AgFax Tree Crops – Hot Weather In Almond Country Pushes Insects, Treatment Decisions

    Photo: Almond Board of California

    May sprays – where do they make sense in a year with plenty of mummies?


    Here is this week’s issue of AgFax Tree Crops.

    Our thanks to BASF and its California team for sponsoring this coverage.

    Owen Taylor, Editor


    Consistent heat settled over the Central Valley in the last week, with highs in the 90s on a wide basis. Some rain is in the forecast over the next weekend, so that may prompt some fungicide sprays.

    Moth activity has picked up. No peaks yet but the trend is in an upward direction. Depending on the crop and location, bug treatments are being made or are under consideration. Spider mites remain mostly quiet, based on this week’s reports, although brown almond mites more apparent in places.

    Bacterial blast losses are become more apparent now that nuts are sizing and filling. In certain blocks, it’s not a pretty sight. Otherwise, reports about crop potential remain upbeat.

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    Kris E. Tollerup, IPM Cooperative Extension Advisor, Kearney AREC, Parlier:

    We are well into the NOW flight and probably will see the peak here in 1 to 2 weeks, then counts will taper off a bit. Several folks were treating for leaffooted bugs.

    “This also is the point when people consider making a May spray. Typically, the university doesn’t recommend those unless a block is under tremendous pressure and has a plentiful amount of mummies. Unfortunately, mummy sanitation has been lax in places for whatever reason – whether due to the expense or because rain kept people from shaking. We also have cultivars that stick a little harder.

    “Whether to spray in May is still a block-by-block decision and not an automatic by-the-calendar treatment. If you do spray, at least consider something soft like a Bt. A veteran PCA said his clients run the gamut, from growers who have done an excellent job of mummy sanitation to those who didn’t sanitize at all. This guy has a history of actively avoiding May sprays but last year he felt like some were necessary. Again, he made the call on specific blocks.

    “Let me note, too, that we’ve made some upgrades to our UC pest management guidelines for NOW, and they’re worth reviewing as you decide whether or not to spray.

    “The subject has come up in recent reports about applying abamectin against leaffooted bugs. Keep in mind that it’s a contact material with these bugs. Immatures are easy to hit because they don’t fly away like adults might. On the other hand, if you find immatures, you’re already in trouble because the adults have been in place long enough to lay eggs and feed on the nuts.

    “One more consideration with abamectin is that it lacks residual activity on leaffooted bugs. Once the residue dries, there’s probably no further control. You’ll find a section on abamectin in our leaffooted bug guidelines.

    “Another option is a pyrethroid. It can be a useful tool but use it only when necessary. The last thing we want is to apply it so often that we select out resistant populations. If you find leaffooted bugs, make sure there’s actually a reason to treat.”

    Dan Prentice, Prentice Ag Consulting, Bakersfield:

    In almonds, we just finished our first fungicide spray. These have gone out in areas where we’ve tended to have alternaria. With some sprays, we included a miticide, depending on the needs of the specific block.

    “I’ve seen a little rust but it doesn’t seem to be taking off. I haven’t found any alternaria yet and mites are mostly in the background. It’s been warm this week, into the mid-90s. So, I’ve halfway expected an increase in mites but haven’t seen that yet. We’ll maybe start our second alternaria spray in the middle to latter part of next week. That will be on some of the earlier blocks.

    “In pistachios, a few guys have started with nutrient sprays and most will be making applications next week. In our beating trays we’re finding a few plant bugs, both large and small, and some stink bugs. In those locations, we’re including an insecticide with the nutrient spray. Mainly, these are green stink bugs and phytocoris. No leaffooted bugs have turned up, at least not in my pistachios, although we normally don’t see them in pistachios this early.

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    “I am finding an occasional leaffooted plant bug in almonds but haven’t treated any. They’re just random, with no damage. We treated some early on but leaffooted bugs have been pretty quiet since then.

    “Half of my tomatoes have been planted and the other half are going in next week. No worm trouble in the tomatoes but they’ve only been in the ground a couple of weeks. More worms than you’d expect are present in other crops, so we’re keeping a sharp eye out for them.”

    Franz Niederholzer, UC Farm Advisor, Sutter/Yuba Counties:

    It’s warm. My car’s thermometer puts it at 91 (late afternoon, 4/26), and that’s at least 10 degrees higher than what we expect here on an afternoon this late in April. The warmup came quickly and it’s been a little hard to adjust to it. Along with warmer days, temperatures at night have been in the mid to upper 50s and up to 60 for the low. That’s a big change from the mid-40s.

    “With this heat, insects are flying a lot, and counts jumped in about a week’s time. At the Nickels Soil Lab, we made our PTB biofix 7 to 10 days ago, around April 17. At first, they just kind of trickled in but the numbers have now jumped.

    “I’m still not sure about a biofix for NOW. The male trap counts have bounced around but our traps at Nickels haven’t seen any eggs yet. However, several PCAs said they were finding eggs. Differences may somewhat be related to how much people could sanitize trees.

    “No mites yet and no disease, either. No rain is in the forecast. The ground finally dried up enough that people are working fields and planting new orchards.”

    Aaron Beene, PCA, Simplot Grower Solutions, Merced:

    We’ve finally moved into warmer weather, and it’s been in the mid-90s the last few days (from 4/26). Cooler conditions are in the forecast next week, down to the low 80s with a chance of rain next weekend.

    “The NOW trap numbers are starting to go up pretty good and egg laying began just this week. Some guys will do that mummy spray timing on the first generation to try to minimize numbers at hull split. This is limited to blocks where growers couldn’t get in and shake trees or who had high damage last year.

    “Trees are pretty clean in terms of disease. I haven’t seen any rust yet. I know it’s a matter of time and we probably will detect some in the next 2 weeks. For right now, though, it’s holding. I’m seeing some symptoms of bacterial blast moving onto the leaves. It rained earlier in the month and blast spread from infected blooms to the leaves.

    “It can be mistaken for shot hole and some growers thought that’s what they were seeing. Because it’s bacterial, fungicides won’t help. But it’s a cool-weather disease and will cease to spread now that temperatures are hotter.

    “We’re coming into May, so we’ll be applying the last of our nitrogen. We usually shut it off around June 1 for hull-rot prevention. We have another 50 to 60 units remaining for May applications and we will evaluate the crop to determine how much we’ll finally need. Most of the drop has either happened or is under way, so we can make some informed decisions.

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    “Nuts are starting to fill. I still think that crop development is 1 to 2 weeks behind normal, but with warmer weather it should start catching up to a degree.

    “In walnuts, we’re catching some codling moths. Based on degree-day accumulations, the !A timing is lining up for the middle to latter part of next week. I usually wait for the 1B timing to spray. But with the chance for rain next weekend, we may go through with copper for walnut blight in earlier varieties and might include something to knock down codling moths.”

    Todd Fukuda, Weinberger and Associates, Hanford:

    With almonds, we’re kind of in ‘stand-down mode’. We’re irrigating, working on nutrition and waiting for the May sprays to come up. However, there’s no big rush to crank up the May sprays. At this point, we’re lining up equipment and chemicals but aren’t jumping into applications right away.

    “So far, I haven’t seen a whole lot of mite activity. In our Kern County blocks, we’re finding some brown almond mites. A little leaf stippling is apparent and we’re watching them closely, but populations so far are low.

    “With most of our almonds, the crop is set and looks really nice, with just a little drop. Sizes so far are nice.

    “In pistachios, we’re writing recs but are holding off until next week for the zinc/copper sprays. We do those when all the leaves are out and turning green, and we’ll include micronutrients. We’ll also do some permethrin applications where we’re beginning to see nuts hit by plant bugs. This is nothing widespread but in places we’re finding a little damage. We’re picking up both lygus and calocoris. A few phytocoris are in the trees, too, but nothing at a treatable level.

    “With this week’s heat wave, weeds are starting to dry up and insects will begin moving from the hills to the valley floor, then into the trees, and we’ll want to treat for that when necessary. Our pistachios range from some that are still pollenating to BB size and up to a half-inch. Those nuts that are BB sized and larger would be susceptible to plant bugs. Since we’re going across with nutrients, it seems prudent to also knock down some of this pressure where needed.”

    Gary Gliddon, PCA, Treevine Consulting, Modesto:

    People I’m working with this year fall into 2 categories – those hit by bacterial blast and those who weren’t. With the exception of a couple of older almond orchards, the damage was mainly in younger blocks. Those trees still have some nuts but by any measure it appears to be a poor crop.

    “Where growers weren’t hit by bacterial blast, the crop potential looks pretty good. I’m telling those growers that they have at least an average crop if not a little above average.

    “The only negative right now is blast damage and I can even find a little of it in some of the better orchards. No shot hole or spider mites. I’m seeing just minor instances of brown almond mites. Otherwise, we’re keeping fertilizer going and have started irrigating.

    “Like everyone else, I’m catching NOW moths. Counts in some of the male pheromone traps are really high, but in most cases, I’m not catching many females. I’m debating about spraying where mummy shaking didn’t go well. I know there’s some research to support that idea but it’s never seemed to help that much when I’ve tried it, whether that had to do with timing, coverage or something else.

    “I’ll probably stay with multiple sprays at hull split, although a couple of growers want to consider that treatment where more mummies are in the trees than they like to see. With hull-split timing I’m not as concerned about degree-day timing and can wait and see what the tree does.”

    More trees, more good news.
    Plenty of variables determine reserves. Recent auger evaluations by farm advisors have shown very different levels of soil moisture depletion between the east and west side of the valley. 
    Wide range of topics covering almonds and walnuts.
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