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Extremely cold weather is in the forecast as we wrap up this week’s issue. Lows into the 20s are predicted early in the week. Forecast models vary, but some models show a chance for temperatures to fall into the mid to low 20s in the Sacramento Valley and into the northern San Joaquin Valley.


In our Links section connect with a white paper on frost prevention. Joe Connell, Farm Advisor Emeritus in Butte County, prepared the piece a few years ago and two of our contacts this week suggested that we make it available.


Bloom continues, although it did slow in places over the last week when temperatures dropped a bit after unseasonably warm conditions earlier. One estimate was that bloom was progressing in Nonpareils at about 10% per day but then slowed to 5% a day as conditions cooled.


Fungicide applications are on hold in certain cases. With a lack of rain or even dew, many growers haven’t been in a hurry to make applications. Some treatments may be delayed where producers are running water to mitigate frost/freeze damage. And as one of our contacts noted, a few farmers may hold back on fungicides until they see how much damage the crop sustains if frigid weather does develop.


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Chris Morgner, PCA, Agri-Valley Consulting, Merced

Bloom has progressed, but it slowed somewhat this week as the weather began cooling a little. In last week’s report, people mentioned the prospects for a flash bloom, but I’m not seeing that, although this weekend and next week we should have some really pretty blooms.


“The Butte-Padres are still coming into bloom. Nonpareils and their pollinizers are well along in bloom, and next week they will be in full bloom on a wide basis, I think. p>


“The big news this morning (2/16) has been the forecast for really cold temperatures next week, and that looks very dismal in terms of almonds. One private weather service I follow says we could have low temperatures down to 23 to 24 starting on Monday and into the week.


“I’ve never experienced those kinds of temperatures during bloom, and everyone hopes that won’t materialize. Maybe by the time this report goes out the forecast will look better. But right now, the models show 2 shots of dry, cold air – first from Canada, then a similar shot later in the week from Alaska.


“With Nonpareils, you start seeing injury at 27 degrees, based on one table. The more temperatures drop from 27, the more damage you can expect.


“A couple of my growers have applied fungicides, I think. In one case, the grower’s trees were a little early on bloom, and he expected to start treating early this week. Otherwise, it’s been very quiet. Nobody wants to do anything, which is understandable, considering how dry it’s been. We still haven’t seen any rain, and any wetness on the windshield in the morning is gone by 9 a.m. So, we haven’t had conditions that would trigger fungicide applications.


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“A lot of people were planning to start next week, and the recs have already been written. We told all of our clients to make one spray at full bloom. But those plans are changing in light of the weather forecast. Where growers were going to start running water for frost prevention, they won’t be able to get in the field by ground and nobody will fly on a fungicide at this point with so little disease potential.


“And with this sharp drop in temperatures, growers will likely hold off to see how that affects the crop. No forecast is guaranteed, but the service I follow states that the potential is there for lows in the low 20s. We’ll see.”


John Moore, PCA, Growers Crop Consulting, Bakersfield

Bloom varies widely this week, depending on where you’re looking in the county. It’s a little more advanced on the east side but not quite that far along on the west side or what you might consider the middle of the valley, like around Shafter and Wasco.


“I kind of pegged full bloom on the east side in Nonpareils on February 15. Buttes on the east side, though, are barely beginning to show a few flowers, so they would be at the pink bud stage (as of 2/16). In the center of the valley I can find orchards that are in full bloom by now.


“Bloom seemed to really happen fast. So far, I haven’t seen any strong petal fall. I’m kind of surprised that bloom is moving along as quickly as it is because temperatures got somewhat cooler this week compared to those warmer conditions earlier.


“I’m seeing differences in bloom, depending on whether people made a dormant spray. The university leans toward not doing one. Oil is expensive, of course, and several of my growers didn’t make the applications. But where they did spray, trees are much closer to full bloom.


“When I drive by my client’s fields, I can tell which did or didn’t get oil. The fields without dormant sprays seem to have more blooms open on the lower part of the tree and less on the upper portion. But fields that received a strong rate of oil seem to have a more even bloom and are ahead of where applications weren’t made.


“I have growers who automatically do an early bloom spray and those were made at pink bud. Everyone else talked a little about an application. That was maybe a week ago when we had some potential for rain, maybe slipping over the hills from Santa Barbara into the southern part of the valley. But if any rain fell, it would have been minimal, and those sprays never happened.”


Brian Gogue, PCA, Helena Chemical Co., Hanford

We’re looking at potential for frost on Monday and Tuesday (2/19-20), and the last forecast I saw showed the low at 29 both mornings. So, a lot of people are now (2/16) talking about getting the water going (for frost prevention).


“I haven’t seen a low of 29 in a few years, and we haven’t had significant frost damage in any of our almonds in probably 6 to 8 years. The highs will be around 55, based on the last forecast I saw, so it won’t be warm.


“It’s been cool enough this week to slow bloom in most cases. This has been kind of an odd bloom – both inside some orchards and from one ranch to the next. I was on one ranch today (2/16) where most of the ground is heavier, and bloom in younger trees was at 10% to 15% and maybe 30% on some of the younger trees. Three miles away bloom ran 80% to 90% in a part of the ranch with lighter soils along the Kings River.”


“A few fungicide applications went on last week. Out west where we usually don’t have issues I did not include a fungicide. But in certain areas where it’s typically wet – back toward Hanford and around Lemoore – I did include a fungicide in the early bloom sprays. I plan on starting some full-bloom sprays Sunday night. I typically go with a fungicide at full bloom, regardless of the forecast.”


Franz Niederholzer, UC Farm Advisor, Sutter/Yuba Counties

In the Yuba City area, almonds look pretty much like they’re in full bloom. On the west side, bloom varies, depending mostly on how far off the valley floor the almonds are. The higher up from the valley, the warmer the weather tends to be, so bloom moved a little faster in those locations.


“In places, Nonpareils and all the early varieties are in petal fall. You can pick out the rows of Winters from a distance because leaves are out enough to get that green effect. That’s kind of typical with Winters.


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“As of right now (2/16), I doubt if much fungicide has gone out. Most people have probably been waiting for rain before they act. It’s been really dry, especially on the west side where winds have been blowing. I don’t know that we’ve really had any dew events at the Nickels Soil Lab this year. If any dew developed on the west side, it might have been in swales.


“The National Weather Service put out a freeze warning – not just a frost advisory – today, and it covers much of northern California and into the northern San Joaquin Valley. They are predicting low temperatures from 26 to 32. If lows drop to 28, that will nip some stuff. If it goes to 26, you could run into trouble with almonds and certainly expect some yield loss.


“Trees could compensate for some shed, of course, but we would have a real problem if it goes any lower. Forecasts right now vary, depending on the source. AccuWeather says it could be down to 23 on Monday night in Yuba City. One well-regarded ag weather service, I’m told, says its models can’t tell us for certain whether the range will be between 23 and 28 or between 26 and 32. Evidently, you can read those models in different ways. That kind of illustrates some of the uncertainty right now.


“All that said, we know it’s going to get cold. We’ll start seeing this cooling trend over the weekend. Tomorrow (2/17) the highs are supposed to be around 68 or 69 in the valley, then get 10 degrees colder on Sunday as a frigid air mass moves in from the north.


“Some growers don’t have much in the way of frost management options. Drip irrigation is a great tool in terms of efficient production but it doesn’t do much when it comes to reducing frost injury. Beyond that, some people may not have water.


“In the past, a few big growers on the west side hired helicopters to push down inversion layers, which might be an option next week – assuming there’s an inversion layer to push. But having a helicopter and pilot on standby is expensive and not an approach for the typical grower.


“This is the first time I’ve been involved in anything like this in the 7 years I’ve been working in almonds here. We’ve had cold conditions in parts of the lower Sacramento Valley, but this is potentially more serious.


“The degree to which sub-freezing temperatures affect almonds depends partly on the crop’s stage. If this were April, 30 to 32 would be dangerous. But at bloom you really don’t have to worry until lows slip into the 20s. At 24 to 26, it only takes a half-hour for unprotected orchards to really be in trouble.” 




California Almonds: Frost Protection – The Fine Points 2-17


California: We Need More Bees Than You Might Think 2-16


California Almond Shipments Set Record For January Period 2-15


California: Almond Leadership Program Kicks Off 10th Year 2-14 



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