California Ag Network

Category: Ag Economics

  • Prepare to Prevent an Autumn Freeze from Damaging Walnut Trees

    Autumn freeze damage in walnuts can occur when trees experience freezing temperatures prior to going into dormancy. In recent history, Sacramento Valley growers experienced this most severely in 2018, and since then, many have implemented management practices to prevent widespread damage.

    Symptoms of freeze damage can include:

    • Late leaf-out in affected limbs
    • Weak or dead terminal budwood and smaller upper limbs (mild/moderate damage)
    • Major limb death, mainly in the upper and exposed portions of the tree, and/or apparent whole tree death (severe damage)
    • Darkened or orange-tinted wood, with gray/black streaking in the cambium underneath
    • Sunburn on damaged limbs, usually on south- and west-facing sides

    This past spring (2024), growers in Sutter, Yuba, Yolo, and Tehama counties reported symptoms of freeze damage, likely from an early autumn freeze that occurred near Halloween. If you noticed any of these symptoms in your orchards this past spring or are aware of cold pockets in certain areas/fields, consider the following steps to prevent another year of freeze damage.

    Preventative management:

    Increase soil heat storage:

    1. For young trees, it’s best to cut off N applications by mid-August to prevent tender new growth that is most vulnerable to freeze damage. Also, withhold irrigation starting in early to mid-September to set a terminal bud on the trunk (Figure 2). After the terminal bud has set, resume irrigation to avoid tree stress and defoliation, without the fear of pushing tender new growth.

    2. For mature trees, cut off nitrogen (N) applications by the beginning of September. Terminal buds may set as a positive side effect of the water cutoff done ahead of harvest to avoid shaker injury.

    Increase soil heat storage:

    3. Maintain short groundcover during autumn frost season, beginning mid-October. Keeping groundcovers cut to 2 inches or less during frost season allows sunlight to reach the soil surface, increasing soil heat storage for a warmer orchard through the night. Recently cultivated soil has many air spaces, low heat storage capacity, and low heat conductivity resulting in colder minimum temperatures. The ground surface must be moist for bare ground to be the warmest (see steps 4 and 5).

    4. Trees that remain water-stressed after the heat of summer are the most vulnerable to autumn and winter freeze damage. If there has not been adequate rainfall by mid-October for young orchards, or immediately after harvest for mature orchards, begin irrigating to refill the soil profile.

    5. Water-filled spaces in the soil conduct and store more heat than empty air spaces. Once the soil profile has been refilled, the top several inches of soil are the most important for freeze mitigation and should be kept at field capacity (not saturated/ponding) if possible. Either a dry surface crust on one extreme or a frozen sheet of ponded water on the other extreme will both hinder the re-radiation of stored daytime heat during the night.

    6. Continue to actively monitor soil moisture and freeze predictions in November and December (until trees are acclimated to frost – see note below). Since freeze events are variable depending on location, monitoring each block remotely with a freeze alarm makes good sense. If a freeze is predicted and the soil is dry, irrigate to wet the soil 2 to 3 days before a freeze event to fill the air spaces so the soil will store more heat. Light irrigation to moisten a dry soil surface the morning before a freeze will help obtain the greatest heat storage for re-radiation at night (as long as there is no standing water during the freeze event).

    Active irrigation during freeze event:

    7. Some growers with the ability to actively irrigate during sudden autumn freeze events have reported success in preventing damage. With active irrigation, heat is given off as water converts from liquid to ice. This occurs during the coldest hours of the early morning of the freeze event and is the reason higher flow rates are needed to more successfully manage frost events.

      • We know from work in almonds that active frost protection with solid set irrigation can achieve as much as 4 degrees protection if your system can run 40 gpm/ac.
      • With micro-sprinkler irrigation, 1-2 degrees of warming can be achieved with at least 30 gpm/ac. 25 gpm/ac has been shown to be enough to keep sprinkler heads from freezing.

    Painting:

    8. In addition to water management, painting young trunks and shoots white can minimize damage if applied as soon as possible after a freeze. Research by UC Walnut Specialist Bruce Lampinen has shown painting after leaf fall with white interior latex paint diluted 50% with water minimizes damage to shoots and buds, especially on the south-west side of the tree. The paint moderates large day-to-night temperature fluctuations after sunny winter days.

    Treatment:

    If you suspect freeze damage occurred, cut into the branches shortly after a freeze event and check the tissue for drying or browning. Swift action in the week after a freeze event can significantly decrease damage. If you don’t paint early, painting trees after a freeze can still help decrease severe damage. Wilbur Reil, Farm Advisor Emeritus, found that when trees were painted a week after a freeze event 18% showed damage, compared with 46% damaged in the unpainted trees. Painting any parts that may be damaged should improve recovery and protect against winter sunburn of affected tissue.

    New growth typically occurs below the damaged/dead locations. Dead wood should be pruned out later in the season (mid-summer), after the tree has fully leafed out, to reduce potential colonization sites by Bot or Phomopsis. In young trees with significant freeze damage, remaining limbs or new limbs may have to be trained as new scaffolds.

    Potential causes:

    In “normal” years, the combination of short days, gradually dropping fall temperatures, and rainfall pattern allows trees to go into dormancy in a stepwise pattern (2021 and 2022 in Figure 3 below). In years where we’ve received more reports of autumn freeze damage, there have been large differences in daily high and low temperature (2020), and sudden drops to freezing temperatures prior to trees reaching full dormancy (2020 and 2023).

    As temperatures drop into the low 30s °F and days shorten, carbohydrates move from leaves to wood and starch converts to soluble sugars. Slow cooling is needed to promote starch degradation into sugars, which act as “antifreeze” to protect cells from freezing, as does adequate soil moisture, which keeps cells hydrated. When temperatures suddenly and prematurely drop below 32°F before the acclimation process is completed, carbohydrate movement is likely disrupted and trees are susceptible to freeze damage.

    Unfortunately, we do not know how many frost/mild freeze events are required to sufficiently acclimate trees in autumn. So far, growers that were previously hit hard by fall freeze events have reported success in avoiding subsequent freeze damage by having frost alarms ready and turned on by October 15, completely rehydrating trees after harvest, and actively irrigating during freeze events. Eventually, once mature healthy trees are fully dormant, they can tolerate temperatures to the low 20s °F or below. — By Clarissa Reyes, Orchards Advisor, Sutter-Yuba, Butte & Placer Counties, and Luke Milliron, UCCE Farm Advisor Butte, Glenn & Tehama Counties

  • 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

  • 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.

  • New Project Aims to Use Farm Waste to Fuel Bioeconomy

    In California’s Northern San Joaquin Valley, crop leftovers such as almond shells, fruit peels and orchard trimmings can potentially be converted into sustainable bioproducts and biofuels – with the right technology. The philanthropy Schmidt Sciences’ Virtual Institute on Feedstocks of the Future, which supports replacing fossil feedstocks with renewable biomass sources, has awarded new funding to a group investigating how to make better use of the diverse agricultural waste in the region.

    “This is an important project for California as it quantifies the diverse ‘ingredients’ in the North San Joaquin Valley available to fuel the emerging biomanufacturing industry in the state,” said Gabe Youtsey, chief innovation officer for the University of California Agriculture and Natural Resources. “This foundational work will kickstart a completely new innovation bioeconomy in the Central Valley that will create new high-paying jobs for our communities and support a resilient food and agriculture industry through circular biomanufacturing.”

    Circular biomanufacturing is a process that uses waste streams as raw materials to create new products.

    “Circular means taking waste streams from agriculture such as almond shells or grape pomace, forest waste or food processing waste and using that material as the ‘feedstock’ in a fermentation tank to create new bioproducts,” Youtsey explained.

    The group, “Building the Circular Bioeconomy in the North San Joaquin Valley” or BioCircular Valley, is co-led by the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), UC Berkeley, and BEAM Circular, with partners at UC Merced, UC Agriculture and Natural Resources, the Almond Board of California and USDA Agricultural Research Station in Albany.

    “California has this incredible diversity of materials, but they aren’t well understood – and this makes it difficult to know how to extract the most value out of them,” said Corinne Scown, a senior scientist at Berkeley Lab and UC Berkeley and one of the project leads. “We want to characterize them and make that information available so companies can more easily figure out which feedstock is a good match for them, and then use that agricultural residue to make everything from bio-based polymers and chemicals to sustainable materials and aviation fuels.”

    One of the group’s goals is to build a publicly accessible database and user-friendly map full of information about different feedstocks, the raw plant materials and biomass that can be broken down and used to make bioproducts. That includes where feedstocks are located, when they are available, how they are currently disposed of, how they perform in different bioreactors, how much sugar or lignin they contain, whether they can be processed with other feedstocks, their greenhouse gas footprint, the potential cost, and much more.

    UC ANR’s role is to collect data on available feedstocks from forest, agricultural and food processing byproducts, as well as municipal waste streams through sampling and observation.

    “We will do this through the extensive knowledge and relationships we have with the California agriculture industry in the North San Joaquin Valley,” Youtsey said. “UC ANR will also support industry outreach as new ‘conversion’ technologies are developed, to pilot them with California growers and processors.”

    The project will also test ways to improve the flexibility of the conversion process, which breaks down feedstocks to prepare them to make bioproducts. Researchers will apply artificial intelligence to their lab-generated data to improve predictions of how feedstocks can be processed most efficiently or blended together. Being able to use the same technique on different (or mixed) kinds of plant matter would open up ways for companies to make bioproducts more easily.

    “Our region has a fantastic combination of diverse and large-scale agricultural activities alongside manufacturing expertise, making this a great place to scale up bioeconomy innovation,” said Karen Warner, CEO of BEAM Circular. “This project will allow us to reduce barriers to using our region’s abundant waste streams in more sustainable and valuable ways, so that we can create the products that people need with renewable inputs that are better for the planet.”

    The project builds on ongoing efforts to establish biomanufacturing capabilities in the northern San Joaquin Valley, which includes San Joaquin, Stanislaus and Merced counties. Providing better data on how to convert the valley’s millions of tons of agricultural waste into valuable products may spur biomanufacturing companies to build facilities nearby, minimizing how far the raw materials have to be moved and generating new jobs.

    “This project is designed to benefit a region that has massive potential, but so far has been economically left behind, and to develop a new industry that can provide improvements in air quality, water quality and greenhouse gas emissions as well as significant opportunities in economic equity and the creation of new jobs,” said Blake Simmons, director of Berkeley Lab’s Biological Systems and Engineering Division and the BioCircular Valley project lead.

    “This kind of research started as basic science, and now we’re bringing information and solutions to people who can use them. And the knowledge generated through this project will advance not only the ability of the NSJV to make use of its own regionally available future feedstocks, but will also accelerate the understanding of feedstocks relevant across California and across the U.S.”

    The new funds for the project come from the Virtual Institute on Feedstocks of the Future, a partnership between Schmidt Sciences and the Foundation for Food & Agriculture that supports collaboration on research to transform biomass into alternative feedstocks for biomanufacturing. The award is one of five, which total $47.3 million over five years. It is expected that the five teams will collaborate to share best practices and knowledge to boost the bioeconomy at the national level.

    “We are grateful for Schmidt’s generous support that will help deploy advanced technologies on the ground,” said Alicia Chang, interim president of Berkeley Lab Foundation. “The foundational research and expertise developed through work for the Department of Energy sets the stage for this team to apply their capabilities to bring jobs and lift the community and the economy in the Northern San Joaquin Valley.” — By Lauren Biron & Pam Kan-Rice, UCANR

  • Visual ID Guide to Help Manage New Almond Pest

    Since the first reports of a new almond pest – the carpophilus beetle (Carpophilus truncatus) – came in during fall 2023, it has become clear that the beetle is widely dispersed across the San Joaquin Valley.

    “My lab has identified infestations from every county in the San Joaquin Valley; we have found infestations in both almonds and pistachios, and we will likely find infestations in walnuts this fall,” said Houston Wilson, a University of California Cooperative Extension entomology specialist at UC Riverside. The California Department of Food and Agriculture has confirmed the beetle’s presence in Stanislaus, Merced, Madera and Kings counties.

    Historically a major threat to almond production in Australia, the beetle – as larvae and adults – feeds directly on the nut kernel. In California, some almond growers have lost 10 to 15% of their yield – a “significant economic loss,” according to Jhalendra Rijal, University of California integrated pest management (IPM) advisor for the region. Given the prominence of almonds as a commodity, even a 1% overall reduction statewide represents an approximately $70 million loss.

    “This year there has been a lot more reports from PCAs [pest control advisers]; they’re sending me the pictures of the damage and beetles,” said Rijal, noting that the increase is likely due to greater awareness of the pest.

    To help almond growers identify the carpophilus beetle and develop management plans, Rijal, Wilson and their IPM colleagues have put together a visual ID guide for the beetle and the damage it causes, as well as telltale signs of navel orangeworm (Amyelois transitella) and ant damage. In particular, the experts would like PCAs and growers to differentiate between the carpophilus beetle and navel orangeworm, another key pest in almonds.

    “Even though their way of causing damage looks more or less similar, we’re dealing with two different types of insects,” Rijal explained. “One is a Lepidoptera moth [navel orangeworm], and the other one is a beetle – many of the management practices and biological controls would be different for these two different things.”

    TOP: Both carpophilus beetle adults and larvae feed on the kernel and cause damage characterized by fine powdery frass and nutmeat, a white-creamy color with some webbing. Often, large numbers (more than 10) of adult and larvae are found per nut. BOTTOM: Navel orangeworm larvae cause damage characterized by thicker frass and silky webbing entangled with a darker, brownish appearance. Only larvae are present at harvest, usually 1 to 3 larvae per nut. Photos by UCCE Stanislaus IPM team

    To control carpophilus beetle, ‘sanitize, sanitize, sanitize’

    One crucial cultural practice for managing both pests, however, is destroying the remnant “mummy” nuts – the nuts that remain in the orchard postharvest. They serve as overwintering habitat for the carpophilus beetle, as well as its sustenance for the next generation of beetles in spring.

    “The best way to manage this pest is to do the orchard hygiene – continuing the winter sanitation, destroying the nuts that are on the ground and on the tree and on the berms,” Rijal said.

    Based on observations in Australia and locally, carpophilus beetles tend to rely more on mummies on the ground, whereas navel orangeworm generally favors mummies in the tree canopy. Correctly identifying the pest – with help from the new ID guide – enables growers to better target and prioritize their management efforts, Rijal said.

    “What we are strongly emphasizing is that growers need to sanitize, sanitize, sanitize to control both pests,” Wilson added.

    Correct identification of the pest would also prevent unnecessary application of insecticides, as those used for controlling Lepidoptera such as navel orangeworm would be largely ineffective on the beetle.

    Indeed, another insight shared by Australian experts is that the carpophilus beetle cannot be controlled just by insecticide.

    “Insecticides are not very efficient, given the cryptic nature of these beetles; exposing these beetles to the insecticide is very hard,” said Rijal, noting that the beetle spends most of its life cycle protected inside the nut.

    Reporting carpophilus beetle infestation helps researchers

    Mature larva of navel orangeworm (NOW) is 3 to 4 times larger than carpophilus beetle (CB) mature larva. Photo by Jhalendra Rijal

    This harvest season, Rijal advises almond growers to harvest as efficiently as possible, to minimize the number of mummies that need to be cleaned up. And because signs of damage (like damaged hulls and frass) are most obvious during harvest time, Rijal said growers should review the new guide, using the photos and other resources to help identify potential pests.

    If the grower or PCA suspects a carpophilus beetle infestation, they should contact the UCCE farm advisor in their area.

    Scientists are looking to expand their knowledge about this relatively new pest to California. In the coming weeks, for example, researchers are planning to survey for the carpophilus beetle in the Sacramento Valley.

    “Technically it has not been found there, but we suspect that we’ll find it this fall when we go looking for it,” Wilson said.

    Researchers are also collecting samples from infested orchards to better understand the biology of the species, as well as how it progresses through and responds to seasonal and climactic changes. In addition, they are analyzing data from a trial study of an insecticide that might be used as a supplemental control measure.

    “This is our first full season dealing with this insect, and there are still many things we need to understand,” Rijal said. “We are continuing our research efforts on all fronts.” — By Michael Hsu, UCANR

  • 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

  • Investments in Farm-to-School Program Stabilize Farms

    A new report reveals that California farmers participating in the state’s Farm to School Incubator Grant Program are increasing sales of fresh, local and organic produce, meat and dairy products to schools, according to researchers evaluating program impacts. The report found that 57% of the program’s farmers made sales to schools between April and September 2023, representing an average of 33% of their total farm revenues. All food producers funded by the Farm to School Grant Program state that they use or plan to use climate-smart agricultural practices in their operations during the grant period.

    California has made the largest investment of any state in the country in farm-to-school programs, allocating approximately $100 million from 2020 through 2022. The report, authored by an independent group of researchers from UC Agriculture and Natural Resources, UC Berkeley, Food Insight Group, Berkeley Food Institute, and U.S. Department of Agriculture, shows those investments are beginning to pay off beyond increasing kids’ exposure to food education and California-grown fruits and vegetables.

    While existing research shows that kids who engage with farm-to-school programs eat more fruits and vegetables, are more willing to try healthy foods, and even perform better in class, the California farm-to-school evaluation project examines a gap that most farm-to-school research hasn’t addressed: how local purchases from schools affect the agricultural sector and the environment.

    The report found that the investments are flowing primarily to the farmers the state seeks to support through this program: Of the 50 producer grantees evaluated in this report, 42% are owned by people who identify as Black, Indigenous and People of Color, and 62% are owned by women. Nearly all (94%) are small to midsize operations.

    Three producer grantees revealed that the Farm to School Incubator Grant Program funding likely prevented them from going out of business. “This grant … has and will enable us to do things on the farm that would probably take us a decade to do but we’ll be able to do that in one or two seasons. So [it] really moves us forward a lot,” noted one farmer.

    Beth Katz, a lead researcher and executive director of Food Insight Group, said, “Farmers are expanding their relationships with local school districts, increasing their sales to schools, investing in infrastructure and staff, and forming new relationships with food hubs that can help them with the often complex purchasing requirements unique to school food. While we’re still at a very early stage of understanding the impacts of these investments, we’re beginning to see patterns emerge.”

    A Humboldt County farmer noted that food hubs, which are also supported by the grant program, are critical to their success in accessing the school food market: “[The food hub] is really a huge game changer to be able to make that one drop in town, even though it’s an hour away, rather than going to [several school sites] and just making all these little drops. That’s been one of the ways that it’s very . . .appealing to us as a farm to participate.”

    The report also examines the potential for environmental impacts through direct investments in farmers who use climate-friendly farming practices.

    Research shows that kids who engage with farm-to-school programs eat more fruits and vegetables, are more willing to try healthy foods, and perform better in class.

    “I’m inspired by the potential for the farm-to-school program to support farmers using environmentally beneficial practices like reducing pesticides, planting cover crops and growing organic — and to help farmers expand or adopt these practices. It’s essential these farmers have a market for what they grow to see durable environmental benefits,” said Tim Bowles, who is leading the environmental impacts assessment for the evaluation team and is an assistant professor in the Department of Environmental Science, Policy & Management at UC Berkeley and lead faculty director of the Berkeley Food Institute.

    “We’re also seeing farms actually expand their acreage in order to sell to schools, suggesting this is a desirable market. We’re investigating the environmental impacts from these investments, especially for climate,” Bowles said.

    As with many new programs aimed at building out long-delayed infrastructure, school food systems improvement demands a deep-rooted approach.

    The farm-to-school program supports farmers using environmentally beneficial practices like reducing pesticides, planting cover crops and growing organic.

    “The challenges around changing a complex school food system are substantial,” Gail Feenstra, a pioneer in farm-to-school research and co-lead on the project from UC ANR stated. “Decades of research shows the value to children from fresh, locally sourced food. However, what is becoming more clear from this research is that long-term investments in the full farm to school system are crucial. Without regional-level infrastructure, staffing, aggregation and distribution in place to support getting that locally grown food from farms to the schools and kids, we’ll have challenges moving the needle.

    “Fortunately, the state’s strategic and innovative investments in the entire farm to school supply chain – meaning funding for school districts, farmers and also their regional partners, combined with support from CDFA’s regional staff – are beginning to address those long-standing challenges.” — By Haven Bourque, UCANR