Almonds – California – Not Too Early To Think About Hull Split – AgFax

A storm rolls through the upper San Joaquin Valley on May 18, 2020. Photo: Aaron Heinrich, Independent Crop Advisor, AgriWest, Inc., Escalon

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Owen Taylor, Editor
Jenny Holtermann, Contributing Editor

OVERVIEW

The almond crop continues to look promising as we head towards June. At this point, the very earliest hull splitting for 2020 is about five weeks away.

Rain earlier in the week reached most of our coverage area. Fungicides have been going out.

Heavy hail fell in parts of the upper San Joaquin Valley.

Fertilizer applications are winding down in almonds.

Stink bug monitoring and/or active populations were noted by all of our contacts this week.

Spider mites are more apparent in some orchards.

In walnuts, the first-generation codling moth flight has concluded or is cycling through, and the focus now shifts to preparing for the second flight.

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CROP REPORTS

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

“Rain early in the week fell mostly on the east side of our area. Terra Bella received half an inch and Visalia picked up an inch, but minimal amounts fell on the west side.

“Almond growers are trying to finish the final fertilizer application by June 1. We are working towards the end of June or the first part of July for hull split to begin.

“Growers are pushing to keep up with irrigation demand. It has been mostly warm, and the trees are demanding water as they finish sizing up nuts. Nonpareils are 60% hardened now as they finish filling and move past the gel stage.

“We see hot spots for mites in a particular field, with mites scattered consistently throughout the orchard. We plan to knock out eggs and females with an insecticide that won’t hurt beneficials. Sixspotted thrips populations are present and working on mites, as well.

“False chinch bug is starting to show up in young almond plantings. They can move onto leaves and put off an enzyme that can kill the trees. It only has one generation, which hatched in mid-May. It can last a few weeks, and they tend to be more common in pistachios. However, they are detrimental to young almond plantings, as well.

“We finished spot spraying for navel orangeworm to help where populations were higher, mostly in areas with less effective sanitation practices.

“In pistachios, we’re finishing the second fertilizer application. We have another month until nut fill, so growers are staying on top of irrigation.

“We are finding sporadic populations of leaffooted plant bugs in pistachios, but shells are starting to harden, so those bugs are less damaging now.

“In areas on the east side that received more rain, we are spraying for botryosphaeria and alternaria in places with a history of problems. Last week, we also began spraying for mealybug where it was needed, and our timing right now coincides with the crawler stage. The chemistry we’re selecting depends on the degree of damage we saw last year.

“In walnuts, nutrient management remains essential. Ivanhoe blocks are more susceptible to walnut blight, and treatment were necessary ahead of the rain.

“Codling moth 1A and 1B flights have cycled through, and we will focus our treatment efforts on the 2A flight towards the middle of June.”

 

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

“Lightning and thunder rolled through San Joaquin County during periods on Monday (5/18). The rain was sporadic, from half an inch in places to only traces in surrounding areas.

“Pea-size hail hit pockets, as well, but luckily only lasted for ten minutes. Significant amounts of hail blanketed the ground in areas just north of Escalon, enough that it briefly caused slick road conditions.

“A few walnut orchards show hail injury on the nuts, although it didn’t appear to cause significant economic loss where we checked. We haven’t found or heard of any hail damage in almonds, although that’s not to say some didn’t happen.

“Almond growers are wrapping up fertilizer with that final nitrogen application. The goal is to finalize nitrogen by June 1.

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“A small number of fungicide applications went out before the rain. Alternaria, rust and anthracnose can be a concern in blocks with a history of these diseases. We’re close to the tail end of treatment timing effectiveness with these diseases, especially with warm weather in the forecast since their last treatments. Growers in the area were applying fungicides this week after the rain. However, effectiveness may be questionable.

“Monitoring continues for stink bug and leaffooted plant bug, and spot treatments occurred in areas with high pressure. It’s important to remember these hot-spot locations when scouting and planning treatments next year and beyond.

“We are putting together our hull split programs with an emphasis on effectively rotating chemistry. We are tracking navel orangeworm flight activity towards week 27 or that last week of June.

almond-trees-storm-aaron-heinrich-20200518[1]_1573518.jpg
A storm rolls through the upper San Joaquin Valley on May 18, 2020. Photo: Aaron Heinrich, Independent Crop Advisor, AgriWest, Inc., Escalon

“In walnuts, we’re between codling moth flights. Many traps had a fair amount of 1A activity, while others had nothing. For growers, that underscores the important of placing traps in all their orchards.

“Right now, traps are reasonably quiet as we watch for 1B activity, which tends to occur between 600- and 700-degree days from the biofix. We’re treating in places, based on a field’s history, how significant the 1A damage turned out to be and how heavy those first-generations flights were in a specific walnut orchard.

“Next week, we will begin hanging husk fly traps and then begin monitoring those on June 1.

“We are easily finding walnut aphid in nearly every block we are scouting. Right now, we see low numbers, but they are present, so we’ll watch for rapid increases that would warrant treatments.

“We are just starting to see spider mites in low numbers. We treated a few blocks for European red mites in an early stage. We are monitoring a few more blocks that could justify treatments if the numbers continue to build. Double-sided sticky tape monitoring for scale crawlers showed a significant amount of walnut scale and frosted scale this week. Next week, we plan to treat a few of those blocks at the crawler stage.

“Overall, we see more scale pressure this year than in previous years. This possibly is due to more reliance on mating disruption, which results in fewer of the worm applications that previously would have provided scale control. Without treatments, scale pressure leaves opening sites for secondary infections, such as botryosphaeria.”

 

Dan Prentice, Prentice Ag Consulting, Bakersfield

“A slight shower fell Monday morning (5/18), and then another developed that evening and it was just enough to settle the dust in our area.

“In several places across Kern County, we are fighting rust as well as alternaria. The tissue diseases showed up early and remain significant concerns as we head into the final growing stages. Growers are spraying in an attempt to keep leaves on the trees until harvest. The majority of growers have been playing catch up, trying to bring it under control. 

“Insects have been quiet lately, with no plant bug issues since we treated in the middle of May.

“Spider mites are starting to show up along field edges. We do expect that mite pressure will increase as temperatures heat up next week, and we will closely monitor to see how quickly populations build. We’re less than five weeks away from that first planned hull-split spray at the end of June, and growers would prefer not applying a miticide before then.

“Traces of alternaria began to show in spots where pressure was evident in previous years. Mealybug treatments started this week as populations increased.”

 

Jhalendra Rijal, Area IPM Advisor, Northern San Joaquin Valley

“Monday’s rainstorm brought a quarter of an inch to the Modesto area and higher amounts in the northern part of the valley. The main issue was with cherries as they finish ripening now, and they tend to split after a rain. Rain favors the growth of spotted wing drosophila populations, too, which could lead to control measures in areas with more rainfall.

“Navel orangeworm eggs are present in traps. There’s always activity, although sometimes it’s sporadic. Yesterday, we counted 50-plus eggs in one specific trap. Peak adult trap counts usually occur at the end of April through the first week of May. Growers who are diligent with winter sanitation can limit their May spray programs and focus more on hull split programs. Infrequent May sprays have been made in the area, mostly where growers already were going to treat for peach twig borer.

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“Plant bug and leaffooted bug have been more of a concern than in past years. Brown marmorated stink bug (BMSB) also is present in the area and is causing damage in a few orchards. These bugs enter orchards in April and can cause nut abortion in the spring. BMSB tends to venture into other crops, such as peaches, but can hang around in almonds through July or even into August.

“Green stink bug, redshouldered stink bug and consperse stink bug move into orchards around June and are more of an issue later in the season. Closely watch for them. These stink bugs aren’t widespread and do not cause economic damage unless very high populations develop in orchards.

“Mite pressure has been minimal here in almonds over the last couple of years during the spring and early summer. They tend to be more of an issue later in the season during hull split. Any populations would have been wiped out with the rain earlier in the week. Once temperatures begin to rise next week, it will take another week for populations to rebuild in weaker areas. I would expect less pressure in fields with continuous irrigation or higher moisture levels. Dry and dusty environments will be more prone to mite.

“Sixspotted thrips are often controlling mite populations, and we are starting to use yellow sticky cards to monitor thrips presence throughout fields. Avoid treating spider mites if thrips populations are still holding back mite pressure. If you treat, consider a material that helps maintain beneficial populations.

“In walnuts, people are reporting more codling moth activity. Moths are consistently turning up in traps, with some counts running above 100. We expect to see populations eb and flow. Every few years, codling moth populations increase after being down the last several years.

“Husk fly traps will begin going in place in early June, and we will monitor those traps through August and into September before harvest.

“Pacific flat-headed borer adult activity starts around this time of the year in walnuts. The beetle will place its eggs on trunks of younger trees. When the larvae begin coming out, they initially feed on the inside of the bark of the branches, then later move into the heartwood. The younger trees will wilt and often die from the damage.

“Borer issues have increased in several orchards over the last couple of years, mainly in the northern San Joaquin Valley. The larvae are attracted to bark cracks, wounds and sunburned areas. It’s essential to paint the trunks for sunburnt to prevent damage. We see damage on mature trees as well, but the most significant economic loss occurs on younger trees.”

  

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

“The weather has been cooler than average for the last ten days, with significant rainfall in many valley locations. Chico on the east side of the valley received 1.5-plus inches this week, while significantly less fell on the west side. At the Nickels Soil Lab, we recorded about a quarter of an inch in that same period.

“Cool and sometimes wet weather slowed insect buildup but also raised the chance of disease infections in all tree crops, but I haven’t heard of or seen any new outbreaks.

“Temperatures will start ramping up over the weekend, with near-record highs in the low 100s by Memorial Day and into mid-week. After that, though, temperatures are supposed to fall into the 80s.

“Temperature swings like that help promote biocontrol of spider mites. The heat pushes spider mite populations up. Then when it cools off, the beneficials – if they are present and in enough numbers – can catch up with the mites and keep them in check.

“Almonds continue into kernel fill. Growers are finishing nitrogen applications and keeping up with irrigation. The last potassium applications can be stretched into June if needed.

“Navel orangeworm trap counts decreased this week with the cooler weather. Since the biofixes at Nickels, the navel orangeworm degree-day accumulation is at 520 DD and the peach twig borer DD accumulation is at 765 DD. Biofixes for both NOW and PTB were set just before March 15, the earliest I can remember.

“At Nickels, we are finding some codling moths, but only a few walnut orchards are in that area. Husk fly traps go up in less than two weeks.

“The first walnut nitrogen applications should go out soon if they haven’t already started. The walnut crop that I have seen looks strong.”

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