Adequate pistachio chilling expected

Chilling hours for pistachios continue to accumulate, according to Craig Kallsen, UC Cooperative Extension Kern County Farm Advisor.

“Chilling hours are commonly calculated by adding hours less than 45 degrees from Nov. 1 through Feb. 28,” he says. “This season, it looks like we’ll have more than enough chilling in most areas of the San Joaquin Valley. In some areas, we already have over 1,000 hours, and most areas will be near or exceed 1,000 hours by Feb. 28.”

That bodes well for the spring. “If we can accumulate over 800 hours, we usually have a very good bloom,” Kallsen says.

Research on pistachio cultivars continues, with the goal of mitigating the impact of alternate bearing years.

“So far, the University of California pistachio breeding program has released two new female varieties and one new male variety to growers — all in 2005,” Kallsen says. They are the female cultivars “Golden Hills” and “Lost Hills”, and the pollinating male “Randy”.

“The main advantage of the female varieties is that they are harvestable approximately two weeks earlier than Kerman,” Kallsen says. “We continue to evaluate other pistachio genotypes and selections.” The first commercial production of the new varieties is expected this fall.

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