webinar series, Dr. Jaspreet K. Sidhu, Vegetable Crops Farm Advisor with the University of California Cooperative Extension, Kern County, will lead the next webinar on October 9, 2024 (3 – 4 p.m.).  She will discuss carrot production in California’s Central Valley, the biggest producer in the U.S. Dr. Sidhu will include major pest challenges and pest management with research findings for management especially for root knot nematodes, Alternaria leaf blight and cavity spot. One DPR CE unit (other) and one CCA CE unit (IPM) are pending. In order to qualify for credit, a final exam will be given and must be passed with a 70% or higher. Register to attend this free webinar HERE.

  • UCANR Fall Citrus Grower Meeting, Oct. 9

    A group of UC experts are gathering for a “Fall Citrus Meeting” on October 9, 2024, (8 a.m. to 2 p.m.) at the Lindcove Conference Room at the Lindcove Research & Extension Center in Exeter, CA. This is a great opportunity for citrus pest control advisors and growers to learn about ongoing research efforts, and meet with UC experts, Ass. Ag Commissioner about current laws and regs, and hear about ongoing efforts to mitigate ACP/HLB on ground from grower liaisons. 4.5 Continuing Education Units pending approval.  Register to attend HERE. See the Agenda below:

  • UC ANR Publishes First-Ever Olive Production for Oil Manual

    Facing a deluge of lower-price products from Europe, the California olive oil industry is doubling down on its clear-cut competitive edge: the consistent and bona fide quality of its oil.

    “Olive Production Manual for Oil,” a new book published by University of California Agriculture and Natural Resources, aims to help California olive growers maximize that advantage.

    “It’s a tough market to compete in, but I think the way to win for California is to compete on quality,” said book co-editor Selina Wang, a UC Cooperative Extension specialist in the UC Davis Department of Food Science and Technology. “The quality of California olive oil is unmatched, but you can’t make good quality olive oil with bad fruit, so the goal is to get more fruit from the trees – and for the fruits to be high-quality fruit.”

    The 273-page manual, available for purchase online, is the first of its kind in the U.S. While some parts of the book are specific to California (which grows nearly all of the olives for domestically produced olive oil), most of the material would be useful to producers in other states, Wang noted.

    “Through our conversations with growers, it became clear to us that a manual like this – not a scientific publication but a manual that is easy to follow, written in language that is accessible, and with pictures and illustrations – would be really helpful to the growers,” she said.

    Growth of California olive oil industry necessitated creation of manual

    The new oil olive production manual, published by UC ANR, is the first of its kind in the U.S. Copyright UC Regents

    Aside from a book focused predominantly on table olives and another on organic olive production (by UCCE farm advisor emeritus Paul Vossen), there was no one-stop, comprehensive resource on the bookshelf for oil olive growers. The need for such a manual had become more acute as oil olives replaced table olives in California orchards during the last 20 years.

    Whereas harvesting by hand was historically cost-prohibitive, the introduction of super-high-density planting systems in 1999 made oil olive production more economically feasible. Mechanical pruning and harvesting of new cultivars (Arbequina, Arbosana and Koroneiki) – specifically bred for these densely planted orchards – led to the rapid expansion of oil olives in the state. According to a U.S. Department of Agriculture report, California olive oil production jumped from 2 million pounds in 2006 to an average of 21 million pounds in 2021–23.

    With about 37,000 acres of oil olives planted across California, the Olive Oil Commission of California saw the need to support the production of this manual. Championed by Dan Flynn, founder and executive director emeritus of the UC Davis Olive Center, Wang and co-editor Louise Fergusonoutlined the contents of the book. They then sought out a mix of growers and industry professionals and UCCE advisors and specialists to write its chapters.

    “Most of the information is data-based, from people who are working with the olives,” said Ferguson, a UC Cooperative Extension pomologist at UC Davis. “This is the first data-based olive oil production manual we’ve had.”

    Manual infused with firsthand insights, practical recommendations

    Of the three main varieties planted in super-high-density systems, Arbosana has the most consistent fruit yield. Photo by Dan Flynn; copyright UC Regents

    Hard-earned experience taught growers a valuable lesson that is conveyed in the book – the need to hand-prune. While mechanical pruning helps control the size of the trees, some hand-pruning is still required to allow light to filter to the leaves. Failing to do so leads to a dramatic decrease in yield.

    “That happened in many of the orchards that were inexperienced in these new cultivars and new super-high-density planting systems,” Ferguson said.

    She added that other key topics in the manual include irrigation management in a water-constrained state, nitrogen management, harvest timing and orchard site selection. Choosing a good spot for planting is crucial in this era of extreme climate volatility, Ferguson noted, as olive trees are significantly affected by temperature shocks in spring (fruit set) and fall (harvest).

    For Wang, another overarching theme in the manual is the importance of testing. Testing the soil, water and leaves provides critical data that growers can use to adjust their inputs and production practices for optimal profitability.

    “You may spend a couple hundred dollars on the lab work, but it will pay off, for sure – you’re going to increase the health and productivity of your trees,” Wang explained. “Oil olive growers are paid based on the oil content in their fruit; you not only want to have a lot of fruit on the trees, you want to make sure that your fruit are accumulating oil.”

    California oil olive growers, practices continue to evolve

    Wang and Ferguson hope their book will help California producers compete more effectively in the global marketplace. Currently, about 90% of the olive oil consumed in the U.S. is imported from Mediterranean countries, due primarily to the lower price point. In that region, producers tend to harvest riper olives that produce oil at a greater volume but lesser quality.

    In contrast, California growers harvest earlier and produce oil that is higher quality (with more flavor and more antioxidants) and far exceeds accepted standards for “extra virgin olive oil.”

    According to Wang, California olive oil mills have nearly maximized their efficiency, and the growth opportunity for the industry is in the orchards: to optimize practices to produce more fruit, and to plant more trees. Wang said the new manual can help on both fronts.

    “Just like for other crops, focusing on quality – while increasing efficiency and productivity, and therefore profitability – is the name of the game,” she said.

    Ferguson also stressed that knowledge continues to evolve and urged growers to reach out to the editors and chapter authors with their experiences.

    “Most of the authors are in California and they’re working,” she said. “So if you start to notice things that are different, or you want more information or something is not clear, the authors are available.”

    The manual can be purchased at https://anrcatalog.ucanr.edu/Details.aspx?itemNo=3559. — By Michael Hsu, UCANR

  • California Navel Orange Forecast Up from Last Year

    The initial 2024-25 California Navel orange forecast is 78.0 million cartons, up 2% from the previous year. These forecasts are based on the results of the 2024-25 Navel Orange Objective Measurement (O.M.) Survey, which was conducted from June 8 to August 25, 2024. Estimated fruit set per tree, fruit diameter, trees per acre, bearing acreage, and oranges per box were used in the statistical models estimating production.

    This forecast includes production of conventional, organic, and specialty Navel oranges (including Cara Cara and Blood orange varieties).

    Survey data indicated a fruit set per tree of 414, up 24% from the previous year. The average September 1 diameter was 2.063 inches, down 5% from last year. Bearing acreage is estimated at 110,000, which results in a forecasted yield of 709 cartons per acre.

    CARA CARA PRODUCTION FORECAST

    Cara Cara variety production is forecast at 9.0 million cartons. Survey data indicated a fruit set per tree of 301, up 10% from the previous year and 15% above the five-year average of 262. The average diameter on September 1 was 2.142 inches, 2% below the previous year and 2% below the five-year average of 2.180 inches.

    SURVEY SAMPLE

    A sample of 804 Navel orange groves was randomly selected proportional to county and variety bearing acreage, and 749 of the groves were utilized in this survey. Once a grove was randomly chosen and grower permission was granted, two trees were randomly selected.

    For each randomly selected tree, the trunk was measured along with all connected branches. A random number table was then used to select a branch, and then all connected branches from the randomly selected branch were measured.

    This process was repeated until a branch was reached with no significant limbs beyond this point. This randomly selected branch, called the terminal branch, was then closely inspected to count all fruit connected to this branch, as well as all of the fruit along the path from the trunk to the terminal branch. Since each selected path has a probability of selection associated with the path, a probability-based method was then applied to estimate a fruit count for the entire tree.

    In the last week of the survey period, fruit diameter measurements were made on the right quadrant of four trees surrounding the two trees of every third grove. These measurements were used to estimate an average fruit diameter per tree. Of the 749 utilized groves, 126 were in Fresno County, 425 were in Tulare County, 171 were in Kern County, and 27 were in the remaining counties.

    SURVEY HISTORY

    A Navel Orange Objective Measurement Survey has been conducted in the Central Valley every year since the 1984-85 crop year, except for the 1991-92 season due to a lack of funding. The data from the first two years were used for research purposes in developing crop-estimating models. The Cara Cara forecast was undertaken at the request of the California Citrus Advisory Committee starting with the 2018-19 crop year.

    Beginning in the 2023-24 crop year, only state level forecasts will be published, and the Central Valley forecasts will be discontinued.