Almonds – Hull Split Approaches, Timing Is An Open Question – AgFax Tree Crops

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Owen Taylor, Editor


Hull split is approaching, but when to expect it remains an open question. After a series of years with earlier-than-normal splitting, it’s generally thought that this year’s split will start a bit later and also closer to the historic average timing.

Disease pressure remains relatively low in most areas. That’s not to say more rust or alternaria symptoms aren’t showing up in places. But our contacts generally say that disease pressure so far is lighter than expected, considering wet spring conditions.

Pest activity hasn’t picked up much, based on this round of calls. In some blocks, spider mites may trigger treatments before hull split sprays. But based on what they’re seeing now, crop advisors say that they can mostly hold off on a miticide until hull split sprays crank up next month.

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Gary Gliddon, PCA, Treevine Consulting, Modesto:

“In May, I recommended that my growers hold back on a fungicide application. Trees were clean and I didn’t see an immediate reason to treat, even though it had rained a good deal. And after that, a lot more rain fell than anyone expected.

“At least so far, that appears to have been the right call. Trees are just as clean as they were 4 weeks ago. The one exception is an organic grower who has had anthracnose in his trees in the past. We did spray his almonds with a product that he could use and that had anthracnose on the label. We hoped it would work but anthracnose is showing up again in those same fields. Otherwise, no problems.

“It’s June 20 and we’ll probably look at our first hull split spray two weeks from now, depending on how soon hull split comes this year. There’s a lot of thinking that it will be a little slower in starting but the bloom was spread out and we had early flowers. If those set, we might have the first nuts splitting sooner than might be thought.

“Usually, we see the first splitting around June 28, but I’ll be looking for them before then. I want to roll fast and probably will be lining up sprays in 10 days. With growers who can’t get in orchards pretty soon after irrigation, I’m telling them to make sure their ground is dry between June 30 and July 10 because that’s usually the window for our hull split applications.

“Our NOW traps are still pretty quiet. Some are running zeros. When we do find moths, counts are low. I do expect that to change soon, though. The degree day accumulations indicate that egg laying should begin around the Fourth of July. It’s been warm, and that will accelerate things, I suspect.

“I really haven’t seen any spider mites yet, but I am in an area that doesn’t have many mite problems. We will include a miticide with the hull split spray, plus a fungicide for hull rot and rust, along with something for NOW.

“In walnuts, we want to do a botryosphaeria spray. Because codling moth pressure is low, we’ll probably include something that kills husk flies. More than likely, I’ll make an earlier start on husk fly because we have Chandlers, and I think that husk flies are more of a challenge in that variety than codling moths. The only indication of blight right now is in a block of Howards. All the Chandlers look pretty good.”

Dan Prentice, Prentice Ag Consulting, Bakersfield:

“I haven’t seen anything splitting yet, not even blanks, but we’re anticipating that it will start around the Fourth of July, give or take a day or two. That’s later compared to the last two or three years but more like the long-term normal timing.

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“No major pest problems right now. Mites are starting to show up but they really are at low levels for this point in June (6/21). As things look, we’ll include a miticide with the second hull split spray where we’re doing two applications. In a few instances, we’ll include the miticide with the first spray.

“I don’t have any places where I feel pressured by mites. Over the last few years, mites have been really light going into hull split, to the point that I’d be tempted to leave out a miticide. That, of course, would be insane. But as things have played out, we tend to find mites around August 1, almost regardless of what we’ve done. At that point, you can’t do much and growers are into harvest.

“Rust is coming up in 2- and 3-year-old trees and we’re treating that.

“Pistachios really look good right now. We finished mealybug sprays two weeks ago and aren’t seeing any issues. I can find citrus flat mites just occasionally, nothing approaching threshold. A few armyworms turned up in tomatoes about 3 weeks ago. We treated those and haven’t seen anything since. We applied a lot of fungicides after all that rain and aren’t seeing any disease in tomatoes right now.”

Sara Savary, PCA, Crop Care Associates, Fresno:

“We’re holding off on most treatments until hull split sprays, which are probably a couple of weeks away (from 6/21). We’re applying a fungicide right now where we have alternaria. In those cases, the gap was just too wide between the last application and when the hull split sprays go out.

“A little leaf rust is popping up. Usually, we’ll include a fungicide at hull split to take care of that and cover hull rot, too.

“Mites are slowly building in trees, in some spots more than others. I’m hoping we can wait for hull split timing, although in places that might not be feasible. I keep waiting for sixspotted thrips to come in and clean up mites. I do that every year but it usually never happens soon enough.

“In walnuts, we just finished our 2A codling moth spray. I’m seeing very few mites in walnuts and did not include a miticide. Walnut prices aren’t great and I’d rather not spend the money unless it’s necessary. Hopefully, that will work out. The key will be to avoid stressing the trees.

“We usually have our first bloom in cotton around the Fourth of July and the crop seems to be on track for that this year. I had to spray for lygus due to the rain delaying alfalfa cutting, which gave lygus more time to build. When growers could cut, everyone jumped in at the same time, and lygus moved into cotton and we had to clean them up. So far, retention is good.

“In alfalfa, I just found my very first small beet armyworm egg mass on a leaf, so we can probably get through the next cutting without an issue. In tomatoes, I saw a very small yellow-striped armyworm egg mass on a leaf. I’m also finding cabbage loopers but not enough to spray. Not much thrips activity in tomatoes.”

Aaron Beene, PCA, Simplot Grower Solutions, Merced:

“The weather is very pleasant. In the last couple of weeks, we have had a few hot days but then things cooled down, especially at night. Plus, it rained a couple of weeks ago. All of that has combined to keep mite pressure way down in our area.

“On the flip side, we’re dealing with a lot of weeds and growers are spraying orchard floors to clean them up ahead of harvest. We’re also putting out ant bait in areas where we tend to have bad pressure. I like to apply an IGR-based bait a couple of months before harvest. But then I come back with a knockdown-type bait about 2 weeks before harvest in those locations where we have more issues with ants.

“I really thought by now that rust and scab would be showing up in an obvious way but we haven’t seen much to speak of quite yet. But we’ve had somewhat cooler weather, and rust really starts to flare up in July. So, we’re keeping an eye out for leaf diseases. With those wet conditions in May, I still anticipate that disease will develop.

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“Our hull split sprays will likely start in 2 to 2.5 weeks. Things are probably running a week behind normal, and I’m thinking the earliest applications will start in the week of July 8.

“Last year – after 3 or 4 years with heavy NOW pressure – I started going with a two-shot hull split spray program. We’ll spray the second time about 2 weeks after the first round. With the first spray, we’ll probably include something for hull rot where we have a history of it. Trees have added a good deal of vegetative growth this year and we’ve had plenty of moisture, so hull rot could be an issue.

“In walnuts, we’ll put on a miticide and include a material for codling moths. That will be for the 2A codling moth timing. This is a pretty good crop. Some of my early-blooming varieties were hit by what I would call side blight and blossom end blight and these nuts are starting to shed.  Otherwise, potential looks really nice.”

Jhalendra Rijal, Area IPM Advisor, Northern San Joaquin Valley:

“We are approaching the first hull split spray timing for NOW control in the northern part of the San Joaquin Valley. The estimated hull split spray timing based on the spring egg laying biofix – April 9 for the northern SJV – is 1200 degree-days, which falls squarely on the Fourth of July this year.

“Take that as a reference only, not the absolute timing for anyone else’s orchard. NOW activity and crop development is different among orchards. I also ran the UC hull split prediction model for the Modesto area with full bloom timing on February 20, and the predicted hull split date for Nonpareil came out as July 13.

“So, there’s a bit of wiggle room between these two timings, and you might see similar variation in different locations when you run these projections.

“For each orchard, it’s critical to track NOW activity, especially in egg and female traps. If moths are ready to lay eggs but hull split hasn’t started, wait and spray when the split occurs. If moths are laying eggs in egg traps and nuts are at hull split, you need to cover those susceptible nuts by spraying at or before 1% hull split.

“The meaning of ‘hull split’ in this case is that the opening of the hull should be about three-eighths of inch wide (see hull split progression in this link), and it can be determined by sampling nuts from the top southwestern quadrant of the trees. The UC NOW guidelines go into more detail.

“Anyone who’s dealt with this knows that NOW control is a tricky business, and decisions should be made based on what is happening in the specific orchard. So, surveying hull split and monitoring NOW activity – especially egg laying – are critical for spray decision. My preference is to go a little on the earlier side than the later side if you plan to spray twice and also will use longer-residual materials.

“Remember, too, that navel orangeworm control is not just about which insecticide to use. It’s more about when and how to use the materials you select. And how you spray matters, as well – keep sprayer speed at 2 mph or less, go with enough water volume for better coverage and spray only in low wind velocities. Finally, proper equipment calibration brings all the pieces together.

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