California Ag Network

Category: Nut Industry

  • Preventing Bacterial Blast Damage in 2026

    Though our weather outlook for the next couple of months is leaning toward warmer weather than usual, a cold snap during bloom and leaf-out could cause significant bacterial blast damage. Make a plan now in case of bad weather.

    The Bottom Line:

    • Bacterial blast can be a problem when cold, wet weather coincides with bloom or leaf-out.
    • Copper resistance is common: spraying copper is ineffective for preventing blast.
    • Frost protection is the most economical prevention option and will help prevent damage from both frost and bacterial blast.
    • The antibiotic kasugamycin (Kasumin®) is effective for preventing blast when applied up to 6 days before cold, wet weather. It is available this year under Section 18 exemption (Feb 1- April 15), consult with your PCA regarding rates and timings.

    The Details:

    Pseudomonas syringae can infect all aboveground parts of an almond tree, causing bacterial blast of the leaves and flowers. Pseudomonas is everywhere, so weather conditions are the factor driving this disease. Freezing cold, wet weather favors this disease. Pseudomonas is spread by water hitting the tree. If this occurs during frost, Pseudomonas can enter the tree through cells broken by frost damage. Trees are especially susceptible to frost damage during bloom and leaf-out, when tender new growth is exposed to cold weather.

    Preventing infection by Pseudomonas is the only way to control bacterial blast. Frost protection is the most inexpensive strategy: if the trees are not damaged by frost, Pseudomonas will not have a way in to cause disease. As a second line of defense, kasugamycin (Kasumin®) is effective to prevent bacterial blast when applied no more than 6 days before cold, wet weather. For this spray, complete coverage is crucial: all the tender new growth must be covered in a protective layer of the antibiotic for it to be effective. Any tissue left uncovered will be unprotected. Kasugamycin recently received a Section 18 for use in almond between February 1 and April 15, 2026. If the weather warrants treatment, kasugamycin can be used as a preventative spray up to two times during the temporary use window. Current work by UC researchers shows that copper-resistance is common in Pseudomonasthroughout the state. In some cases, mixing mancozeb with the copper may provide some level of control, but research shows that this mixt ure is not as effective as kasugamycin and can cause phytotoxicity.

    For more information on bacterial blast, check out these articles at www.sacvalleyorchards.com

    Bacterial blast/canker: What do we know?

    Bacterial Blast and Canker

    — By Jaime Ott, UC Extension Tehama, Shasta, Glenn and Butte Counties

  • Best Practices for Nighttime Applications

    Honey bee health remains a top priority for almond growers as bloom approaches. According to the Almond Board of California’s Honey Bee Best Management Practices (BMP), one of the most effective ways to reduce bee exposure to crop protection materials is to schedule applications during the evening or nighttime hours, when foraging bees have returned to their hives. The BMPs also emphasize strong communication among growers, beekeepers, PCAs, and applicators to ensure everyone involved knows when applications will occur and can coordinate accordingly.

    Working after dark though can be dangerous. While doing so helps to reduce pollinator exposure to applications, it also requires growers to operate within California’s specific nighttime safety regulations.

    Understanding Nighttime Safety Requirements

    California’s Outdoor Agricultural Operations During Hours of Darkness standards apply to all agricultural work occurring between sunset and sunrise. These regulations require growers to ensure adequate visibility throughout the work environment. Orchard areas, walkways, and paths to restrooms must meet minimum illumination levels measured directly where workers walk or perform tasks.

    Additionally, equipment such as trucks, tractors, and other self-propelled machinery must have headlights and rear lights capable of illuminating at least 50 feet ahead and behind, improving safety for both operators and ground crews. These lighting requirements help reduce the risks posed by diminished nighttime visibility, especially when work involves multiple people and moving equipment.

    Preparing Crews with Pre‑Shift Safety Meetings

    Before each night shift begins, California regulations require supervisors to hold a safety meeting to review important site information. Workers must be informed of the locations of restrooms, drinking water, designated break areas, nearby bodies of water, and high traffic zones. Because nighttime conditions can make familiar surroundings more difficult to navigate, these meetings ensure workers can safely move around the orchard and are aware of any specific hazards.

    Employers are also required to provide and ensure the use of Class 2 high‑visibility garments, helping equipment operators maintain awareness of workers on the ground. Review the Outdoor Agricultural Operations During Hours of Darkness fact sheet for more information and all of the requirements.

    A Unified Approach for Safer, More Effective Operations

    When growers pair honey bee protection guidelines with the required safety measures for nighttime work, the result is a more sustainable and efficient approach to orchard management. Bees remain safely inside their hives during nighttime applications, greatly reducing their exposure to crop protection materials. At the same time, crews can work confidently and safely under proper lighting, with clear preparation and the right equipment.

    As bloom approaches, these practices support the long‑standing commitment of the almond industry to safeguard both pollinators and people. This thoughtful balance ensures that orchards remain not only productive, but also safe and welcoming places for the bees that sustain them. To learn more about protecting pollinators, download the ABC Honey Bee Best Management Practices guide. — Article and image courtesy of Almond Board of California

  • Scientists Offer Breakage Insights with Potential Benefits for Crops

    When pistachio hulls split before the nuts are harvested, insects and fungi can get inside, damaging the nut, costing farmers money and contaminating the nuts. About 4% of the overall crop experiences hull split, but some cultivars can split as much as 40% under certain conditions.

    For the first time, scientists at the University of California, Davis, are seeking solutions for California’s $2-billion-a-year pistachio industry. New research reveals how the hull is built and how cell walls in certain layers break down, along with the genes and corresponding mechanisms that spark and control those changes.

    Pectin, a component of cell walls, makes fruit skin strong in part by keeping cells hitched to each other. In pistachio hulls, the composition of pectin changes as the hull ripens, causing the cells to come unhitched. This leads to cracks and tears in the hull.

    In the Journal of Experimental Botany, recent Ph.D. graduate Shuxiao “Susan” Zhang, a student in the lab of Department of Plant Sciences Professor Georgia Drakakaki, identified genes that control how cell walls change as the fruit ripens, leading to the hull breaking down. The research will help breeders select for traits that will make the hulls less vulnerable to tearing and cracking.

    “This is the first time anyone has studied the pistachio hull at the anatomical and cellular level while also looking at gene expression and physiological data,” Drakakaki said. “Susan really got into the details of how the hull is built with different layers and how the cells in those layers are of different sizes. The layers respond differently to changes in pectin, and that causes the hull to split in different ways.”

    Zhang built on the work of two more scientists in the department and their teams. Grey Monroe, an assistant professor, and Barbara Blanco-Ulate, an associate professor, assembled a reference genome of Pistacia vera ‘Kerman,’ the leading female pistachio cultivar in California. They also defined the stages of the nut’s growth and the characteristics at each stage. Their work was published last year.

    A Model for Fruit Split in a Variety of Crops

    Over three years, the team took samples of pistachio hulls from trees in a commercial orchard near Fresno and at the Wolfskill Experimental Orchard, operated by UC Davis near Winters, Calif. They worked with the most common varieties grown in the state, including Kerman, Golden Hills and Lost Hills. They took samples from trees at different points late in the hulls’ development, stretching over several months.

    Using special imaging tools and techniques, Zhang and her team measured hull thickness and cell size, and they counted hulls that were intact, tattered, cracked or both. They also measured how well cells in the hull were sticking to each other, and in each sample counted the cells that had come unhitched.

    Then, the team pulled out RNA from the samples to learn which genes were being expressed at different stages as the hull develops and breaks down. They found that key genes express differently as that process unfolds.

    Since all hulls were intact at 91 days after flowering, Zhang and team reasoned that fruit ripening may be linked with hull split. So, the team also examined the genes — including those involved in pectin modification — that change the cell wall as the fruit ripens. Researchers discovered that cells in the interior layer of the hull expand, while cells in the exterior layer tend to stay the same size. This, in combination with changes in the cell wall, led to different types of hull breakdown.

    “This is one of the major novelty factors for our paper,” Zhang said. “Loads of people have looked at pectin in all kinds of fruits, but not many people have observed that, depending on which cell layer you’re in, the pectin, cell size and so on will change differently during ripening.”

    The physics of forces operating within the cell layers and humidity also influence degradation of the hull, Zhang found.

    Because pistachio hulls are the fruit of the tree, even though we eat the seed, the research has applications for many non-berry fruit crops, Zhang concluded.

    The California Pistachio Board funded most of this research, with additional support from the United States Department of Agriculture’s National Institute of Food and Agriculture, the James Monroe McDonald Endowment and the University of California Agricultural and Natural Resources. — By Trina Kleist, UC Davis Department of Plant Sciences

  • Almond Conference Updates Growers on Best Practices for Bees & Pollination

    As almond growers prepare for pollinating their orchards — one of the most important tasks for establishing the new crop — here are insights from the Almond Conference to consider.  A “Honey Bees & Pollination” panel was moderated by Josette Lewis of the Almond Board of California (ABC).

    Hives Per Acre for Self-Fertile Cultivars: Elina Niño

    Following a string of bee losses over the past twenty years, 2025 was especially severe, with a 62% loss.  According to Elina Niño, apiculture scientist at UC Davis, the losses are becoming unsustainable.

    Niño pointed out that, in spite of having only 0.6 million of the 2.5-2.7 million colonies in the US, California ranks third in honey production, after North and South Dakota.

    Niño conducted a study of the pollination needs of self-fertile cultivars.  She excluded bees from some trees and for others used one or two hives per acre.  She counted the number of bees per flower per hour and after harvest she measured the kernel mass of 100 nuts per tree.

    The results showed that the number of visits per flower was similar for one hive as for two hives per acre.  Although the trees set more nuts and yielded more weight when one or two hives were present, kernel mass was higher where bees were excluded, presumably due to spreading the trees’ resources over fewer nuts.

    State of the US Commercial Beekeeping Industry: Matt Beekman

    The biological state of the beekeeping industry is precarious, according to Matt Beekman, a beekeeper based in Hughson, California who spends summers in North Dakota.  He presented a biological and financial State of the Beekeeping Industry report.

    Parasites & Pathogens: Varroa Mites & Viruses

    The varroa mite parasite continues to afflict beehives.  Reproducing quickly, the mites vector viruses that then spread from bee to bee in the densely populated hive.  The viruses can also spread in semen.  Area-wide applications of miticide help manage the mites.

    Only one chemical had been approved to suppress varroa mites since 2005.  That chemical, Amitraz, was registered for beehive use in 2013 in California, the last state to do so.  Some softer chemistries are available, but they are temperature dependent.

    California approved two new products in 2025, one oxalic acid-based and the other RNA-based.  They are expensive, though, costing $74 per colony per year.

    Nutrition: Where Have All the Flowers Gone?

    Each hive needs about 50 pounds of pollen and 100 pounds of nectar year.  With fewer acres enrolled in the federal Conservation Reserve Program, pollen and nectar may be scarce.

    Alternatively, almond growers can plant cover crops in the orchards to meet the need.  Seeds for Bees supplies free, appropriate cover crop seeds the first year and a discounted price the second year.  Many growers continue buying the seeds annually after seeing how effective they are.

    Pesticides: No to Organosilicon Adjuvant

    Used to amplify the effectiveness of pesticides, organosilicon surfactants harm bees.  Growers should ask their PCA to use one of the available alternatives instead.

    Beekman said that fungicides need to be sprayed during bloom, but advised using no tank mixes, adjuvants or insecticides during bloom, and applying fungicides in the early evening when bees are not flying.

    Financial Snapshot

    The net profit for beekeepers in 2024 was $11 per hive.  Overtime wages adversely impacted beekeepers, who need workers to do nighttime maintenance and overnight travel.  US honey production is declining due to fewer locations where bees can be placed to collect nectar.  The bees need more access to public land.

    Meanwhile, honey imports are increasing.  Imported honey is sometimes cut with synthetic sugar syrups.  Since honey is one of the few commodities for which the US does not have a standard definition, ambiguity and adulteration occur.

    India is now the largest exporter of honey into the US, with prices of $0.99-1.08/lb.   The US price is $2.69/lb., and the yield is declining.   

    Endangered Pollinator Species: Alexi Rodriguez

    Some insect species have been proposed for endangered species status for the first time, according to Alexi Rodriguez of the Almond Alliance.  One such insect is the monarch butterfly, which has little overlap with agriculture except for coastal sites in winter.

    A 2018 petition proposed adding four bumblebee species.

    Rodriguez said that if growers take reasonable, research-based steps to support pollinators, they will be immune to prosecution if incidental harm occurs.  The steps include using IPM (Integrated Pest Management) and planting pollinator habitat.

    Questions from the Audience

    Q: Is it worth getting mason bees to complement honeybees?

    A: Yes — blue orchard bees (a type of mason bee) — but you have to contract it separately.  They fly in colder temperatures and in rain.

    Q: Was there a bee shortage in 2025?

    A: That was not studied, but growers were saying that they did not get the number of frames they contracted for.  It’s possible that insufficient bees caused the lower yield last year, because everything else was good in 2025.

    Q: What about indoor cold storage of bees in empty warehouses to break the varroa mite cycle?

    A: It did not go well when tried in Kern County.

    Q: Does supplementing the almond orchard with pollen help with pollination?

    A: There is no research on that, but it is unlikely to help based on flower anatomy and the need for insects to get into the blooms to move pollen.

    Q: Does it help to move hives around during pollination?

    A: Yes, but it is a tradeoff economically due to the cost of labor to move the hives.  The most important variable is having morning sun on the hive to warm the bees enough to fly.  The bees will fly over the entire acre once they are warm.

    Q: What is a fair contract between grower and beekeeper?

    A: Eight frames average per hive; four to five frames minimum, 60% coverage.

    Q: Do herbicides impact bees?

    A: There is no research on that, but herbicides are not needed during bloom anyway.

    For more information about preparing for pollination, see Honeybee ABC.  – By Nancy Power, PhD, Assistant Editor, Pacific Nut Producer

  • Walnut Alliance of California Provides Advocacy for Growers

    Walnut growers in California have a new voice advocating for them in politics, trade and more. In an interview with Matthew Malcolm on California Ag Network, Chris Zanobini and Donald Norene talk about the work and mission of the Walnut Alliance of California. Watch this quick video and learn more in Pacific Nut Producer Magazine.

  • Nematode Management Tips for Tree Nut Growers

    Nematodes can be a headache for growers. Luckily, ways to manage them are being researched and developed. At the Malcolm Media Tree & Vine Expo and in an interview with Matthew Malcolm on California Ag Network, Andreas Westphal with UCCE Riverside discusses nematode management. Watch this quick video and learn more in Pacific Nut Producer Magazine.

  • High Demand Means Bright Outlook for Pistachio Industry

    Pistachio harvests were slightly smaller than initially anticipated, but still set record numbers. Optimism is also high with rising demand for pistachios. At Malcolm Media’s Grape, Nut & Tree Fruit Expo and in an interview with Matthew Malcolm on California Ag Net, American Pistachio Growers President/CEO Zachary Fraser discusses the state of the pistachio industry. Watch this brief video and learn more in Pacific Nut Producer Magazine.

  • Walnut Industry Growing Momentum with Quality Crop and Record Sales

    The walnut industry is building momentum as indicators suggest one of the best crops growers have had in recent history. Committed sales are also at record numbers. At Malcolm Media’s Tree & Vine Expo in Turlock and in an interview with Matthew Malcolm on California Ag Network, California Walnut Board Commission CEO/Executive Director Robert Verloop discusses the state of walnut growers. Watch this quick video and learn more in Pacific Nut Producer Magazine.

  • Hazelnut Farmer Finds Clever Way to Handle Squirrel Trouble

    Squirrels can be a serious headache for nut growers, who often have to come up with their own ways of catching and getting rid of them as rodenticides are not always an option. Oregon hazelnut grower Ken Baker talks to Matthew Malcolm with Pacific Nut Producer about the way he has learned to trap squirrels at his farm. Watch this quick video and learn more in Pacific Nut Producer Magazine.
    Please thank this video’s sponsor George Packing Company for their industry support.

  • At Farm Bureau Convention in California, Secretary Rollins Announces Dairy Margin Coverage Expansion and Section 32 Purchases of Specialty Crops

    This week at the 107th American Farm Bureau Federation Convention in Anaheim, CA, U.S. Secretary of Agriculture Brooke L. Rollins announced expanded enrollment for 2026 Dairy Margin Coverage (DMC) program and new Section 32 commodity purchases that will result in more healthy, U.S. grown food in the hands of Americans. Following the convention, Secretary Rollins also met with specialty crop producers at a local strawberry farm to discuss workforce needs and the Trump Administration’s recent wins related to significantly cutting the cost of H-2A labor for California farmers.

    Secretary Rollins and former California Ag Secretary A.G. Kawamura at his strawberry farm in Irving, California.

    “President Trump is making historic investments in the farm safety net and today’s announcement is one more action that supports our dairy producers by managing risk and strengthening markets so they can continue to provide wholesome nutrition for Americans,” said Secretary Brooke Rollins. “The Trump Administration will continue to stand with America’s farmers as the farm economy recovers from years of neglect under the last administration. Our mission to Make America Healthy Again continues after the recent release of the Dietary Guidelines for Americans 2025-2030 announcement, with the upcoming purchase of U.S. grown food that will reach those in need, all while benefitting American farmers facing unfair actions from foreign competitors.”

    OBBBA Improves DMC Coverage and Premium Fees

    Secretary Rollins announced the enrollment period for the Dairy Margin Coverage (DMC) program for the 2026 coverage year, an important safety net program that provides producers with price support to help offset milk and feed price differences. Starting January 12, 2026, dairy producers can enroll in DMC. The enrollment period ends February 26, 2026. The One Big Beautiful Bill Act (OBBBA), signed by President Donald J. Trump on July 4, 2025, reauthorized DMC for calendar years 2026 through 2031 and provided substantial program improvements, including establishing new production history and increasing Tier 1 coverage.

    The OBBBA increased DMC’s Tier 1 coverage level increased from five million pounds to six million pounds. All dairy operations that elect to enroll in DMC for 2026 will establish a new production history. Existing dairy operations that started marketing milk on or before January 1, 2023, will use the higher of milk marketings for the years of 2021, 2022, or 2023. New dairy operations starting after January 1, 2023, will use their first year of monthly milk marketings, even for a partial year. Milk marketing statements or production evidence are required to establish a production history.

    Dairy operations also have the option to lock-in coverage levels for six years (2026-2031) with premium fees discounted by 25%.

    DMC offers different levels of coverage, including an option that is free to producers, minus a $100 administrative fee. To determine the appropriate level of DMC coverage for a specific dairy operation, producers can use the online dairy decision tool.

    For more information visit the DMC webpage or contact your local USDA Service Center.

    Agricultural Marketing Service Section 32 Purchases

    Secretary Rollins also announced USDA’s intent to purchase up to $80 million in specialty crops from American farmers and producers to distribute to food banks and nutrition assistance programs across the country. These purchases are being made through USDA’s authority under Section 32 of the Agriculture Act of 1935 and will assist producers and communities in need. With this action, the Trump Administration is bolstering American prosperity by supporting American agriculture, rural communities, and those in need of nutrition assistance.

    The Agricultural Marketing Service (AMS) continuously purchases a variety of domestically produced and processed agricultural products. These “USDA Foods” are provided to USDA’s Food and Nutrition Service (FNS) nutrition assistance programs, including food banks that operate The Emergency Food Assistance Program (TEFAP), and are a vital component of the nation’s food safety net.

    USDA AMS will purchase up to $80 million of the following commodities:

    •Almonds: $20M

    •Grape juice: $20M

    •Pistachios: $20M

    •Raisins: $20M