California – Almonds – Hull Split Within Sight – AgFax

    Image from David Doll, University of California Cooperative Extension

    • Here is this week’s issue of AgFax Tree Crops.
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    Owen Taylor, Editor
    Jenny Holtermann, Contributing Editor


    Almond hull split is within sight, and the very first hull split sprays will crank up towards the end of the week, particularly where larger growers have plenty of acres to cover. Within two weeks, treatments will be underway on a wide basis. Blanks already are splitting on edges in the lower San Joaquin Valley.

    Rust and alternaria remain a problem in select locations, and fungicides will likely be included in hull split sprays where these issues have arisen.

    Hotter weather has clearly entered the forecast. Temperatures above 100 will be more the norm in parts of our coverage area through part of the week. At the least, mid-90s are in the cards.

    Spider mites seem poised to build during this heat wave, and miticides will be included in plenty of tank mixes.

    From our sponsor



    Chris Cucuk, Cucuk Consulting Inc., Bakersfield

    “Almond hull split is fast approaching. A few blanks are starting to split along the end rows. Next week, almonds will begin progressing rapidly, based on 100-plus-degree highs in the forecast. Currently, we plan to begin hull split sprays in the first week of July. However, the heatwave could ramp up that timing much faster.

    “Spider mite populations remain low. Last week, the populations did pick up a bit, but they still are minimal. But we could see that change next week, again due to much hotter weather. Growers with mite concerns will add a miticide to their hull split sprays.

    “Ant bait has gone out or is currently being applied, and all of my growers are going with a bait.

    “We are finding rust and alternaria at variable levels throughout the area. We do not generally see rust in our area this time of year, and most areas were treated for rust about two months ago. Growers who have rust this year will add a fungicide to their first hull split spray in areas where rust is more apparent.”


    Aaron Heinrich, Independent Crop Advisor, AgriWest, Inc., Escalon

    “Walnut growers are gearing up for the second generation of codling moth. We have not set a biofix yet for the second flight, and trap counts remain low. The first flight appeared to have been longer than average and might be a factor in low counts now. A codling moth generation in the Central Valley can range from 800- to 1300-degree days. We should see a biofix this weekend. The 250-degree day spray timing is a week to two weeks out for the 2A flight.

    “We expected moth counts to increase by now. However, it’s been very windy, which tends to lower trap counts.

    “Across the hundreds of husk fly traps, we have only caught one husk fly. We do expect these counts to rise as temperatures ramp up. Some walnut growers did treat select blocks for European red mite, and pressure was high enough in places to warrant applications.

    “Many growers are busy with weed spraying, attempting to control the growing populations across almonds and walnuts.

    “Mite populations are starting to build in almond orchards in our area. Even with increasing temperatures, the mites in most blocks will not have enough time to build pressure to justify a treatment before hull split. Based on a 1200-degree day model, we can expect the next navel orangeworm flight in San Joaquin County at about July 3. That will coincide with the first 1% of hull split timing on nonpareils.

    “Over the last week or two, growers have started to see rust show up. Issues developed where growers may have missed an early fungicide application. Growers with high pressure will be able to add a fungicide to their hull split spray, although the effectiveness at that timing is somewhat questionable. Others will add foliar nutrients, as well.

    “We do see small amounts of limb breakage in our area. However, it’s not as much as you would think when compared to the reports of the large crop load. Growers are propping up branches in some areas. The almonds are heavier during the nut fill process and we are past the heaviest point for almonds. Once the hulls split, the branches will lighten up.”


    Luke Milliron, Area Sustainable Orchard Research Advisor, Butte, Glenn and Tehama Counties

    “The high temperatures in the forecast for this week didn’t quite hit what had been expected, but a heatwave is coming this weekend and will continue. We don’t see signs of early almond hull split yet. The standard timing in our area leans towards July 4, although this year it could be later.

    “To reduce hull rot and move to harvest quicker with less navel orangeworm infestation, growers can impose moderate water stress. The best timing approach is with a pressure chamber or commonly used pressure bomb. Target -14 to -18 bars from the onset of hull split. Go at that range for roughly two weeks.

    From our sponsor…


    “With these cooler temperatures recently, mite pressure in almonds remains low. But with this predicted heat, we sure need to be prepared if populations quickly rise. New research on monitoring for presence of sixspotted thrips – using those small yellow sticky cards – helps fine tune spray decisions. David Haviland discussed this during a recent podcast.

    “Leafing failure in Montereys still isn’t improving in three orchards we are monitoring in Tehama County, and the cause largely remains unknown.

    “Walnut yield potential looks good. Walnut blight remains low this year despite the early rains that tend to build pressure. Growers have hopefully gained results with more vigilant bactericide programs that lowered both disease levels this year and inoculum levels that would be carried into next year.

    “Some PCAs report a recent uptick in codling moth counts.

    “I received a report of a yellowing/collapsing canopy, which likely was caused by overwatering, maybe in concert with phytophthora.

    “In prunes, start looking for the first healthy fruit to begin developing color. We can expect to start harvest roughly 30 days later. Hot conditions are in the forecast, but with prunes, cooler weather hastens fruit softening and harvest maturity.”


    Dan Prentice, Prentice Ag Consulting, Bakersfield

    “Temperatures have increased this week and are expected to be well over 100 through the weekend and into next week, based on the most recent forecast I saw. Temperatures just at 100 degrees shouldn’t alter hull split timing significantly. In the past when temperatures moved well over 100 for an extended period, it actually slowed the progression of almonds.

    “Starting at the end of next week, June 26, the earliest growers will begin hull split sprays. The following week, the first week of July, all growers will be putting on a hull split spray. The almond price this year will partly influence how many navel orangeworm sprays growers will make.

    “All of our almond growers this year will add a miticide to the hull split spray. Mites are just starting to increase across most fields now, so it’s best to include a miticide with those applications. Mites began flaring in a couple of cases over the last few weeks, and we did have to treat in those locations.

    “Alternaria is following its historical patterns in terms of where it’s turning up this year. The pressure is sporadic but widespread in areas where we’ve found it in the past, and alternaria is causing damage in 50% of the acreage in our area.

    “During nut fill, growers propped up heavy branches. Orchards with 4-year-old trees are the worst and still have drooping branches. The younger orchards loaded up this year with crop, and we’re seeing those limbs breaking. Tying and pruning methods play a role in the effectiveness of branch support.

    “Pistachio orchards remain clean. Two to three weeks ago, pistachio growers treated for mealybug and included sulfur for citrus flat mite. The treatment has kept the citrus flat mite populations low. In isolated blocks, alternaria increased, and we will apply a fungicide in those orchards.”


    Jhalendra Rijal, Area IPM Advisor, Northern San Joaquin Valley

    “Temperatures are on the rise as we end the week, and we will head into next week with 100-plus highs for the next 7 to 10 days. Concerns about higher temperatures aren’t uncommon in June. This could prompt more navel orangeworm activity earlier, plus increase mite pressure.

    “According to the degree-day model based on spring NOW activity, the second flight for male moths could begin any day now. Moth activity will increase for another 2 to 3 weeks and damage newly-split almonds. Most importantly, paying close attention to female moth activity in traps is critical in tracking egg-laying patterns.

    “Almond growers are gearing up for the first hull split sprays, with projections for the first week of July in our area. Monitor hulls for guidance about when to treat. Don’t just judge timing on insect movement. Last year, the 1% hull split of Nonpareil was closer to July 10. July 6 is the projected hull split initiation time for the Modesto area this year, based on the UC model.

    From our sponsor…


    “When we talk about 1% hull split, that means an estimated 1% of the total nuts on the tree or orchard have a 3/8-inch suture opening.

    “Mites favor a hot and dry environment. In the last several years, mite populations built heavily later in July or even in August in the northern San Joaquin Valley. This timing would suggest that the second hull split spray may need to include a miticide. However, monitor mite populations and conditions to closely time treatments in your own orchards.

    “Avoid using pyrethroid so we can give sixspotted thrips time to work their magic. Sixspotted thrips have proven to be a very reliable predator in almonds across the Central Valley.

    “Walnut growers report variable codling moth populations across climate and soil types throughout San Joaquin County. The heat can influence codling moth timing, and we have seen variable populations. The first overwintering flight in April and May varied greatly. Some PCAs mentioned catching 100-plus moths in a week, while others found minimal numbers or none at all.

    “It wasn’t easy to set the first biofix. The early-season cooler temperatures in mid-April played a part in codling moths’ late start this year. In the northern San Joaquin Valley, we just entered into the 2A flight, with a June 16 biofix date. Based on that, if we need to spray the second flight at 250-degree days, that would be in the latter part of next week. It’s essential to both monitor trap counts and to sample nuts for codling moth activity.

    “Husk fly monitoring remains important. Traps started going out June 1 or even earlier. Growers with a history of husk fly in the past will generally see it year after year, and July and August are more concerning periods for husk fly in walnuts.

    “Leaffooted bug immatures are showing up in navel orangeworm female and egg traps. At this point in the year, they cause no significant damage.”


    Nathan Stewart, PCA, AgVantage Consulting, Inc., Visalia

    “The moderate temperatures have helped trees develop faster this year when compared to last year. We have not had excessive triple-digit temperatures this season, and that’s given us positive growing degree-day accumulations. We might end up being a few days ahead of typical hull split timing.

    “Hull split will begin on the sandy soil types, quite likely in the first part of July, which tends to be the normal timing for our area. Last year, we were slightly behind that timing. We are approaching the navel orangeworm flight. In a few blocks, we’re applying flowable mating disruption. These are in areas with poor sanitation practices.

    “Most growers have finished fertilizing almonds until the post-harvest applications. A few locations did need an additional dose of potassium. Growers are keeping water on the trees as we approach a heatwave starting this weekend.

    “Mite pressure in almonds has been relatively low. One block did warrant three miticide applications for a population that couldn’t be brought under control. But mite numbers are beginning to be more apparent, overall, and that trend will continue as temperatures rise. A miticide will be included in hull split sprays as needed.

    “Before the middle of June, we had areas that required treatment for alternaria, but pressure has eased and we haven’t seen anything since. Rust has not been an issue in our area this season, luckily. Growers are winding down on applying ant bait, and the goal is to wrap it up a month before harvest.

    “Walnut orchards are in the middle of the 2A codling moth flight. Growers are making their treatments and plan to finish by June 22. Growers will apply irrigation behind the applications. Trap counts just started to rise last week but remain minimal. We have one hot spot towards the Ivanhoe area. If the numbers continue to increase there, we will target the 2B and the 3A flights, which isn’t something we normally need to do.

    “Husk fly traps are in place in walnut orchards. PCAs report no findings yet. In walnuts, we’re finishing up 60% of the fertilizer application needs for nitrogen before the nuts harden off. The remaining nitrogen will go on before harvest.

    “Pistachios are near the 1700-degree-day mark, and in select spots we have concerns about navel orangeworm. We will monitor population dynamics to see if a spray is necessary. We went through a staggered bloom this year that also went longer than usual. With that, we anticipate early splits, which could cause an increase in NOW pressure closer to harvest.

    “Pistachio growers are finishing their third fertilizer applications. Nut fill will begin in 2 weeks when the embryo turns a hue of green. Irrigation demands will increase as we approach nut fill. The shells have hardened off and plant bugs will be less of an issue going forward.”

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