Good pistachio bloom winds down

Good pistachio bloom winds down

Central San Joaquin Valley PCA Zack Raven reports it has been a “good bloom” in the southern reaches of the valley with nuts already BB size.

The pistachio bloom across northern Kings County and points south in the San Joaquin Valley has run its course, reports PCA Zack Raven, grower service manager for Keenan Farms, Avenal, Calif.

He works with other growers as far north as Madera County, where, he estimates, 70 percent or more of the trees had finished blooming.

“It’s been a good bloom and now a lot of the nuts are the size of BBs,” he says. “In a few cases, some of the male trees started blooming earlier and some later than the females. But, the overlap should be sufficient for a successful fruit set. Some growers self-pollinated trees by using airplanes or blowers to spread pollen over their orchards.”

Growers who treated orchards with a dormant oil, typically in early February, saw their trees blooming about 10 to 14 days earlier than those who didn’t use oil.

Recorded winter chilling hours seemed to be enough for the trees. However, Raven notes, a modest mistiming between the males and females is raising doubts whether chilling was sufficient. Regardless, by speeding up the start of the season, the dormant oil treatment puts those growers in better position for timely harvesting once the nuts mature.

“With continued warm weather into early summer, harvest could begin around the first of September on Kerman and around mid-August on Hill varieties,” Raven says. “That’s about the normal time. It would be at least a week earlier than last year.”


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Now, however, it is the shortage of surface water for irrigating this year’s crop that is a big concern. Surface water allocations are only 20 percent of contract this year, the lowest in four seasons.

With declining water tables, some growers will dig wells deeper than ever to make up for the shortfall in surface water. “I’ve heard of one grower who had to drill 2,300 feet to get water,” Raven says.

However, there’s an upside to the mostly dry weather this year. With little moisture to trigger development of fungal diseases, alternaria and botrysphaeria have posed few, if any, problems for his growers, he notes.   

At the same, though, the overwintering navel orangeworm (NOW) have “enjoyed” the dry winter. That’s especially worrisome, following the flare-up in NOW populations late last season. In fact, it prompted some growers to interrupt their harvest to treat orchards with an insecticide.

The extent of any NOW threat this season depends to a large degree on how well growers practiced winter sanitation. That involves shaking mummies off trees, shredding prunings and disking in the mummies.

Raven, though, is encouraged. “Growers are paying more attention to the navel orangeworm problem and are taking more action to keep their fields clean,” he says.

This report is from Tree Nut Farm Press, a twice-monthly electronic newsletter published by Western Farm Press during the growing season. This edition was sponsored by Valent USA.  If would like to receive Tree Nut Farm Press go to the Western Farm Press home page ( and sign up for it and other Farm Press electronic newsletters.

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