California Almonds – Mites, Insects Stirring After Heat Wave – AgFax Tree Crops


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    Owen Taylor, Editor


    As expected, insect and mite activity have picked up to varying degrees after the summer’s first real stretch of intense heat. In almonds, spider mites are being treated in places in the lower San Joaquin Valley. With most pests, though, people in the field are monitoring populations and trap counts, hoping they can hold off until hull-split sprays start.

    Rust has become more obvious in scattered orchards in the southern SJV. Alternaria also is showing up in that part of our coverage area.

    Brown marmorated stink bugs recently hit almonds and peaches on a limited basis in the northern SJV. See Jhalendra Rijal’s comments, which include a link to more info on this relatively new pest.

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    Dale Deshane, PCA, Supervised Control, Bakersfield:

    “Mites really took off in a few blocks here and there and we’ll spray before hull split. They’re moving up the tree and webbing is apparent. With this heat, we don’t think we can wait until the regular hull-split spray.

    “I imagine that we’ll make NOW treatments toward the end of June in early blocks in the southern end of the valley. These will be edge treatments. A few growers in that part of Kern County always seem to get high percentages of early splitting on edges, and we try to time a treatment for that part of the blocks. That will likely be in the last week of the month, then we’ll wait a few days and do the whole hull-split spray.

    “Alternaria is progressively getting worse in blocks with a bad history of it. We’re just finishing our third spray for alternaria in those orchards and we’ll probably make one more fungicide application with the hull split spray.

    “With this heat, rust is picking up in almonds. We had been finding specks of rust in places but now we’re seeing leaves covered in it. Oddly, scab is the one thing we haven’t detected. Typically, it turns up first in hard shells, especially in Butte, but we’re not finding any right now (6/14).

    “Stink bugs seem to have settled down. For quite a while, immatures and eggs were increasing. They haven’t disappeared in almonds but activity has decreased in about the last 10 days

    “In pistachios, we started finding the first alternaria this week on trees in two different areas. In both cases, those growers had it before, but it’s interesting that it showed up in both locations at the same time.

    “Plant bugs have been kind of quiet in pistachios. We’re finding a little phytocoris and other small bugs but nothing has required a treatment recently. We may do another bug spray in the last week of June, which will include the second alternaria spray.

    “In cotton, lygus came on about as expected, considering all the rain. Last week, we sprayed 99% of our fields one time but we’ve also had to make multiple applications since then on certain ranches. With one grower, we’ve now treated 3 times. He has about 400 acres toward Buttonwillow and we couldn’t kill enough lygus with the first treatment to matter.

    “Counts were running 25 to 30. The cotton is in a desert area and hay cutting in nearby fields had been held up by the rain, which gave lygus and stink bugs extra time to build. When the hay was cut, the lygus poured out.

    “Three days after the first spray, we treated again and knocked the counts down to 15, then sprayed yesterday, which was the third application in a 10-day period. We took a quick look this morning and the counts were down to 2 or 3.

    “We resprayed another grower’s cotton this morning. This is high pressure, to the point that we can’t find squares on some plants that are at 10 to 12 nodes. Overall, square retention is poor on almost all of our fields at this time.

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    “No aphids or mites are apparent in cotton but they’ll likely develop after the spraying. We just started finding a little mite activity in early corn. Conditions were cool enough in May that they couldn’t get going, and populations have been pretty light for this time of the year. However, with this heat we could expect them to flare up.

    “Tomatoes were doing really well until that last round of storms hit. Hard rains fell, with hail scattered around. We’re now finding bacterial speck in places. Mildew isn’t exploding in tomatoes but we’re detecting a little more, even though we’ve been treating more than usual. We kept applying sulfur but then it rained and washed it off.

    “I’m treating the early tomatoes for worms and will include another mildew spray. Those fields are probably 3 weeks from harvest.

    “Alfalfa is still clean. A couple of our clients are trying hemp. This is a huge learning experience for all of us. It’s been hot this week and the high hit 111 on Tuesday. The hemp kind of buckled up.”

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

    “Things have warmed up and trees need water. We’re about a month away from hull split sprays. It’s nice today (6/14) after those 100-plus highs and warm nights on Tuesday through Thursday. It’s supposed to warm up again on Sunday and Monday, so we’re definitely into summer.

    “These conditions can drive spider mites, so we need to closely check for them. In walnuts, it’s time for husk fly traps to go up.”

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

    “This weather with triple-digit highs most of the week has been torture, especially after mild conditions in the spring and early summer. So far, though, spider mites have been pretty quiet, just mild populations in places.

    “We don’t see a reason to go in with a miticide now (6/14) but we are closely watching them. If we have to treat, we will, but I hope we can hold off treatments until hull split.

    “NOW counts are bumping up a little. It’s nothing terrible but I assume another flight will kick off soon. We’re planning trials in both almonds and pistachios with that new flowable mating disruption product, so we’ll see how that goes. We’re trying to time that with the next flight and two weeks before hull split.

    “In pistachios, we’re also watching trap counts and are checking for citrus flat mites – it’s that time of the year. Today, we began finding false chinch bugs in younger trees and we’re starting to spray in places. They’re spotty but can be devastating in young trees, given the chance. We’ll have to be extra diligent over the next 30 days. If the usual pattern holds, false chinch bugs will cycle out after that.

    “A little nut fill is under way in pistachios, so we’re paying close attention to irrigation schedules and will bump up the water. Also, the June fertilizer shot is going out now.

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    “In walnuts, the second-generation codling moth flight is in progress we will start our 2A applications toward the end of next week. Ahead of the 2A spray, we’re watching for mites and will include a miticide if and where it’s necessary.

    “In citrus, we’re about through with the thrips season and have been keeping a close watch for citrus flat mites in lemons. They tend to feed where thrips damage occurred.

    “In pecans, we’re on round one with our aphid sprays. Pecans are kind of a zinc hog, so we included it in the tank. We’re actively watering pecans now.”

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

    “The high topped 100 for several days last week, so people are irrigating to try to keep the trees wet.

    “Last week was the first week I’ve seen any spider mites surface this year. They’re just starting and I let my clients know that mites are present and be prepared to spray if populations quickly jump. I’m hoping we can hold off applying a miticide until hull split. But considering this heat, we need to be cautious with mites.

    “In walnuts, I’m seeing walnut aphid populations building in places, but they’re not nearly at treatment level yet. European red mites are showing up a little and I’m also noticing a bit of spider mites in walnuts.

    “With codling moths, we have set a second-generation biofix based on trap catches and accumulated degree days from our first biofix. Treatment timing for the 2A flight should land in the second half of next week. Trap catches have been fairly low and if they do not increase substantially, we will wait and treat at the 2B timing.”

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

    “Weather was definitely hot last week and into this week, and we will move back into the upper 90s to 100s starting on Sunday. So, we can generally expect an increase in insect and mite activity.

    “Despite the cooler spring, NOW don’t seem to have been affected much. In the orchards we are monitoring, the weekly average moth count in pheromone traps has been running from 15 to 20 moths. That was the case last week and again this week. Egg counts also were high in some traps. I certainly expect counts to increase in the coming weeks.

    “In walnuts, PCAs continue to tell me that codling moth pressure is low this year in the northern San Joaquin Valley, although that can vary from orchard to orchard. In the moth traps we monitor in the Modesto area, the counts increased and I set the biofix for the second codling moth generation on June 11. Figuring 300 degree days from the biofix, the projected insecticide timing in those orchards would be around June 20.

    “We are catching brown marmorated stink bugs in both almond and peach orchards in the northern SJV. About 2 weeks ago, one orchard developed a pretty significant BMSB infestation and with very high crop loss, especially in border areas 4 to 6 rows into the block.

    “Many people are new to BMSB and the damage the insect can cause. I posted an article on identifying this invasive insect and it damage. People in the field might want to bookmark it on their phones for quick reference this summer.”

    Early hull split, when the hull begins to open at the suture, is a don’t-want-to-miss timing in almond production.
    The sweet, edible almonds we enjoy today are a far cry from their bitter wild ancestors thanks to a point mutation in the genes.
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