Lower chill hours, drought substantially reduce California pistachio yields

Lower chill hours, drought substantially reduce California pistachio yields

“I’m not sure how much more will come in, but everyone’s guess is that the total U.S. crop will not exceed 275 million pounds,” said Richard Matoian, executive director of the American Pistachio Growers in Fresno.

A chill spreading through California’s pistachio industry caused by a lack of chilling hours last winter appears to have cut yields by hundreds of thousands of pounds tied to high numbers of blanks.

As September closed, California crop receipts were pegged at just over 262.7 million pounds, according to a memo issued by the California Pistachio Research Board. This is well below last year’s 520 million pound crop.

In all, U.S. production by Sept. 30 was just over 267 million pounds.

“I’m not sure how much more will come in, but everyone’s guess is that the total U.S. crop will not exceed 275 million pounds,” said Richard Matoian, executive director of the American Pistachio Growers in Fresno.

He said, “This is a very disappointing year indeed.”

The smallest California crop in the past decade was 237.5 million pounds in 2006.

Last year’s crop came out of an ‘on’ year for the alternate bearing crop that is commonly marked by heavier crops following lighter ones. But there had been an expectation that this year’s crop might match last year’s.

Matoian says those hopes were dashed by two issues.

“There was a lack of chill hours during the winter which contributed to uneven bloom,” he said. “Male trees came out at different times than females, and there was not an even pollination.”

This was in addition to the fourth year of a drought.

Some 800 hours of temperatures below 45 degrees are needed to set a good crop. In some instances, Matoian said, hours of below 45 degree temperatures were negated because they were followed by warm, sunny days.

Kern County farming consultant Carl Fanucchi said the lack of chilling was particularly acute in the southern San Joaquin Valley.

“We did not even get one day of fog this year,” Fanucchi said. “We had weather stations report only 424 hours, and that doesn’t count for anything. Some reported the lowest totals ever.”

“The blanks are horrible,” he said. “Normal blanking is 4 percent to 5 percent. This year, there’s nobody below 12 percent, and the average is closer to 30 percent.”

Some orchards are harvesting as low as 200 pounds per acre when blanks are removed, he said.

Mature trees can produce 3,000-4,000 pounds in a good year. 

“A lot are harvesting at less than 500 pounds per acre,” Fanucchi said.

To cope with the lack of chilling, some growers have been relying on an oil for worm and scale control that helps enhance dormancy. But Fanucchi said that approach has not been as effective during two years of back-to-back low chilling, and some are wondering if there is an accumulative effect from the extended lack of chill.

Tulare County grower Brian Watte said some of his neighbors are “doing tests by applying a product in the fall” that is believed to keep branches cooler by a few degrees. But it is not known if that is effective.

Watte said blanks were not a big problem on his ranch, but his crop was just a fourth of normal, coming in at about 1,000 pounds were acre, due to the lack of chilling. He had adequate water and “there were no bug issues.”

Bob Beede, University of California farm advisor emeritus for Kings County, discovered in the early 1900s that the dormant mineral oil used for pests for decades also proved useful in countering the effects of lower chill hours until the “widely erratic winter temperatures of the past two years.”

He speculated that could be because in both years there were unusually warm temperatures in January, which he said is one of the two most important chill months. The other is December.

“The warmer days and the absence of fog raised bud temperatures and that appears to have resulted in severe negation of winter rest and consumption of stored carbohydrates in fruit wood because of a higher rate of respiration,” Beede said.

“That opinion has not yet been substantiated,” he said.

Beede expects researchers will be looking further into the chilling challenge, which he said has significant impacts, particularly for growers of pistachios and walnuts.

“We desperately need for chilling hours to return for nut and other agricultural crops that depend on cold winters and to destroy pests,” Beede said.

Among those looking at the challenge, Beede said, is David Doll, UC farm advisor in Merced County. He has been studying if use of multiple applications of a sunburn protectant that whitens the tree may help address the problem.

Growers say the effects of chilling were variable, depending on the region.

“It’s a tale of two cities geographically,” said Kevin Herman, who grows pistachios in Madera and Merced Counties. He said areas that appear to have been hit particularly hard are on the valley’s west side and to the south, where there are historically warmer climates.

“Most of those folks are not happy campers. From Fresno County northward and on the east side, people are doing OK compared to the other guys.”

Herman believes prices will remain stable, but he expects some resistance as growers try to get still higher prices, considering “prices have been going up about 50 cents every year for the past four years.”

“We may have found the ceiling,” he said, speculating that prices will be in the range of $3.75 per pound.

Pointing to recent positive years for the industry, Fanucchi said, “We’re bound to have our lumps mixed in with all the good we have. Everybody wants to plant new acres, but I tell them, ‘Don’t be greedy.’ With all the groundwater regulations coming in, it’s time to hold on to the ground for the water. We’re in the third year of deficit irrigation.”

He said there are probably 100,000 acres of non-bearing pistachios trees.

A bit of good news is that “the carryover from last year was pretty large,” said Chuck Nichols, who grows pistachios in Kings, Tulare and Fresno counties. Another positive note, he added, is that the quality of the crop is good and that there appeared to be less pressure from Navel orangeworm.

Nut size is small, Nichols said, adding that the harvest began early this year.
He expected the crop to be 30 percent to 45 percent of what it was last year, but the carryover will mean that supply will only be down about 20 percent.

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