Almonds – California – First Hull Split Sprays Fast Approaching – AgFax

Thrips on an almond leaf last week with plenty of spider mites for food. Photo: John Moore, PCA, Growers Crop Consulting, Bakersfield.

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Owen Taylor, Editor
Jenny Holtermann, Contributing Editor

OVERVIEW

The rollercoaster weather ride continues through much of our coverage area. Highs during the week regularly topped 100, but the weekend forecast put temperatures in the 80s and even mid-70s for Sunday.

Spider mite populations in almonds remain sporadic. Predatory mites and sixspotted thrips are holding spider mites in check in some places but have been giving up ground in others. Multiple miticide sprays have gone out in some orchards.

Hull split sprays will start in places before the end of this month, based on projections by our contacts over the last couple of weeks.

In pistachios, chinch bugs are still hitting young trees in scattered orchards.

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CROP REPORTS

John Moore, PCA, Growers Crop Consulting, Bakersfield

“With these hotter temperatures lately, insect numbers are increasing. This week, we average 150 peach twig borers in our almond traps. By comparison, PTB catches averaged 40 last week. Typically, it would be unusual to find a trap with 200 PTB catches in a week, but that’s been somewhat normal this week.

“We will continue to monitor traps. If high populations become consistent, we will consider an early hull split spray timed with the next PTB flight. That would put us towards a June 20 application, but we will see how the PTB trend in the meantime.

“Spider mites vary. In certain areas, mite populations are running high, but in other locations the pressure is minimal. In areas with historic mite issues, it’s a struggle this year to keep populations under control. Almond orchards that we sprayed 9 to 14 days ago will need another application. Some orchards have already been sprayed for mites a third time.

“Predatory mites and sixspotted thrips are often in the mix, but they can only do so much against high mite populations. Some growers will add another miticide and others will try to hold off until early hull split.

“Areas with signs of alternaria earlier in the season – especially in the Independence variety – are now showing mite issues, and heavy mite populations have built in the alternaria wounds. Where growers took measures for rust and alternaria control in the spring, we’re not finding that spider mite pressure.

almond-sixspotted-thrips-mites-john-moore-20200605[1]_1586920.jpg
Thrips on an almond leaf last week with plenty of spider mites for food. Photo: John Moore, PCA, Growers Crop Consulting, Bakersfield.

“In two young almond orchards, we’re dealing with high numbers of false chinch bugs. Initially, they were sporadic across the fields, but within a week the population became a huge problem. The tree wraps were covered, and the populations were so heavy that they looked like used coffee grounds. The chinch bugs move up the crotch of the trees, then onto the scaffold branches where they suck on the leaves. We were able to fly on a spray to control 90% of the bugs.

“Several pistachio growers sprayed for botryosphaeria and plant bugs. Nuts were falling to the ground due to plant bug damage.

“Our codling moth pressure in walnuts has been low. Next week, we will pull codling moth traps and replace them with navel orangeworm traps, which we will monitor until almond hull split. Lately, we’ve seen less codling moth issues but more navel orangeworm presence in walnuts.”

 

Chris Morgner, PCA, Agri-Valley Consulting, Merced

“Almonds are nearing the end of nut fill, and most are pretty solid now. By and large, our orchards are pretty clean. Temperatures have climbed well over 100 degrees, and irrigation is the main thing going on in almonds right now.

“We did come across half a dozen almond orchards with rust issues, and we treated those fields before rust could progress more.

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“We continue to monitor for mites. Beneficials have been controlling mites in most orchards. Those are mainly sixspotted thrips and a few predatory mites. One block did require a treatment, but predators have otherwise been taking care of mites, which is reassuring.

“Younger almond orchards are a different situation. In first-leaf orchards, we always end up with spider mite pressure, and it’s rare that we don’t have to spray a first-year orchard for mites. We encourage growers to keep orchard centers undisturbed after April, with no disking, floating or other activity that stirs up dust. We are planning miticide applications in first- and second-leaf orchards where we have concerns. In third-leaf orchards, we’ll make applications where problems persist, but that’s not as common.

“Planning is underway for hull split sprays in our Nonpareils, and that is trending a few days ahead of July 1. Strategy, materials and navel orangeworm phenology are all factors to consider. Based on the predictive models, this next generation of navel orangeworm will likely coincide with hull split.

“Growers who opted to not front-load fertilizer in March, April and May are still applying small amounts. They increased fertilizer during nut fill and will back off to smaller quantities in June through August. The almond trees are more likely to take up needed nutrients as they utilize water during the warmer months. Growes are going with about 15% of the year’s total in July and in August ahead of harvest but won’t apply anything after harvest.

“In walnuts, codling moth counts are low. Husk fly traps are going in place. Parasites are keeping aphid pressure to a minimum. We find it easier to prevent botryosphaeria with a fungicide spray than to wait for it to gain a foothold. Growers with drip irrigation and micro-sprinklers are applying small amounts of fertilizer through their systems every week or every other week as needed.

“A few pistachio orchards required mealybug treatments. Those growers are adding a material for botryosphaeria.

“Certain fertilizers are also applied through the irrigation systems. We emphasize nutrient plant health during pistachio nut fill, which runs from the end of June through early August.

“Cotton is at 8 or 9 nodes. Lygus counts remain low, with minor square loss.

“Tomato growers aren’t dealing with pests yet. The plants are mostly well established, despite the wide range of planting dates from the beginning of April through May 20. We sprayed fresh tomatoes for thrips as those populations developed, but worms haven’t warranted action.”

 

Franz Niederholzer, UC Farm Advisor, Colusa, Sutter and Yuba Counties

“Over the last couple of weeks, we’ve been in a pattern with hot temperatures during the week and lower temperatures over the weekend. Last weekend (5/30-31), thunderstorms developed, with a half-inch of rain in places, then the temperatures bounced back to 100 this week. But this weekend (6/6-7), we’ll drop into the mid-70s with a 20% chance of rain.

“I haven’t heard of or seen any uptick in disease following the scattered rain this past month, but it can take several weeks for symptoms to show. Despite cooler periods over the past couple of weeks, evapotranspiration numbers are running at 100% to 110% of average.

“Growers should start considering when to taper down on irrigation if they plan to take a strategic water-deficient irrigation (SDI) approach as we move into early hull split. The target for hull rot prevention with SDI is -14 to -18 bars on the pressure chamber once Stage 2B hull split arrives.

“With heavier soil and sprinklers, you’ll need to reduce total irrigation soon to reach those target numbers by the end of this month. In orchards on drip irrigation or lighter soils, you probably don’t need to start as early, given a smaller soil water bank. Don’t try this without access to regular pressure bomb scheduling.

“The overall strategy is to slowly back off on the length of irrigation sets, not to eliminate sets. That induces the moderate stress needed to gradually manage hull rot. Then hold that level for two weeks in early hull split. Don’t go back to full irrigation until harvest dry-down ahead of shaking.

“Hull split is within a month now. Kernels were filled as of last week in many orchards in the lower Sacramento Valley. Prepare for early hull split applications, which likely will begin in the last week of June. Don’t base your planning on early July for the start of spraying. We’ll know how the timing will run when we get closer. But it’s better to be prepared and wait a bit longer if necessary than to suddenly scramble to spray earlier than you expected.

“Navel orangeworm and peach twig borer degree-day totals are 810 and 1,116, respectively, at Nickels Soil Lab as of Thursday, June 4. These numbers use an early, mid-March, biofix.  

“It will be interesting to see if the second-generation pattern matches those biofix dates. Right now, the PTB moth patterns are not following what you would expect from a mid-March biofix, but I think widespread May sprays in this area may have reduced PTB moth populations, making moth catches harder to interpret over time.

“Walnut husk fly catches started earlier than normal this year. Typically, the timing is mid- to late June, but this year they began appearing in traps in early May. This year, those traps already should be up because of this early trend.”

 

Todd Fukuda, Weinberger and Associates, Hanford

“Almonds remain steady and show minimal plant bug damage. We continue to monitor but probably won’t need to spray anything until hull split. Timing for hull split appears to be on target compared to previous years. The last week of June would be the earliest we would spray, but most likely we’re looking at the first part of July.

“Mite populations remain low. We didn’t see any flare-ups from the first heat wave and hope this last round of heat didn’t flare populations, either. Late-season tissue diseases – rust and alternaria – also remain low.

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“In pistachio orchards, we’re finding a fair amount of chinch bugs. Fortunately, they are staying on the ground, not crawling up the tree’s crotch. We treated in the non-bearing trees to prevent damage.

“Alternaria is starting to pop up in male pistachio trees. Where trees have a history of alternaria, we’ll make three applications. We time those for the beginning of June, the end of June and the middle of July. If we’re not aggressive, alternaria will flare up right before harvest and cause leaves to start dropping.

“Processors encourage the use of AF36 in the nontoxic form to reduce levels of aflatoxin in pistachio orchards. During June and July, growers can spread AF36 along the drip hoses and with, the aid of irrigation, reduce aflatoxin in the soil.

“We continue to monitor for stink bug and plant bug in pistachios. However, we haven’t seen any damage that warrants treatment.”

 

Phoebe Gordon, Orchard Farm Advisor Madera and Merced Counties

“I’m seeing great almond fruit set all over the county. I’ve had limbs breaking in my almond variety trial and have heard of other instances of that, as well.

“It’s time to cut off nitrogen applications in almonds to reduce the severity of hull rot infections.

“We’ve had some hot weather across Madera County, and that can stress trees and accelerate insect development. Continue scouting for mites, but keep an eye out for beneficials while you’re at it. Beneficials do a phenomenal job of controlling mites as long as they haven’t been wiped out by early-season broad-spectrum insecticides.

“Pistachio kernel development has started in Madera County, and this is the stage at which pistachios demand the vast majority of the potassium they take up. Ideally, applications have already begun. Nitrogen applications should continue until harvest.

“Minimal bug activity has been reported in the area. Now that shells are hardening, we mostly just worry about feeding by the larger stink bugs and leaffooted bugs. Consider doing an ONFIT test if you’re concerned about botryosphaeria panicle and shoot blight causing blighted nuts at harvest.  Sample maturing fruit and send them to a lab. Results can guide treatment decisions.

“Let them add that we hope the Madera County Cooperative Extension office opens to the public again very soon.”

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