Shelling Out Useful, Real-World Almond Knowledge
As we continue to move into almond bloom, the time to start is now. Every month brings new needs and new possibilities to your orchard, so we’ve done our best to put together the following advice for your almonds.
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Maximizing Nitrogen Uptake Efficiency
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No one has to tell you that the fertilizer market in 2021 is extremely volatile and that means higher costs to almond growers for their fertilizer inputs. Where can cutbacks be made without sacrificing orchard health or productivity? What tools can Wilbur-Ellis bring to the table to maximize Nitrogen Uptake Efficiency (NUE)?
To begin with, it is important that nitrogen applications be timed to coincide with nitrogen demand and that means more or less spoon-feeding throughout the season to maximize NUE. It makes no sense to make a large slug in a single application early in the season as one of our young CCAs informed me a local consultant is advising (150 lbs. N per acre mid-March). WRONG! The general rule of thumb from the UC is as follows:
- 20% February-March
- 30% April
- 30% May
- 20% September-early October
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Now, having said that, where can nitrogen inputs be cut back? First, refer to last year's July leaf analysis results. If summer leaf N was 2.5% or greater, then you SHOULD be cutting back on your nitrogen application rates. Leaf levels greater than 2.5% have been associated with increased incidence and severity of hull rot.
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If this year’s summer leaf N levels are 2.5% or greater, then you do NOT need a post-harvest nitrogen application. If you have 16-20" or more of new growth, then your trees are well supplied with nitrogen. Other than light, frequent nitrogen applications timed to drop demand, what else can be done to maximize NUE?
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NDURE DCD. We covered NDURE DCD in last April's newsletter (link here) but we will discuss the product again. NDURE DCD is a proven nitrogen stabilizer containing the powerful nitrification inhibitor DCD (dicyandiamide, CAS 461-58-5).
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NDURE DCD mixed into liquid UAN or urea blends slows the conversion of ammonium to nitrate. This leaves a greater percentage of applied N in the ammonium form. By keeping nitrogen in the ammonium form we can reduce losses of nitrate due to leaching and denitrification.
Leaching losses occur when water in excess of crop ETc moves through the root zone. Nitrate is very mobile in the soil and can be leached out of the root zone. In contrast, ammonium is immobile in soils and does not leach.
Denitrification occurs when soils become anaerobic and soil bacteria rob oxygen from nitrate molecules in step-wise reduction that results in the formation of gaseous forms of nitrogen that can be lost to the atmosphere. Because ammonium NH4+ does not contain oxygen, it is not subjected to denitrification losses.
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Losses from denitrification can be very significant if soils remain saturated for any length of time. For example, at soil temperatures of 75-85OF up to 60% of nitrate-nitrogen may be lost from soils saturated for a period lasting 3 days! This may be from cumulative periods of soil saturation or a single 3-day event.
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NDURE DCD can be added to UAN at the recommended rate of 4 quarts per ton or can be purchased as a premix as Till-IT Fluid Carbon 27-0-0 with NDURE DCD or Till-It Fluid Carb S 26-0-0-3S with NDURE DCD. If you want to take a deeper dive into NDURE DCD and its use on almonds, then please follow the link to last year’s April Newsletter above.
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Carl Bruice, Wilbur-Ellis National Nutrition Technical Manager
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Planning For Your 2021 NOW Control Program with Alternative Approaches
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Naval Orange Worm (NOW) continues to be one of the toughest pests to control in almonds. With the difficulty of controlling this pest, building a program with an integrated approach is the best way to combat NOW populations throughout the season. These approaches include sanitation, the use of synthetic insecticides, mating disruption, and biological control agents.
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Though synthetic options for controlling NOW may be shrinking, the alternative options are ever-growing. These alternative options can enhance NOW control and preserve the use of synthetic chemistries.
Sanitation: The First Line of Defense
NOW overwinters as larvae in the mummy nuts of almonds, pistachios, and walnuts. For almonds, it is recommended to mummy shake or pole these mummy nuts prior to bud swell. Once removed from the tree, these nuts should be destroyed by means of discing or flail mowing prior to March 15th. In the south-central San Joaquin Valley, it is recommended to have less than 0.2 nuts per tree versus the northern San Joaquin and Sacramento Valley which has a threshold of fewer than 2 mummies per tree. Why the difference? The further south, the greater accumulation of growing degree days.
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The Math Behind Mummies
With every mummy there is potential for it to be infested with NOW. This potential population can grow rather quickly considering a single female can lay around 85 eggs (1). If 50% of the eggs laid by a female NOW were also female, within 3 generations 1 NOW could turn into 159,014 NOWs without proper control methods. The 0.2 threshold comes from a study done by a partnership between Paramount and Joel Seigel. This highlights the number of mummies left in the tree with the correlating damage (2).
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Make Your May Spray and Mummy Spray
What do you do if sanitation practices didn’t meet the 0.2 recommended standard? Budget for a mummy sprays prior to the first flight.
Degree day accumulation begins January 1st and is dependent on temperatures between 55 to 94°F. Typically the first flight will begin around April 25th to May 1st and treatment for this timing is commonly known as the “May Spray”. The focal point of this May Spray should be covering the Mummies and choosing a material that will have an ovicidal activity or target feeding larvae. This application should be made by May 1st.
Ask your PCA how the degree days are tracking this season to understand how this year compares to historical years. If you want to see where the degree days are for yourself, click here and enter the location information you want to look at.
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Mating Disruption
With reduced synthetic chemical options and very little noise coming from the pipeline, it’s imperative that we preserve the tools we have by using alternative approaches such as mating disruption. This alleviates pressure from synthetic chemistries by scrambling male NOWs with synthetic pheromones, rendering them incapable of finding female NOWs and mating.
- Puffers dispensed on a grid system, puffers alone have been shown to reduce naval orangeworm damage by 37% in a study published in 2008 (3). Companies like Suterra claim as much as a 50% reduction in damage with the use of puffers. These systems only need to be dispensed once a year. They are hung in trees and disperse aerosol pheromones at programmed times. With this dispensing mechanism, the rate of pheromone dispensed is consistent throughout the season.
- Flowable pheromones were released into the marketplace a few years ago. This technology offers convenience. It can be tank-mixed with other agrichemicals and can be applied via a foliar application. The residual on this material is around 30 days. One benefit these pheromones hold is the 24-hour dispensing of these pheromones.
- Contact your PCA or local Suterra representative to discuss tank-mix compatibility.
An organically accepted option for mating disruption would be Cidetrack by Trece. At 15-28 dispensers per acre, this option offers a season-long option for mating disruption. These dispensers disburse pheromones for up to 6 months.
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Alternative Control Options
A new emerging form of treatment utilizes biological agents to aid in control of NOW.
Spear-Lep coupled with a Bt product has been shown to greatly reduce NOW populations while having little to no impact on other beneficial populations. This product utilizes GS-OMEGA/ KAPPA-HXTX-HV1A, a peptide found in spider venom.
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After application, the Spear-Lep works through being consumed by the NOW larvae. The Bt, which is specific for lepidopteran pests, helps the Spear-Lep get past the digestive system. From there, it targets the nervous system. This product offers a unique mode of action, Group 32, acting as a great rotational partner with other chemistries in your NOW program. You can find more information about this product here.
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Creating an IPM Strategy
Ask your PCA how you can create an IPM strategy for combatting NOW by using multiple approaches. Always read and follow the labels. Discuss best use practices for each strategy with your PCA to ensure proper application and achieve optimum results.
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Rebekah Arnold, Wilbur-Ellis Sales Trainee
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References
Haviland, David. 2017. Navel Orangeworm Biology and Management. American Pistachio Growers Conference
Bradley S. Higbee, Charles S. Burks, 2008. Effects of Mating Disruption Treatments on Navel Orangeworm (Lepidoptera: Pyralidae) Sexual Communication and Damage in Almonds and Pistachios. Journal of Economic Entomology, Volume 101, Issue 5, 1 October 2008, Pages 1633–1642
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Irrigation Water Management for Almonds
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Water is a critical part of the potential success of any farming operation no matter where you are located. Growers are constantly faced with making decisions such as:
- When do I start my first irrigation of the season?
- How often should I irrigate?
- How long should I irrigate?
- Am I irrigating too much? Not enough?
- Am I stressing my crop?
- When is it ok to stop irrigating after the crop is off?
- What tools are available to help me?
The Wilbur-Ellis teams understand the stress, frustration, and moving targets around a successful IWM program and have invested in tools and resources to help assist our growers throughout the season.
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Soil Moisture Monitoring is one way to address Irrigation water management. Understanding when the crop is using soil moisture, how much water is available, irrigation frequency, and duration can all be addressed through a successful soil moisture telemetry program. Wilbur Ellis offers a soil moisture probe lease program with a user-friendly grower dashboard and mobile app Through Probe Schedule software. The Soil Moisture Lease program takes the constant evolving equipment stress off of the grower and allows them to focus on impactful irrigation program management at the farm.
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We not only offer our own probes but, in most cases, can adapt to existing telemetry and probes on the farm through Probe Schedule Software. This lease program is currently offered throughout the Western Region with a per-site fee.
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Irrigation Scheduling Services is another service offered to our growers. With this program, a grower can expect a full field irrigation distribution audit of the blocks in the program, custom tailored weekly emailed recommendations which include; Weekly plant stress readings (Stem Water Potential), soil moisture conditions and runtime recommendations based on replacement ET. The grower feedback on this program has been extremely positive and has shown to reduce drastic swings in irrigation protocol which in turn reduce pest and disease pressure and can increase plant health, crop quality and yield. This program is currently offered in the Northern Sacramento Valley on a per acre fee and will be expanding with future grower interest.
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Matt Maloney, Wilbur-Ellis Field Technology Manager
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A True Problem: Stink Bug & Leaffooted Plant Bug
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Two true bugs that are a problem in almond orchards in the San Joaquin Valley are the Green Stink Bug and the Leaf Footed Plant Bug. Both insects can cause damage to the crop that can result in economical loss to the grower. The Green Stink bug is the most common stink bug found in almonds.
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It is a bug that has a shield-looking body, has 6 legs, and a yellow line outlining the shape of the bug. Nymphs are black but as it develops and grows the green color starts to be dominant. Young adults turn green and have a shiny coat, but at that stage, the stink bug lack wings. Adults are more of solid green and the wings are developed.
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The females tend to be larger than the males and the female tend to lay their eggs near the almond hull. The eggs are barrel-shaped and have a ring on the upper portion of the egg. The leaf footed plant bug’s most important description is that it that the hind legs resemble a leaf. The leaf footed bug can also be identified by the horizontal zig-zag line across the back, and the two spots present in the upper portion of the back. The leaf footed bug is a brown/black color and has two long antennas, and it can measure up to 1 inch in length. The way that the Leaf footed bug lay their eggs, is unique.
The eggs are laid in a line or strand, and they are usually found on almonds hulls. Once the eggs have hatch it is important to identify the nymphs. The nymphs have a red body with black legs and 2 antennas are present. the leaf footed bugs resemble the looks of a katydid nymph, but the katydid is black and has stripes on the antenna. The leaf footed bug is red, and the antennas are a solid color. As adults both the leaf footed bug and the stink bug cause similar damage to the almonds through the long mouthparts piercing through the hull and damaging the embryo/almond.
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The Damage Caused
The green stink bug (Acrostenum Hilare) damages the almond by injecting an enzyme that liquefies the source of food that it will be feeding on, making it easier to travel up the needle-shaped feeding mouthpiece it has. The fruit then releases gummosis that can be seen outside the hull. The Stink bug usually pierces the hull multiple times and the gummosis is shorter but more frequent on almonds. Multiple feeding injuries can still cause the almond to be aborted even if the damage did not reach the kernel. Leaf footed bugs on the other hand will pierce the almond and leave a gummosis injury longer than that of a stink bug. Both damages can reduce the quality of the fruit, in worse cases, the almond will be aborted because of the damage. The time window for the damage for stink bugs is shorter than that of a leaf footed plant bug. The reason behind that is because the mouth part of a leaf footed plant bug is longer than the stink bug. Once the almond and the hull reach a certain size, the feeding mouthpiece is not long enough to penetrate through the hull and damaging the embryo.
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The leaf footed plant bug (leptoglossus clypealis) damage is very similar to the stink bug but the window for damage is longer, for the same reason, it just happens to be that the leaf footed plant bug mouthpiece is longer and can pierce the almond embryo. ideally, we would like to find the pest before it has caused any damage to the fruit, but that can be difficult with the leaf footed plant bug and the stink bug.
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Scouting Tips
Leaf footed plant bug scouting should start in March when the temperatures begin to rise. The scouting for damaged fruit should continue to post-harvest and into winter. Finding evidence of leaf footed plant bugs in the fall can increase the possibility of an insecticide mixed with the winter oil spray application. Both bugs have a stealth movement meaning that when they are approached by a person, the bugs tend to hide behind leaves, making it difficult to spot. The leaf footed bug likes to stay high on the tree and can be difficult to be seen. Sometimes the only indicator for us that leaf footed bug is present is by the piercing damage on fruit, or by aborded nuts in the ground. waiting to see nuts on the ground might not be as effective because it would mean that the leaf footed bug has been feeding there for approximately 1 week.
Stink bugs can be difficult because of the color they have, allowing the stink bug to camouflage with the leaves. Scouting for stink bugs can begin in the winter because the green stink bug overwinters in almond fields. Continue scouting until late summer that is usually when the shell is hard enough to prevent the penetration to the almond. The most susceptible varieties for stink bugs are the soft-shell varieties including Monterey, Fritz, Sonora, Aldrich.
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Approaching the Problem
Currently, there is no threshold set for leaf footed or stink bugs. If damage levels are high and potential economic loss is possible, there are insecticides that can be used to reduce the population. The decision for treatment and timing is based on the PCA and the grower. For treatment options and solutions please consult your PCA.
Alfredo Aguilar, Wilbur-Ellis Sales Trainee
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TO LEARN MORE:
To learn more about which products are right for you, visit almonds.wilburellis.com, or contact your local Wilbur-Ellis representative today.
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