Pacific Nut Producer Magazine

Tag: California Pistachio Research Board

  • Researchers Requesting the Help of Pistachio Growers

    California pistachios now cover more than 600,000 acres and generate over $2.5 billion annually. As demand for pistachios continues to grow worldwide, production remains concentrated in the Central Valley with some acreage in coastal counties. However, a changing climate is creating new challenges for growers.

    Although the 2025–2026 winter felt “normal” with cold, foggy days, a closer look at the data shows that some pistachio orchards may not have received adequate winter chill. The March heatwave, which coincided with bloom, further intensified bloom and nut-set irregularities, issues many growers have already reported. However, some orchards were severely affected while others showed little or no impact, pointing to underlying factors that are not yet fully understood.

    This situation presents a valuable opportunity to better understand how unseasonable weather affects bloom, fertilization and set. To this end, the University of California, Davis (UCD) and the California Pistachio Research Board (CPRB) have developed a short grower survey. The information collected will help researchers evaluate the impacts of climate variability during this critical developmental stage. Several CPRB-funded research trials focused on improving yield and quality may also benefit from the survey data. These findings will help researchers develop strategies to prevent or mitigate similar impacts in the future and identify priority areas for targeted research. Grower participation is essential: the more orchards represented, the clearer the picture will be for guiding future research and management decisions.

    The California Pistachio Research Board encourages growers to complete the survey and share observations from their orchards this season. Growers with multiple orchards showing different performance under the same cultural practices (e.g. irrigation, fertilization) are welcome to submit separate responses for each site. The survey takes only a few minutes to

    complete but will provide valuable insights for future research.

    All responses are anonymous unless you choose to provide contact information. Growers can use the link or QR code below to access the survey.

    Pistachio Survey: https://forms.gle/vyeXgnoGfYG3aDDQ9

  • Smoke from Megafires Reduces Nut Crop Yields

    Long-term smoke exposure from massive wildfires lowers the energy reserves of orchard trees and can cut their nut production by half, researchers at the University of California, Davis, found. The smoke can affect trees for months after a megafire, depressing their bloom and the next season’s harvest. This finding reveals a new danger from wildfires that could affect plant health in both agricultural and natural environments.

    Nature Plants published the study on Oct. 2nd.

    “A lot of research focuses on the impact of smoke on humans but there is less study on the effects of smoke on plant health,” said lead author Jessica Orozco, a postdoctoral researcher with the UC Davis Department of Plant Sciences. “Our study suggests that trees are just as vulnerable as humans.”

    Wildfire smoke blocks sunlight

    Scientists studied almond, pistachio and walnut trees at 467 orchard sites in California’s Central Valley from 2018 to 2022. In 2020, megafires scorched more than 4.2 million acres in California, filling the skies with smoke and ash. At the time, researchers were studying how trees store energy, in the form of carbohydrates, to cope with heat and drought. But Orozco said the team saw an opportunity to study how smoke affects carbohydrate levels.

    “Photosynthesis produces carbohydrates, which are critical elements for tree survival,” said Orozco. “Trees need carbohydrates not just to grow but to store energy for when they’re under stress or when photosynthesis isn’t happening.”

    Photosynthesis changes under smoke-filled skies. Smoke particles block some sunlight but also reflect light, creating more diffused light. The diffused light can help trees make more carbohydrates. However, Orozco said the study found that while diffused light increased, the smoke was so thick that it likely didn’t compensate for the loss of direct light.

    Megafires have lingering effects on tree health

    The team found that megafire smoke not only reduced the amount of carbohydrates in trees but also caused losses that continued even after the fires were out. This led to nut yield decreases of 15% to as much as 50% in some orchards. The most active time for wildfires also coincides with the time trees start storing carbohydrates to sustain them through winter dormancy and spring growth.

    “We were expecting to see some impact especially in the months when the smoke was really dense, but we weren’t expecting the smoke to have such a lingering effect and result in a significant drop in yield,” Orozco said.

    Orozco said researchers still don’t know what components in megafire smoke caused the decrease in tree carbohydrates. During the 2020 megafires, the smoke reduced light and increased both ozone and particulate matter levels, all of which affect photosynthesis. One or a combination of these factors could have led to the drop in tree carbohydrates.

    Additional authors on the study are Professor Maciej A. Zwieniecki and postdoctoral researcher Paula Guzmán-Delgado of the UC Davis Department of Plant Sciences.

    The Almond Board of California, the California Pistachio Research Board, the California Walnut Board and the California Department of Food and Agriculture supported the research.

  • 5-Year Pistachio Crop Forecast Reveals Tremendous Growth

    At American Pistachio Growers annual Pistachio Industry Conference this year, Bob Klein, Manager of the California Pistachio Research Board, gave his final presentation before retiring with a five-year California pistachio crop-yield forecast.  The numbers were stunning with the tremendous growth of the industry and pistachio acreage expected to begin bearing. Pacific Nut Producer Editor Matthew Malcolm met with Bob to better understand the analytics and what the industry can expect for 2024 and beyond. Watch this brief interview and read more about it in the May issue of Pacific Nut Producer Magazine.

  • 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.

  • IKD Concern for Golden Hills Pistachio Variety

    Internal Kernel Discoloration (IKD) is a recent cosmetic concern discovered in the Golden and Lost Hills varieties of pistachios, which now make up about half of the total planted acreage of California pistachios.  While IKD is only noticeable inside the kernel and does not alter the flavor of the nut and is of no food safety concern, USDA Specialty Crops Inspection has indicated that they intend to consider this as a defect under the voluntary USDA Grades and Standards for pistachios and would score it as “damage”.  The industry strongly disagrees with USDA on this as it would cause unnecessary and costly problems should they choose to move forward with this.  Watch this brief interview with Bob Klein from the California Pistachio Research Board to learn more.

    Please thank this video’s sponsor G3 Enterprises for their industry support.

  • Are Tree Nut Growers Doing Their Part to Manage Navel Orangeworm?

    Winter sanitation, mating disruption and proper pesticide application — all critical strategies in managing the number one pest of tree nuts: Navel Orangeworm. No one wants this pest on their farms, but are growers really doing their due diligence in managing this pest with tools that are now widely available to the industry?  Watch this interview with Bob Klein from the California Pistachio Research Board as he shares the rough statistics and read about how you can do better in Pacific Nut Producer Magazine.

  • California Pistachio Crop Projections for 2020 Season

    With more and more acreage of pistachios coming into production, California growers anticipate the largest crop ever this year.  Watch this brief video with the Bob Klein from the California Pistachio Research Board as he shares his thoughts on pistachio chill accumulation this winter, acreage trends and water supply levels that should lead to their largest harvest yet this year.  Read more about it in Pacific Nut Producer Magazine.

     

    Please thank our sponsor Duarte Nursery for their industry support and see them at their booth at the APG Conference in Monterey, March 2-4 (Booths 20-21).

  • Sterile Insect Facility to Aid Growers with Navel Orangeworm Management

    Researchers and growers are tackling the formidable tree nut pest Navel Orangeworm from all fronts.  One method underway is in utilizing the same sterile insect technology and facility that eradicated pink bollworm from the cotton industry years ago.  There have been some challenges in adapting the system for Navel Orangeworm, as shared by Bob Klein from the Pistachio Research Board; however there is great potential for this program to aid growers in managing this pest.  Watch this brief interview with Bob and read more about it in Pacific Nut Producer Magazine.