Are Growers Adjusting Pistachio Pollination Methods in Response to California Climate Change?

Oct 31, 2023 | Pistachios, Pollination


A silent but relentless transformation is underway as the golden sun beats down on California’s pistachio orchards. The intricate dance between nature and agriculture in the Golden State has long been the envy of the world. However, with rising temperatures, prolonged droughts, and unpredictable weather patterns becoming the new norm, California’s pistachio orchards find themselves in a battle against the devastating impact of climate change. 

Central Valley pistachio growers in California are learning to adjust their pistachio pollination methods to combat these shifts and examine innovative solutions to diminish the impact of changing weather patterns on pistachio tree blossoms.

The Importance of Pistachio Pollination

Like many other nut-bearing trees, pistachio trees require successful pollination to yield a bountiful harvest. Pistachio trees are dioecious, meaning that individual trees are either male or female. Male trees produce pollen, while female trees bear the fruit (pistachio nuts). While Mother Nature excels at pistachio tree pollination, a bit of assistance can dramatically enhance the process.

Traditionally, this process has been facilitated primarily by wind pollination. However, temperature fluctuations and erratic weather patterns make relying solely on natural wind pollination challenging for growers.

Climate Change and Pistachio Tree Blossom

Rising temperatures, droughts, and unpredictable weather patterns in California lead to “bloom desynchronization,” which means that pistachio male and female trees may no longer bloom at the same time. Low chill hours, the number of chilling hours accumulated between 32°F and 45°F during winter, affect pistachio tree blossom timing. This mismatch in flowering times can lead to poor fruit sets and lower production, affecting the growers’ bottom line.

Climate Experts Weigh In

Leading climate experts in California are studying the impact of climate change on agriculture and have provided valuable insights into the challenges facing pistachio growers and other farmers. 

Dr. Tapan Pathak, a specialist in climate adaptation at the University of California, explains, “Part of my work is focused on quantifying the impacts of climate change on agriculture. This is important because once we know what we are facing, then we know how to create solutions…we have 400 crops in California, and each crop responds to climate differently. When we think about adaptation, we need to think about crop-specific and region-specific solutions.”

Louise Ferguson, a UC Davis plant physiologist, observes that climate change is leading to more erratic seasons and temperature patterns, which may threaten the viability of certain crops.

The graph displays the yearly accumulation of chill hours using weather station data for specific geographical areas in central California. Chill hours represent the total count of winter hours, with temperatures falling within the range of 32°F to 45°F.

Adapting to Climate Change

To combat the effects of climate change on pistachio tree blossoms and improve yield, growers are adopting several strategies to ensure successful pistachio pollination:

1. Shifting to More Resilient Varieties

Farmers selectively breed crops for heat, disease, and drought tolerance in response to the warming climate. For example, UC Davis researchers are working to make California’s walnut, pistachio, and stone fruit orchards more resilient. By selectively breeding for these traits, they aim to develop crop varieties that can thrive in the face of changing climate conditions, ensuring the sustainability of these key crops in California.

2. “Spray and Pray” Method

The “spray and pray method” of pollinating pistachio trees, a conventional but imprecise approach, involves collecting pollen and spraying it on trees with modified backpack blowers. This method has limited success since the grower lacks control over pollen distribution, and the application is vulnerable to wind interference, timing, and access to the orchard. 

According to Materra Farming farm manager Marc Capetillo, We have a lot of male trees out there and have a lot of pollen flying around, but sometimes, if the wind blows away from where we need it to, it doesn’t help us.”  

3. Pistachio Pollination With Technology 

Using cutting-edge technology, Edete’s precision pollination addresses the unpredictability of climate change on pistachio tree bloom and bloom desynchronization. This technology uses an autonomous pollinator, a tow-behind implement that precisely delivers pure and viable pollen to the pistachio tree canopy in a “fog-like” consistency, ensuring efficient and precise pollination even when natural conditions are unfavorable.

In a recent article, Meital Shaked, Vice President of Engineering at Edete, explains, “It is crucial that the maximum amount of pollen possible reaches its intended destination – the flower stigma…In mechanical pollination, the production of pollen from male trees is carried out separately, just when the pollen release is at its peak.”

Edete solves the pollination dilemma by bringing the right amount of pollen at the right time, regardless of the wind speed and/or direction, and delivering it directly to the female trees. Growers have seen pistachio yield increases between 15% and 30% when using Edete’s mechanical pollination technology.


Climate change is undeniably affecting the pistachio industry in California, particularly in the critical phase of pistachio tree blossom and pollination. However, combining innovative solutions, such as Edete’s precision pollination technology and adaptive practices by growers, provides hope for the industry’s future. 

By adapting to the unpredictability of climate change, pistachio growers are finding ways to increase yields, maintain consistency in production, and secure the long-term sustainability of this crucial agricultural sector. In the face of climate change, California growers work diligently to preserve their pistachio orchards and ensure a more resilient and prosperous future for the entire industry.

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Bland, Alastair. “Mangoes and Agave in the Central Valley: California Farmers Try New Crops to Cope with Climate Change.” CalMatters, 9 May 2023,

Lucas, Becca. “Partner Profile: Dr. Tapan Pathak, Climate Adaptation Specialist.” Sierra Nevada Research Institute, 7 Aug. 2020, 

Watson, E. “Edete offers high-tech alternative to spray and pray approach for artificial pollination.” AgFunderNews. (2023, April 23), 

“Winter Chill” (2023) Available at: 

Zane, Nadia. “The Importance of Chill Hours for Fruit Trees.” ANR Blogs, 14 Jan. 2015, 

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