California Pistachios: Free Online Tool Helps Predict Yields

    Photo: Fresno State University

    Fresno State researchers created an online pistachio harvest predictor to assist San Joaquin Valley growers in predicting yields for one of the area’s most popular crops.

    The free website will help growers with their harvest, market and budget planning. It was created by Shawn Ashkan, a Center for Irrigation Technology research agricultural engineer, and Dr. Gurreet Brar, a Fresno State plant science faculty member.

    To get a predicted yield, website users are asked to enter recent chill portion totals from their orchards’ nearest or representative California Irrigation Management Information System (CIMIS) station, the previous year’s per acre yield and information on whether the predicted year is a normally higher or lower year in its naturally alternating cycle.

    “Pistachio farmers haven’t had any highly-developed, predictive tools like this, so we wanted to create an easy-to-use site that can apply to orchards of all sizes and different locations,” Ashkan said. “The best part is its dynamic machine learning model that gets more accurate as people enter more and more data that sharpens the predictive algorithms, just like in our own personal lives when we use Microsoft, Google and Amazon.”

    The dynamic model’s chill portion units are based on time and temperatures that the orchard experiences in its dormant stages from early October through mid-March. More emphasis is placed on temperatures in the 35- to 55-degree range, but the model accounts for temperature fluctuations as well.

    To build the website, Ashkan and a Fresno State student assistant inputted weather station data from 25 CIMIS stations from Bakersfield to Merced.

    They also collected harvest data from area growers with help from Brar and University of California Extension farm advisers Phoebe Gordon (Madera) and Mae Culumber (Fresno), and they tied the data to nearby CIMIS stations. Additional information was added from 22 years of county commissioner growers’ data dating back to 1996.

    Ashkan also partnered with Dr. Mark Keith, Brigham Young University associate professor of information systems, to design the website and its analytical model formulas.

    The project was funded by a specialty crop block program grant from the California Department of Food and Agriculture. Ashkan did background investigation on a grant proposal in 2015 with Brar, who was then a UC Extension advisor, then submitted a final proposal when Brar returned from a one-year stint at the University of Florida to accept the University’s Rodger B. Jensen Professorship in Pistachio Physiology and Pomology.

    “Pistachios are one of our most chill-dependent orchard crops, so this is a vital tool,” Brar said. “As we see our winter climate fluctuate more, the dynamic model continues to adjust, which is really important based on the crop’s dormancy sensitivity. This calculator is a perfect example of how our University can work with researchers, extension agencies and industry to lead agriculture in new directions, and one of the reasons why I came back to the Central Valley.”

    California has over 312,000 acres of pistachio orchards that account for 99 percent of the domestic pistachio supply. The San Joaquin Valley is the state’s leading production area of the crop that was first grown commercially in the United States in 1976. Growers accounted for a record 900-million-pound harvest nationally in 2016.

    For more information, contact Ashkan 559.278.8652 or

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