Almond Blooms
Credit: USDA
February 14, 2018 - By Kevin Hecteman - In the weeks leading up to mid-February, California farmers went from sweater weather to sweating the weather, with unseasonably warm temperatures and a near-total lack of rain and snow leading to cherry-crop worries and discussions of renewed drought.
"We have this upper-level ridge pattern, which has been blocking a lot of the storms from the West Coast—really shifting them up more into the British Columbia area, and somewhat to the Pacific Northwest," said Eric Kurth, a forecaster with the National Weather Service in Sacramento.
This ridge, reminiscent of the "ridiculously resilient ridge" that parked itself over the West Coast during the winter of 2013-14, pushed temperatures around Northern California into the 70s last week—levels usually not seen until April or May, according to the National Weather Service.
All that warmth could take a bite out of California's 2018 cherry crop.
Joe Grant, University of California Cooperative Extension emeritus farm advisor in Stockton, said most cherry varieties need 850 to 1,000 chilling hours during the winter; so far, the Stockton/Modesto area has had about 700 hours, he said. Chilling hours are periods where the temperature drops below 45 degrees, and the meter starts running around Nov. 1; in an average year, Stockton and Modesto would have had 900 to 1,100 hours, he added.
"Cherry trees, among tree crops, have one of the highest chilling requirements," Grant said. "All trees need a certain amount of cold exposure in the wintertime. It's an adaptive thing that they evolved with. They need to go dormant in the winter."
Grant emphasized that chilling hours aren't the only or best measure of chilling, primarily because they don't account for the "subtractive" effects of intermittent warm daytime temperatures.
"What happens is, as soon as the weather starts to warm up, like it is now, the tree starts to grow again, regardless of how much chilling it has," he said.
Ken Vogel, who grows cherries and walnuts in Linden, said he's trying to encourage his cherry trees to bloom uniformly—that is, to have all the trees bloom within a few days of each other.
"Uniformity is important," Vogel said. "The lack of cooling hours affects that.
"The other thing that might affect us—cherry growers, sometimes we're our worst enemies," Vogel added. "We want a crop earlier, but then we get into problems when it is early. If it comes too early now with this heat, it could bring us into a situation where if we get rain—which we do want—when it's raining during bloom, that's hard for pollination."
As bloom goes, so goes the season, Grant said, noting that in a year such as this, the bloom can be "very straggly."
If a bloom is spread out over 10 or 12 days instead of four or five, "you get a very straggly harvest period"—picking crews may have to make their way through the orchard two or three times instead of only once, he added.
"It really increases the harvest hassles and the harvest costs," Grant said.
Growers also have crop-treatment schedules to consider, he said. Farmers normally apply fungicides at bloom time and insecticides sometime thereafter, with the timing depending on crop development.
"When you have an all-straggly bloom, it's hard to get good impact from these sprays," because crop development is staggered, Grant said. "It's a real problem in terms of growers having the most efficient harvest and the best impact from these cultural practices."
Then there's the issue of water.
The Sierra snowpack statewide stood at only 21 percent of average as of Monday. Although reservoir storage generally looks OK, thanks mainly to last winter's deluge, observers said farmers have good reason to be concerned about water supplies.
The time for farmers to make planting decisions has arguably passed, said Ryan Jacobsen, executive director of the Fresno County Farm Bureau.
"All they can essentially bank on at this point is (water) they may have carried over from the previous year, but knowing there is probably at this time not going to be a whole lot of water available above and beyond that," Jacobsen said.
He said he's not exactly expecting good news from the U.S. Bureau of Reclamation, which will announce initial water allocations for Central Valley Project agricultural customers later this month. Last year, western Fresno County farmers received 100 percent from the CVP, the first full supply from the project since 2006.
"We could probably be anywhere between 20 and 40 percent this year, just based off of the carryover from last year, but until that number's known, it makes it very difficult to plan for anything but a worst-case scenario," Jacobsen said, adding that "it's going to take some significant storms to even get us remotely in better shape than what we are at this time."
It's a toss-up as to whether those storms will show up. Kurth, the NWS forecaster, said this year's pattern is following the La Niña template: wetter than usual up north; drier than usual down south; could go either way in between.
The paucity of rain so far has prompted Vogel to irrigate his orchards once already, in late December and early January.
"If this continues, we're going to have to irrigate again," he said. "That's an extra expense."
Last year, he didn't start irrigating till May, he added.
"You don't want your trees to come alive from dormancy and have the roots dry," Vogel said. "Cherries are more shallow-rooted than walnuts, so you want to be sure the cherries have moisture."
Vogel relies on wells to irrigate his trees.
"This year, it looks like we are going to be irrigating sooner, and even if you have the deep wells, it still draws the level down and costs more money," he said.
Where things go from here is largely out of farmers' hands, Jacobsen said.
"Essentially," he said, "wait for Mother Nature to show us what she's got for the rest of the season, and continue to balance and make your plans from that point."
(Kevin Hecteman is an assistant editor of Ag Alert. He may be contacted at khecteman@cfbf.com.)
Reprinted with permission: California Farm Bureau Federation
