Serving California producers and their professional advisors, covering almonds, pistachios, walnuts and other tree crops. Sponsored by the California field staff of BASF.
Owen Taylor, Editor
A large drop has occurred in numerous areas, based on this week’s reports.
A range of factors are being cited – heavy winds, torrential rains or perhaps not enough time for bees to pollinate all the flowers. But several of our contacts also say that fertilization processes were perhaps compromised by warm conditions and/or there simply wasn’t enough time between pollination and complete fertilization to guarantee the nuts' viability.
The drop is quite obvious in places, although it’s too early to predict any effect on overall yields. This shedding is not associated with the so-called June drop when trees throw off some nuts to balance their potential crop and available resources, a couple of people noted.
Rain was expected over the weekend (3/19-20), and some growers were applying fungicides ahead of that. The post-petal-fall applications will begin gearing up later in the month where those treatments are part of the program.
Leaffooted bugs have been found in Kern County. See comments by Dan Prentice.
A bacterial leaf spot is turning up in some trees. See comments by David Doll.
Walnuts and pistachios are pushing on a wider basis. More copper treatments are ramping up in walnuts.
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Mark W.F. Carter, PCA, Agri-Consultants, Los Banos: “We’re starting to see almond hulls sizing a little. Two fungicide applications have gone on. Unless we see a chance for a series of rains coming up, that may be it. The forecast says there’s a chance early in the week, but if it’s a short event and wind comes in behind it, we probably won’t do anything as far as fungicides go.
“We’ve been trying to apply fertilizer but have had 2.5 inches of rain over the last 8 to 10 days from 2 major storms, so we want the orchards to dry out again before we really start with fertilizer. Fresno already has had 13 inches of rain, and the annual average is something over 11 inches, plus we still have some chance of rain through March and into April.
“They’re calling this the Miracle March. If we get any more major storms, it certainly will be. This is the first time in 2 years that I’ve seen water in certain rivers.
“With the storms, some just-pollinated nuts probably were knocked off, more due to heavy rains than winds, I think. In one case I’m told it rained an inch in 15 minutes. Growers are finding a lot of small nutlets on the ground that I think were just pollinated. Nobody can say how many of them would have stuck, and some of those maybe hadn’t been pollinated. With this year’s flash bloom – especially in Nonpareils – it was all over within about 10 days.
Over the last couple of weeks we’ve treated alfalfa for alfalfa weevils. It’s been too wet to start planting cotton. We’re having to fly on glyphosate on some beds to clean up weeds.”
Franz Niederholzer, UC Farm Advisor, Sutter/Yuba Counties: “We’re out of petal fall in almonds. The spur leaves have pretty well filled out on the bottoms of trees and are approaching that point on the tops. No white is showing in almonds as you drive through the county. It’s also been amazing how much nuts have grown. Nothing is at an inch yet (as of 3/18) but I can regulary find them at a half to three-quarters of an inch and out of the jacket.
“The forecast calls for rain from Sunday to Tuesday, and it’s that time of the year when we’d normally expect it. Some growers are spraying ahead of that and maybe going with a material that provides some reach-back after that last big, long storm system. We had just shy of 4 inches of rain over a 10-day period in early March on the west side, which is a third of our annual rainfall.
“Some trees went down in the storms and certain orchards sustained more loss than others. We’re also finding drop, mainly stuff that never made it out of the jacket. That’s not just flower. What we’re seeing on the ground includes some nuts that made a little size. This definitely wasn’t your June drop, which actually ends up being the April-May drop for us, and that drop is more associated with trees allocating resources and letting go of excess nuts.
“Walnuts are coming along. Growers might be applying blight materials ahead of this weekend rain, depending on how far along things are. In our Fords and Gillets at the Nickels Soil Lab, a big portion of the buds are at prayer stage, maybe approaching 100%, and the Tulares are somewhat behind them. The Howards are at about 10%. The way wet weather has been shaping up, we might go ahead and treat the Howards when we make applications on those other varieties.
“We still have white petals in the prunes, and it looks like a decent to good crop. We tend to have better prune crops in wetter years than when we have a lot of heat.
“A quick reminder: this year our Nickels Field Day is set for the morning of May 19. After lunch we will have a second field day on organic production. This will be 2 different programs but everybody is invited to both. Please put that on your calendar. Details will follow.”
David A. Doll, Pomology Farm Advisor, Merced County: “We’re starting to see sizing and development of the fertilized almonds, and it should be obvious now which nuts fit into that category.
“I am getting a lot of calls about nut or flower drop. On one hand, we don’t think the nuts that are dropping are fertilized. Before anyone jumps to conclusions, you also need to take into account the initial floral density to get some perspective about how much has actually dropped as a percentage of what we had at the end of bloom.
“But we also need to keep in mind that it can take up to 5 days, on average, for the pollen to actually fertilize the almond bloom’s ovial. During that period you could have a degree of failure, especially with warm temperatures.
“Although we had good bee hours, that doesn’t necessarily mean we had as many good hours for fertilization to be completed. I kind of thought we did, although I am seeing cases where trees are holding hardly any nuts, so I fully understand farmers’ concerns. Maybe we had enough time, maybe we didn’t. Time will tell.
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“The flash bloom may have limited how much pollination occurred, given how quickly it happened. One veteran farm advisor in the Sacramento Valley said this was the fastest bloom he’s seen in 35 years, and he has the memory of a Rolodex. But long-time farmers and crop advisors from Bakersfield to Merced also are saying that this is about the fastest bloom they have ever witnessed, too.
“Did we really have enough time for the trees to fully sync for good fertilization? Again, we’ll know more in a couple of weeks. It’s still a little early to get overly excited, and people should realize that this drop isn’t due to disease or something they did wrong. This is an effect of this season’s circumstances.
“Essentially, we’re at full leaf expansion, so people are certainly thinking about making that first application of water to get fertilizer out. You still need to base timing on soil conditions, not just because it’s time to apply fertilizer. Wait until soils dry out a little. We have a growing set of data indicating that overwatering can adversely affect the development of the root architecture, so be patient.
“We’re also again observing a weird bacterial leaf spot, something that tends to develop in wet springs. You can find more about this from a 2014 post at thealmonddoctor.com (see Links). You'll find relatively large spots on the leaf at margins or veins, and these spots tend to develop on the tips where water collects. Size can vary from the width of a pencil eraser to maybe three-eighths of an inch. In some cases it causes leaf drop. However, leaf drop occurs late enough that the loss probably has little or no effect on yields.
“Walnuts and pistachios are moving. Everything is early. Even though it looks like we had ample chill, those really warm conditions in February pushed things along.
“In the last 10 days I’ve poured 4.1 inches of water from my backyard rain gauge, although farmers are mostly talking about 3.5 inches. Our annual total in the Merced area is 10 to 12 inches. The forecast looks clear for a while (from 3/18), but we’re hoping more rain will fall.”
Dean Striebich, ASI Consulting, Fresno: “The bloom is over. With all the wind, a lot of small almonds dropped, but that wasn’t unexpected with this kind of weather. It’s still too early to tell for sure, but the Butte-Padres and the Nonpareils seem to be off a little. We haven’t gone through the June drop yet, so we’ll have to wait to see how that goes.
“Montereys have hung a good crop again. I haven’t looked intensively at the other varieties yet, but things appear lighter overall than what we’d hoped for. We’re also seeing those cases where some trees shed more than others in the same variety in the same block, and it’s always hard to explain those differences. The almond foliage does look good and things are growing well. Pistachios are leafing out.
“Rain has varied. A half-inch fell last weekend (3/12-13), with reports of three-quarters in places, but in other areas the amounts ranged from none to a few hundredths.
“Tomatoes are going in. A couple of growers say they will start planting cotton next week, and they probably will have more acres than originally expected. Even though cotton prices aren’t that good, other choices are maybe less attractive, so farmers don’t feel like they have a choice. We’ll really be watching inputs in cotton.”
Dan Prentice, Prentice Ag Consulting, Bakersfield: “I found some leaffooted bugs yesterday (3/17) in almonds. That was the first time this year and I found them in the same week when they initially turned up in 2015. I actually looked hard all week, then finally found them in a spot where I thought they would be, based on history and also other factors.
“The spot was next to some neighborhoods, and I believe the bugs overwintered in back yards in ornamental plants. From there, they would move into the crop once the nuts sized up. I’ve also been looking for them in another likely place that is near palm trees where the bugs might overwinter. So far, though, they haven’t turned up in those almonds.
Spider mites are around but are fairly light compared to pressure at this point in the last few years. In places, they’re easy to find but not in high populations. In other locations I can hardly find any at all. Thrips have been around, too, and seem to be keeping things in check.
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“Just about everyone made 1 to 2 fungicide applications through bloom, based on the rain that came through. No rain is in the forecast right now, so everybody is holding tight. In a couple of weeks we’ll start that fungicide shot that’s 5 weeks past petal fall. That will mainly be for rust but also for alternaria where we have a history of it. That will be the first of our 3 treatments for alternaria.
“Depending on the weather, some guys will choose not to do this upcoming fungicide application. But other growers will go ahead with the application. We generally recommend this post-petal-fall treatment to address a wide spectrum of diseases.
“So far, we haven’t seen a lot of shed, but I can tell it’s coming. We did lose a few nuts during a windy day 7 to 10 days ago. Mainly, we’re just finding a smattering of nuts on the ground, nothing that looks like real shedding.
“Pistachios are just pushing.
“In the last 2 weeks we’ve received maybe 0.35 of an inch of rain, not as much as people hoped for. Over the last couple of weeks the state radar map would be covered up with red and yellow showing rain – except around Bakersfield.
“Blue alfalfa aphids are starting to move into alfalfa some. We’re getting close to treating.”
Aaron Heinrich, Independent Crop Advisor, Agronomic Systems, Escalon: “Most growers have at least 2 fungicide sprays on and a number have either put on a third or plan to do so. We’re expecting rain this weekend (3/19-20), although it’s anybody’s guess how much. This rain has been in the forecast for a week, but the chances seem to change by the hour, from 80% with thunderstorms to just 20%.
“The general idea is that a fungicide provides protection for 13 to 14 days, so farmers want to get another application out to freshen up their defenses, especially leaf protection.
“We received more than 4 inches of rain over the last couple of weeks, which is substantial for us, and we haven’t had rain like that for years. This next rain is supposed to start Sunday (3/20) and go into Monday, based on the last report. After that, they’re predicting 80-degree weather with no rain in sight. Based on that, some people won’t apply a fungicide and just ride it out.
“We’ve had a huge drop, and I think it’s partly due to bloom and pollenization going so fast. There wasn’t enough time for fertilization to fully take effect. It started off looking really good, but then the wind picked up over the last few days and the drop started.
“Walnuts have started pushing good and we’re already spraying copper on the early varieties. We’ve gone by ground on the Paynes and will come back with a second application by air on those trees. Vina is pushing hard, too, and will be coming up right behind the Paynes.”
AgFax Tree Crops, formerly AgFax Almonds, is published weekly during the crop production season.
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