Steve Van Duyn looked around an almond orchard he manages southeast of Galt on a chilly morning, surveying the effects of California's weeklong run of freezing weather. Several nights with temperatures dropping below freezing have Van Duyn and other growers concerned about their crops. "We've sustained some damage," he said. "The full extent, we won't know for quite some time. In a few weeks, we'll know—we'll have a better guess—but we really won't know till harvest time." Van Duyn said he'd been irrigating orchards each morning, to help warm the blossoming trees as much as possible. The deep freeze that struck the Sacramento and San Joaquin valleys had many growers pulling all-nighters, trying to save their crops. "It was unprecedented for just a number of years, as long as I can remember, that we were up every night, Monday through Friday night," said Ripon-based almond farmer David Phippen. Mel Machado, director of member relations for the Blue Diamond Growers almond marketing cooperative, said reports from Glenn to Kern counties showed temperatures as low as the mid-20s, with many areas dropping to 31 to 33. Though Machado and others can put numbers on the temperatures, they can't do the same to the 2018 almond crop just yet. "Long story short, I can't walk into my brother's marketing office and say, 'Here's what the crop's going to be,'" Phippen said. Reports of damage vary widely. "Because of the stage of (bloom) development, because of whether you have water or not to apply, we will see fields that are virtually untouched adjacent to ones that are severely damaged," Machado said. "It's going to be that variable, and it's going to make it that much more difficult to really figure it out." California farmers harvested 2.1 billion pounds of almonds on 940,000 bearing acres during the 2016-17 season, according to the Almond Board of California. The objective forecast for 2017-18 calls for close to 2.3 billion pounds. The cold snap resulted from a shift in the weather pattern, said Jeff Barlow, a meteorologist in the Hanford office of the National Weather Service, who said weather systems had been "coming out of the Gulf of Alaska and dropping south across the Pacific Northwest and sliding into Northern California, and then coming across the Central California interior." At the orchard Van Duyn manages near Galt—one of the almond, walnut and winegrape operations he oversees in San Joaquin and Stanislaus counties—he said the third-leaf Independence trees produce 400-500 pounds per acre in a good year. "So if we come in with a crop of between 400-500, I'd say we had negligible damage," Van Duyn said. "If we come in at 200-250, I'd say we had a 50 percent crop reduction." Van Duyn found damaged blossoms in the orchard, but also found many that survived the freeze intact. "Every morning, we're up here running the water from about anywhere from 10 o'clock at night to 2 in the morning starts, and running them all the way till 9 o'clock, 9:30 before it warms up," Van Duyn said. That water is a crucial factor, said David Doll, a University of California Cooperative Extension farm advisor in Merced County. "Most farmers rely on the use of water applications at a rate of 30 gallons per acre per minute," Doll said. "This will warm the orchard by 2-3 degrees, depending on the dew point and temperature. Farmers can also use wind machines, but this isn't as common" in almonds, he added. Phippen said he's seen no crop damage so far around Ripon and Manteca, but orchards near Oakdale and Waterford weren't as fortunate. One 20-acre parcel owned and farmed by his son-in-law suffered severe damage, he said. Phippen added that he's guardedly optimistic about his crop, thanks in large part to the warm weather that set off the bloom earlier than usual. "We've never had this much frost, so that would tell you this isn't stellar," he said, "but the bloom has been one of the nicest blooms I've ever seen. There's been a long dwell on the bloom. The concurrent pollination from one variety to the other has overlapped beautifully. We've had a lot of bee flight hours. There's not a lot to be said negative about the bloom period that we've had. It's just that we had this frost along with it." Phippen said he thinks he'll know by the first of May how the harvest will shape up. An almond tree's vulnerability to frost will depend on a number of factors, Doll said. "As the tree progresses through bloom and into nut development, it becomes more sensitive to frost conditions," Doll said. "For example, the critical temperature at pink bud (beginning of bloom) is 25 degrees; at full bloom, it is 26 degrees; and at nutlet stage, it is 28 degrees. Extended periods at or below this temperature (greater than 30 minutes) will lead to crop loss." Citrus growers in the southern San Joaquin Valley used wind machines and irrigation to fight the chill, according to California Citrus Mutual. With nearly half of this season's crop already harvested, growers were aiming to protect next year's crop, as the warmer temperatures earlier in the month caused the bloom to arrive early. "The coming days will reveal if damage was incurred," Citrus Mutual said. "Growers are optimistic that if there is damage, the trees will have ample time to bounce back and push out another set of blooms this spring." Warmer temperatures could reach the Central Valley this week, Barlow said, as two weather systems reach California. Source - http://agalert.com