Pacific Nut Producer Magazine

Tag: Carpophilus Beetle

  • Almond Day Updates Growers on New Pest, Disease in California

    Late in 2023, California almond growers – responsible for a crop valued at $3.88 billion in 2023 – started to hear about a potentially devastating new pest, the carpophilus beetle (Carpophilus truncatus).

    With virtually no information about this species in California, Jhalendra Rijal and his colleagues spent 2024 investigating its extent in the almond-growing regions of the state and learning from peers in Australia, where the insect has been a persistent scourge for a decade.

    A hullsplit almond showing a large number of carpophilus beetles (Carpophilus truncatus). Photo by Jhalendra Rijal.

    “This year, we at least have the one year of experience with this pest, and we have generated information that is relevant and practical for the growers,” said Rijal, a University of California Cooperative Extension integrated pest management advisor. For example: After an insecticide trial was largely ineffective (likely because the beetle spends most of its life cycle protected within the nut), Rijal has been emphasizing cultural practices like orchard sanitation.

    Sharing those crucial updates is one reason why the annual UCCE North San Joaquin Valley Almond Day is essential for growers, industry professionals and pest control advisers. This year’s event was held on Jan. 21 at the Modesto Centre Plaza.

    During Almond Day 2025, Jhalendra Rijal, UCCE IPM advisor, discusses the differences between Carpophilus truncatus and related beetle species. Photo by Mike Hsu

    “It’s the meeting on everyone’s calendar,” said Rijal, who co-organized the event alongside his UC Agriculture and Natural Resources peers, Brent Holtz and Cameron Zuber.

    With support from Farm Credit, the 2025 Almond Day attracted about 140 people, who heard about a range of best practices on almond production and pest management from six UC experts.

    “This is a great educational tool,” said meeting attendee Ali Arshad, a Blue Diamond grower who operates several ranches in San Joaquin and Stanislaus counties. “I like to come attend their seminars as much as possible; they’re very educational and informative – and very helpful too.”

    Scientists offer advice on managing carpophilus beetle, red leaf blotch in almonds

    Fellow grower Donny Hicks, who has attended 14 Almond Day meetings, concurred about the usefulness of the event. “Everything that was covered today is applicable to what I do,” he said.

    Troubled by the presence of Carpophilus truncatus on his orchard in Hughson, Stanislaus County, Hicks said he recently partnered with Rijal to set some traps on his property, hoping to grow scientists’ understanding of the pest.

    “It takes growers to help advance that knowledge and be the ‘guinea pigs’ somewhat,” Hicks explained. “At the same time, if it helps us growers as a whole, that’s a good thing.”

    During his opening talk, Rijal reiterated the need for growers to clean up the remnant “mummy” nuts on the ground that serve as overwintering habitat and a food source for the next generation of beetles in the spring.

    “Do the sanitation so you can destroy the population from the beginning and you will have less of a problem,” said Rijal, who also shared a visual ID guide that can help growers identify the specific pest in their orchard and thus better target their control methods.

    Growers also heard practical advice on an emerging almond disease, red leaf blotch, caused by the fungus Polystigma amygdalinum. Named for the orange-red patches of discoloration on leaves, red leaf blotch in almond has led to significant crop loss across Mediterranean countries. Unknown in California prior to last year, there was an explosion of reports throughout the San Joaquin Valley during 2024.

    “It was pretty surprising, both the quickness and vastness of the spread,” said Alejandro Hernandez-Rosas, a UC Davis Ph.D. candidate in the lab of Florent Trouillas, UC Cooperative Extension specialist in the Department of Plant Pathology at UC Davis.

    During his presentation, Hernandez-Rosas said a preventative application of fungicide at petal fall – and then again at two and five weeks after petal fall – appear to work best to manage this disease. Fungicide applications made after the blotchy leaf symptoms appear will not be effective, Hernandez-Rosas said, and further research needs to be done to determine the most effective products and optimal timing for growers to make the most of their applications.

    And because leaf litter is the “primary source” of the disease inoculum, Hernandez-Rosas added that cultural practices focused on speeding cleanup or decomposition of leaf litter are critical to reduce disease severity. However, it is only effective if done over a wide area in conjunction with neighbors.

    Advanced symptoms of red leaf blotch (RLB) include large, yellow-orange blotches (roughly 1/2″) that turn reddish-brown in their center. Photo credit: Alejandro Hernandez and Florent Trouillas

    Rodents, irrigation, replanting and whole orchard recycling

    Both Arshad and Hicks mentioned that they intend to tackle the gopher problem in their orchards.

    “I plant a cover crop every year and the gophers tend to really like it – so I get overrun with those gophers,” Hicks explained. “I’m trying to find that balance of not letting them overtake my orchard but still being able to cover crop – because that’s beneficial too.”

    With many growers voicing a desire to learn about burrowing rodents, Almond Day organizers were pleased to schedule a presentation by Roger Baldwin, professor of Cooperative Extension in the Department of Wildlife, Fish and Conservation Biology at UC Davis.

    Baldwin presented the available control options for not only pocket gophers but also ground squirrels and meadow voles. He stressed the need to understand the biology and ecology of the rodents to maximize efficacy; for example, whereas ground squirrels prefer green foliage as their main food source in the spring, they switch to seeds in the summer/fall – which would thus be a better time to use pelletized baits.

    In choosing from baiting, trapping, habitat modification, burrow fumigation, biocontrols and other options, Baldwin recommended combining different strategies and approaches in an integrated way.

    “Mixing and matching tools will give you the best possible results,” he said.

    The utility of combining methods was also a key takeaway from the presentation by Moneim Mohamed, UCCE irrigation and soils advisor. Highlighting the latest tools and innovations, Mohamed outlined the soil-based, weather-based and plant-based methods to collect data that can help growers make the most of their water.

    Mohamed said using even just one approach is beneficial in optimizing irrigation scheduling – but more is even better. “A combination of the three methods is the best,” he said.

    Cameron Zuber, UCCE orchard crops farm advisor for Merced County, discussed considerations related to replanting an orchard, including field and soil conditions and the management of plant-parasitic nematodes and aggressive pathogens and pests. He also encouraged attendees to visit growingthevalleypodcast.com for more information on tree nuts and a host of other topics.

    Finally, Brent Holtz, UCCE orchard systems farm advisor for San Joaquin County and a trailblazer for whole orchard recycling, presented an overview of WOR. He then shared recent findings on its effects on fungal pathogens, and ways to mitigate drawbacks of WOR – such as the initial carbon-to-nitrogen imbalance when the recycled almond wood chips are first spread on a field.

    Hicks, who has already tried WOR in his orchard, is also the grower relations manager for RPAC, a Los Banos-based company that grows, processes and markets almonds. Hicks said he also brings what he learns during Almond Day to his fellow growers – illustrating the multiplier effect of such educational events.

    “I have growers who possibly will be doing whole orchard recycling, and I can share that information,” Hicks said.

    UC Agriculture and Natural Resources brings UC information and practices to all 58 California counties. Through research and Cooperative Extension in agriculture, natural resources, nutrition, economic and youth development, our mission is to improve the lives of all Californians. Learn more at ucanr.edu.

  • Got Carpophilus Beetle? Make it Official with Ag Commissioner

    The carpophilus beetle, a serious pest threatening California’s almond industry, is officially documented in only four counties — Stanislaus, Merced, Madera, and Kings. However, according to entomologists and industry experts, its presence is far more widespread, raising concerns about the limitations of official reporting and its impact on securing resources for control and mitigation.

    Houston Wilson, a Cooperative Extension specialist in the Department of Entomology at UC Riverside, has been surveying reports and conducting research on the beetle in collaboration with other UC and USDA researchers. “We’ve identified infested orchards — both almonds and pistachios — from every county within the San Joaquin Valley,” Wilson said. “We’re also hearing reports of crop damage from the Sacramento Valley (Sacramento through Butte County), but we have yet to directly confirm it there due to limited survey efforts.”

    The Importance of Official Documentation

    Despite mounting evidence of the carpophilus beetle’s spread, official state records remain limited. Wilson explains that for a find to be considered “official,” the county Agricultural Commissioner must collect a sample and submit it to the California Department of Food and Agriculture (CDFA) for verification. The current process means that many beetle infestations, though identified by researchers, remain unofficial.

    “While we have unofficial records from our survey efforts, my understanding is that the official records only reflect what has gone through the CDFA process,” Wilson said.

    For growers, the discrepancy between unofficial and official findings is more than just a technicality — it could also affect the allocation of resources. According to the Almond Alliance, securing state and federal assistance depends on having documented proof of the beetle’s widespread presence.

    “The widespread documentation of the carpophilus beetle serves as a vital indicator of the extent and severity of the issue,” said Almond Alliance CEO Alexi Rodriguez. “When more counties report official beetle findings, it underscores the pervasive nature of the problem, highlighting its impact beyond isolated areas.”

    Challenges in Reporting

    Wilson acknowledges that the reporting process can be complicated, but he and his team actively assist growers. “If a grower contacts me about suspected beetle damage, I usually visit the farm to assess the situation,” he said. “If we confirm the presence of the carpophilus beetle in a county that hasn’t had an official report, we advise them to contact their Agricultural Commissioner and guide them through the reporting process.”

    Rodriguez recognizes the difficulties growers face in reporting. “I want to acknowledge that the reporting process is not easy; however, expanding the network of official findings will allow us to advocate for more effective solutions by highlighting the problem’s regional and national significance,” she said.

    Identifying the Carpophilus Beetle

    For growers looking to detect the beetle, Wilson advises examining nuts in windrows, where nuts can be easily sampled. “The most apparent sign is a fine, powdery white frass on the nut, which results from beetle larvae tunneling into the kernel,” he said. “If you blow that frass away, you might see a circular hole in the shell where the adult beetle chewed through to lay its eggs. Inside, the larvae create distinctive oval-shaped tunnels in the kernel itself.”

    Wilson is part of a team that last year developed a pest identification guide to help growers differentiate carpophilus beetle damage from other pests, such as navel orangeworm or ants.

    Securing Support for Growers

    To address the growing concern, the Almond Alliance continues to work with officials at both the state and federal levels. “This engagement is expected to lead to more coordinated and robust interventions, mobilizing the necessary support and funding to mitigate the impact of beetle infestations on ecosystems, agriculture, and local economies,” Rodriguez said.

    Meanwhile, research efforts continue. “We’ve secured funding from the Almond Board of California and the California Pistachio Research Board for a second year, and we’ve now leveraged that into a larger pool of funding from the USDA,” Wilson said.

    Growers can also take advantage of upcoming pest identification workshops organized by the Almond Board of California in March, where they can learn more about identifying carpophilus beetle damage.

    A Call to Action

    With the evidence pointing to a much wider distribution of the carpophilus beetle than official records reflect, the push for more growers to report infestations is crucial. “If we don’t have official documentation, we can’t make the case for more resources,” Rodriguez emphasized. “We urge growers to work with their local Agricultural Commissioners to ensure the beetle’s spread is formally recognized.”

     

    By increasing official reports, the almond industry can strengthen its efforts to combat the carpophilus beetle, securing the necessary funding and support to protect California’s valuable almond crops. — By the Almond Board of California

  • 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

  • Congressman John Duarte Shares Legislative Priorities for California Ag in Crisis

    In November 2022, the newly realigned 13th Congressional District of California elected to send a farmer to represent them in congress. Representative John Duarte has been at the job for about a year in a half and has been working on a number of bills to support California’s specialty crop industries, which are in desperate need of recovery from many challenges brought on by the pandemic and drought, among other global trade, inflation, and invasive pest pressures. Watch his brief interview with Matthew Malcolm from California Ag Network to learn more.

    Please thank this video’s sponsor Southern California Gas Company for their industry support.

  • Sneak Preview of First Ever Pistachio Industry Insights Day Coming This Month

    It’s that time of the year as pistachio harvest nears that American Pistachio Growers (APG) gathers its members together at the Visalia Convention Center. But this year, growers are invited to more than just your typical Summer Luncheon. This longtime tradition has been reinvented into an all-day event to support the booming western pistachio industry. APG’s Wes Wilson met with Matthew Malcolm on California Ag Network to share a sneak preview of what growers can expect in attending the Pistachio Industry Insights Day. Watch this brief interview and be sure to come see Pacific Nut Producer Magazine there as a proud sponsor of this event.

  • What Nut Growers Can Do to Combat the New Carpophilus Pest

    It seems we are always on the verge of some type of apocalypse, and with the new carpophilus beetle invading California tree nut orchards, there is cause for concern.  Watch this brief California Ag Network interview with UC Riverside CE Entomology Specialist Houston Wilson to learn more about this pest and how to stop it from damaging your crops.

  • New Invasive Pest Threatens Western Tree Nut Industry

    Western tree nut commodities just got through a very tough season, and markets are still less than ideal.  The last thing growers want to hear about is a new pest threatening their orchard production.  But the Carpophilus Beetle has already been under the radar far too long, damaging Central Valley orchards under the guise of “Navel Orangeworm.”  Watch this brief video with Bob Klein from the California Pistachio Research Board as he explains, and read more about this new pest in the December and January issues of Pacific Nut Producer magazine.

    Please thank this video’s sponsor Thunder Creek Equipment for their industry support.