Legendary “mother” pistachio tree to be retired
 Always a curiosity to Kearney visitors is an extra large pistachio tree growing within a huge wooden frame. In the spring, the scaffolding in this frame supports a plastic cover that allows this “mother tree” to be hand-pollinated.
It was planted as part of a variety block of pistachios at KREC by now-retired UC Cooperative Extension pomologist Carl Optiz. The female parent tree, Pistacia atlantica, was crossed in 1980 with a male Pistacia integerrima in the same block by Lee Ashworth in the UC Berkeley Department of Plant Pathology.
The resulting rootstock produces the highest yields of any pistachio rootstock in California and has an optimal combination of tolerance to cold, salinity and Verticillium wilt. “This means the California pistachio industry can be extended into areas previously thought too cold for other rootstocks,” says Cooperative Extension pomologist Louise Ferguson. “More importantly, trees can be planted in soils not suitable for any other fruit or nut tree in California, except dates, and irrigated with sub-par water quality.
This rootstock is now in extensive use in the lower west side of the Central Valley. Because the Foundation Plant Materials Service produces seed of this cross and budwood has been propagated by private source, Kearney’s will be retired later this year and the scaffolding removed.
“But, like a good mother,” Ferguson says, “she’ll always be there.”
— John Stumbos
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