WCN, Author at West Coast Nut

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Maximizing Hull Quality to Add Value for Growers

Conditioning windrows before they are picked up from the orchard floor can bring added value almond growers.

Mike Kelley, president and CEO of Central California Almond Growers Association, said like many other California almond hulling and shelling operations, CCAGA is now charging on a delivered weight basis, an incentive for growers to send cleaner loads to hullers and shellers.

Cleaner product delivered to the processor not only saves freight costs, but also helps improve almond hull feed quality for dairies, the largest market for this almond by-product. Growers who use a conditioner to remove sticks, dirt and other orchard debris from the windrows deliver a cleaner product, enabling hullers and shellers to deliver a higher-quality dairy feed.

Kelley said it is important to maintain quality of almond hulls delivered to dairies as it maximizes value for the grower. Almond hulls for dairy feed cannot exceed 15% crude fiber, 13% moisture and 9% ash. Almond hull and shell is defined as more than 15% but less than 29% crude fiber. Sticks and shells in the samples add to the fiber content of the samples, but add no nutritional value, lowering the value of the product.

“We’re told the cows push the sticks aside, but dairymen don’t want to pay for the extra weight they add to the product,” Kelley said.

Kelley said processors work to meet CDFA standards for almond hulls, recognizing different varieties of almonds have different hull fiber content. Nonpareil typically has 11% to 12% fiber while pollinator varieties have a higher percentage. Varieties can be blended to keep crude fiber content below 15%, but it is not always easy. Kelley said they sample fiber levels in the hull line to determine the blend.

“We try to go lower to give us a cushion,” he said.

Central California Almond Growers Association is a cooperative and sells hulls to a group of dairies. To preserve a good relationship with the producers, Kelley said CCAGA strives to deliver a quality product.

Dairy nutrition consultant Jed Asmus noted that the purest form of almond hulls, those with the least amount of shell, will demand the most value and could demand a higher premium. Contamination of hulls with shell reduces the feed value through dilution and reduces the value of the product.

Incentives Available for Mating Disruption Adoption

Tree nut growers have many choices in mating disruption products for navel orangeworm control in their orchards, and the Natural Resource Conservation Service’s (NRCS) 595 program offers financial incentives to adopt mating disruption and use it in an integrated management plan.

The conservation pest management system integrates mating disruption products with orchard sanitation and mummy nut removal, extra shake and pole removal, monitoring and chemical control timing to lower NOW pressure. Mating disruption products include lures and pheromone sprays. Insecticide timing includes traps and scouting. Early harvest is another component of the program. NRCS does not provide pest management recommendations.

Agronomist Karen Lowell with NRCS said in a presentation at The Almond Conference that implementation of a grower’s conservation pest management system does not require changes in their current chemical control strategies for pests and diseases. Monitoring for pests and disease is the foundation of the program. NRCS encourages following UC IPM guidelines.

Documentation required in the NRCS 595 program includes date of mummy nuts counted and average count of mummies over a minimum of 20 trees. If a grower is unable to reach the threshold, they must provide an invoice showing a minimum of $200 per acre invested in poling crew labor in an attempt to reach the threshold.

Other documentation needed to participate in the program includes a list of types of traps used for NOW and the date placed in the orchard, monitoring results for NOW, harvest date and records of pest or pest damage noted in the harvest sample. Growers must also provide a list of the pesticides, including the name, rate used and application date of the mating disruption product used on the contracted acreage.

Additional cultural practices used to avoid pesticide impact on sensitive areas near an orchard must include a map and description of the practice.

Lowell said tree nut growers can get started by contacting their NRCS county office to create a conservation plan for their orchards. Financial assistance is available through several Farm Bill funded programs. The NRCS planner can provide details about the programs. Although the program is aimed at navel orangeworm control, it may also be used to address a different pest or disease issue in another crop.

Improved Awareness of Flat-Headed Borer Infestation

It is not so much that flat-headed borer (FHB) infestations in California walnut orchards are increasing; rather, growers are now more aware of this pest and the damage it can cause, particularly in young trees.

Three years ago, when signs of FHB infestations began to appear in San Joaquin and Stanislaus counties, UCCE IPM Specialist Jhalendra Rijal heard from growers about flagged branches, dead twigs and canker-like symptoms on tree trunks. Since that time, infestations of this pest were reported in northern and southern walnut growing regions of the state. Reports have increased, Rijal said, as more growers recognized signs of infestations.

Flat-headed borer is a larval stage of one specialized group of beetles. The name ‘flatheaded’ comes from the enlarged and flattened shape just behind the head in the larval stage. Adult FHB are a half-inch to three-quarters of an inch long with a wedge-shaped body. They lay eggs in weakened portions of bark cracks. Newly hatched larvae bore into wood and feed on the cambium layer. The larvae overwinter in the pre-pupal stage and emerge as adults in the spring or early summer, leaving ‘D’-shaped exit holes in the tree.

Walnut trees are one of many tree species that are hosts to FHB.

Rijal said that if a grower found signs of an infestation last year, it is likely to re-occur this year. Rijal said FHB adults are attracted to stressed trees, and the drought conditions and extreme heat during the summer opened up opportunities for infestations.

Wounds on tree trunks, sunburned areas and other openings in the tree bark are likely openings for FHB egg-laying.

To confirm presence of FHB in an orchard, growers can peel back bark on a suspected branch and look for feeding tunnels packed with frass or larvae. Larval finds may be easier to find in the summer when feeding occurs just below the bark. The D-shaped exit holes can be found on infested tree limbs. Amber sap may be present.

Rijal said while pesticide controls for other walnut pests may have some effect on the adult FHB, there are currently no control methods in young trees. Growers who find extensive damage often opt to remove trees and replant. Protecting young trees from sunburn with paint can also prevent entry and egg laying.

No traps or lures have been found to be effective in monitoring FHB pressure. Rijal said trials to determine detection and control are planned for 2022.

Pistachio Stressors Interact

Pistachio trees have long been known for their ability to withstand tough environmental conditions.

How they adapt to environmental stress and what that means for commercial yields was discussed by UCCE Orchard Systems Specialist Giulia Marino in a 2021 Pistachio Day presentation.

When there is a change in the environmental conditions in an orchard, Marino noted, there is a physiological adaptation. The changes impacting a tree’s health can include a reduction in the chill hours during dormancy, elevated soil or water salinity, extreme heat or waterlogging. A tree’s response may impact its productivity.

“Plants have strategies to manage stress,” Marino said.

“There is never just one environmental stress, they interact and affect pistachio physiology.”

Pistachio trees have dual behavior in regards to water use. They are a drought-tolerant species with elevated water consumption. As water stress intensifies, leaf water use is reduced.

Marino compared pistachio orchards in Sicily where trees received four inches of water with San Joaquin Valley orchard systems where 40 inches of applied water is common. Yields in the San Joaquin Valley are much higher, Marino noted, but the water productivity for the crop in Sicily is much higher.

Efficient management of water uses the least amount to achieve the highest amount of production.

More research is needed, Marino said, to develop continuous, precise plant-based monitoring for water use. Adaptation of irrigation scheduling for alternate bearing and cultivar-specific water use is also needed.

Pistachio tree adaptation to saline conditions is more complex. Saline conditions have an osmotic effect on water uptake and an ion-specific effect on leaves. Energy expended to pull in water reduces the amount available for growth. Soil can also become degraded due to high salt levels.

Management includes using tolerant rootstocks and cultivars, winter leaching and soil amendments.

Growers also need information on growth prediction and planting strategies, NPK and pest management in saline conditions.

Impacts of waterlogging on an orchard are similar to drought, but less reversible. They include decay of root systems, leaching of nutrients and interruption of carbohydrate transport.

Temperature effects depend on the time of year. Ideal conditions are heat in the summer, early fall and spring and cold during winter dormancy. Cold temperatures during the spring can impact new growth. Warm temperatures during winter dormancy can cause erratic bloom and uneven maturity of nuts.

Almond Varieties Show Promise in Ongoing Regional Testing

Ongoing regional testing in Butte, Stanislaus and Madera counties continue to produce promising results for multiple experimental almond varieties.

UCD 18-20, an experimental pollinizer from UC Davis, and Booth from Burchell Nursery seem to be performing closest to Nonpareil compared to other varieties on the test plots (Table 1.) UCCE Pomology Farm Advisor Roger Duncan, who has been monitoring the test plots since 2014 along with UCCE’s Phoebe Gordon and Luke Milliron and UC Davis’ Bruce Lampinen, provided insight into the varieties’ success.

“Yield is probably one of the major things,” Duncan said in reference to what has stood out.

Cumulative 3rd-leaf to 7th-leaf yield data averaged from the three Central Valley test plots show UCD 18-20 and Booth at 10,940 pounds and 10,197 pounds, respectively, compared to the standard Nonpareil at 11,638 pounds.

USDA self-fertiles Yorizane and Y117-91-03 have also stood out in terms of yield, according to Duncan in UC ANR’s The Scoop newsletter, boasting a cumulative average of 10,140 pounds and 9,742 pounds, respectively. Of course, yield isn’t the only quality being assessed as ‘promising’ in these plots.

“When they’re promising, they appear to be compatible with Nonpareil (good bloom overlap), yielding well, and you don’t see any major drawbacks,” Duncan said. Hull split, harvest time, kernel quality and insect/disease susceptibility are also being assessed.

Bloom time, Duncan said, isn’t necessarily important for self-fertiles since they would theoretically be planted in a solid block in a commercial setting, but harvest time is. “We now have a lot of orchards that harvest at about the same time,” he said. “Nonpareil and Independence harvest at pretty much the same time. Shasta, which is a real up-and-coming self-fertile variety, also harvests at the same time. So, we would really like to see varieties that don’t harvest in that Nonpareil window.”

Varieties that help spread out harvest time are being increasingly sought after to relieve pressure on the processor side. Duncan said that early harvesting varieties are not common in almonds, but noted that Y117-91-03 is harvesting about one week before Nonpareil. Others, he said, are harvesting two to four weeks after Nonpareil, a good sign for increasing varietal options.

Duncan said in The Scoop that some varieties, including UCD 18-20, have a high percentage of doubles as well as other issues that might limit their adoption. For this reason, plantings of new varieties in commercial orchards are discouraged by UC until longer-term studies are conducted.

More information on experimental variety performance up to this point can be obtained by contacting Roger Duncan at raduncan@ucdavis.edu or (209) 525-6800.

 

Average Cumulative Yield for First Five Harvests, Canopy Size as Measured by Photosynthetically Active Radiation (PAR) and Yield per PAR.
UC Regional Almond Variety Trials Through 2020. Cumulative Yield 3rd – 7th leaf Average PAR Cumulative Yield / PAR
Self-fertile? Average of 3 Trials Butte County Stanislaus County Madera County
Nonpareil 11638 12949 8520 13446 69 169
UCD 18-20 10940 11412 9290 12118 64 171
Booth 10197 11312 8103 11176 72 142
Y117-91-03 Yes 10140 10103 9412 12142 67 151
Yorizane Yes 9742 9061 7965 13021 56 174
Capitola 9701 9727 8069 11307 74 131
Aldrich 9668 10989 8162 9855 63 154
Y117-86-03 Yes 9392 8256 7778 10764 58 162
Bennett-Hickman 9331 8660 8950 10324 63 148
Durango 9316 9944 7969 9699 64 146
Kester 9304 8660 7993 11260 67 139
Winters 9195 9923 7887 9777 61 151
Jenette 9161 10222 6185 11078 57 161
UCD 8-201 Yes 8910 8979 7167 10148 56 159
UCD 8-160 Yes 8821 8694 8353 9416 49 180
Sterling 8570 7888 7490 10061 69 124
Eddie 8422 7908 7255 10102 67 126
Folsom 8245 8693 6684 9368 71 116
UCD 1-16 8106 8171 6496 9650 60 135
Sweetheart 8005 7429 6806 10372 72 111
UCD 7-159 Yes 7966 7960 8129 7756 59 135
Supareil 7723 6964 6644 9292 76 102
UCD 1-232 Yes 7396 8181 6881 7034 58 128
UCD 8-27 Yes 7049 7438 5151 8349 64 110
Y121-42-99 Yes 6208 6208
UCD 3-40 5731 6940 5867 3940 68 84
UCD 1-271 Yes 5473 4887 6537 4836 61 90

Ag Burning Incentive Program Accelerates Phase-Out, Provides Alternatives for SJV Growers

Growers that might otherwise still be burning until the ag burn phase-out is complete have incentives available to accelerate adoption of alternatives to open burning.

The Alternatives to Agricultural Open Burning Incentive Program provides growers “incentives to chip or shred agricultural material from orchard/vineyard removals as an alternative to the open burning of the agricultural materials,” according to the program’s webpage.

Chipping with soil incorporation (discing/ripping/whole orchard recycling) and chipping without soil incorporation (land application of mulch or other on-site practices) are two alternatives that provide incentive values ranging from $300/acre to $1,300/acre depending on the type of operation (orchard, cane-pruned vineyard, cordon-pruned vineyard.)

A third alternative became available through the program as of September 1. “The additional option of off-site beneficial re-use has now been introduced… which does allow additional options,” said Crystal Yunker, supervising air quality specialist with the San Joaquin Valley Air Pollution Control District.

This alternative, which, according to Yunker, is currently being approved for incentive payments on a case-by-case basis, may involve practices such as mulching, composting or land application near roadways for dust suppression. Incentive values range from $600/acre to $1,300/acre depending on the type of operation. According to the program webpage, there is an additional incentive of $100/acre provided for each alternative to agricultural operations with less than 100 total acres within the San Joaquin Valley.

“The District has continually worked with agricultural stakeholders to identify alternatives for the disposal of agricultural waste and to make those alternatives more accessible to Valley growers,” said San Joaquin Valley Air Pollution Control District’s Heather Heinks.

Originally approved in 2018, the Alternatives to Agricultural Open Burning Incentive Program “recognized that substantial funding was needed to offset the costs of implementing new alternatives necessary to achieve the goal of a near-complete phase-out of agricultural burning by 2025,” Heinks said. “Thanks in part to lobbying efforts by the District, CARB and Valley agricultural leaders, the District was successful in receiving $178.2 million in grant funding for alternatives to agricultural burning to be spent over the next three years.”

Chipping contractors and agricultural operations are also eligible for funding to expand their existing fleets and chipping equipment, she added, but the program is currently oversubscribed and is no longer accepting new applications.

UC’s Statewide Pistachio Day Being Held Jan. 19-20

UC ANR will host its annual Pistachio Day virtually on Jan. 19-20, 2022. The event will deliver the latest research-based production practices to prospective or current growers, production managers and PCAs to better achieve their pistachio growing goals.

The first day will offer an industry overview as well as sessions on various important topics within the area of horticulture science, spanning from drought and water management to nutrition and biostimulant application. Additionally, some of the latest prediction tools for pistachio yield and nut growth will be introduced, and the day will end with some Golden Hills management tips and an update on breeding trials.

The second day will focus on food safety and integrated pest management. Presentations will give new insights into the management of Phytophthora root and crown rot, Alternaria late blight and Gill’s mealybug. Methods to alleviate high aflatoxin contamination in pistachio will be also presented as well as an integrated pest management program for navel orangeworm. The day will conclude with an overview on the development of sterile insect technique for navel orangeworm.

To register for the 2022 Statewide Pistachio Day, click here. To sign up for Pistachio Day announcements and notifications, click here.

Stay Ahead of Orchard Weeds During Winter

UCCE Weed Specialist Brad Hanson recommends growers start getting vigilant now and conducting weed surveys as they walk their orchards after harvest. “I would do a survey ahead of any kind of [post-emergent] application window for sure,” he said. “If I’m out there after harvest, I want to get a sense of what weeds are coming up now because that’s going to dictate what’s in my tank mix.”

Preemergent applications, Hanson said, should be based on records of what happened last winter or spring. “It’s two parts: You want to know what’s out there now that you need to control, but also what was there that will probably be there again next year.”

Hanson noted that complicated weed survey plans for orchards are typically overkill, adding that surveying mostly requires simply going up and down representative blocks to get a sense of weed presence.

In walnut orchards, annual weeds to look out for in January and February include annual bluegrass, California burclover, common chickweed, little mallow (aka cheeseweed) and mustards among others. Some annuals, however, can provide similar functions to cover crops, according to UC IPM guidelines.

Hanson said that many growers in Northern California, particularly those with more clay in their soils, will leave these weeds, or “resident vegetation,” in orchard rows to reduce erosion, soil compaction and water and sediment runoff. “Many of the same cover crop functions are managed by the vegetation that’s there naturally,” he said. “It’s really a matter of if you’re okay with that particular vegetation or if you want to change it to something else.

“If it’s filaree and ryegrass, that’s probably not so bad. If it’s malva and hairy fleabane, or some kind of perennial weed, that might be something you want to have control of,” he added.

Perennial weeds should not be left in orchards. UC IPM guidelines recommend checking groundcover in row middles for perennial seedlings and regrowth of perennials a few weeks after cultivation. Perennials to look out for include bermudagrass, curly dock, dandelion, dallisgrass and field bindweed among others.

The grower’s final decision for keeping resident vegetation in their orchards will be dependent on the particular species, orchard location and goals for said orchard, according to Hanson. Different functions of vegetation require different management inputs.

“If [the grower] wants 100% weed control, that’s going to require a certain level of input,” he said. “If they want to get a certain functionality with vegetation, that might be a different kind of input.”

Navel Orangeworm Rejects on the Rise

While the amount of Nonpareil almond rejects due to navel orangeworm (NOW) damage varies from season to season, Blue Diamond Growers has noted a concerning uptick over the past 10-plus years. With the upward trend comes opportunity losses from reduced or no grower premiums.

UCCE farm advisors and Blue Diamond staff point to not one, but a combination of factors that likely are responsible for the increasing rejects.

“It’s hard to say exactly what’s going on,” said Jhalendra Rijal, UCCE IPM advisor for Stanislaus, San Joaquin and Merced counties. “It could be multiple factors at play.”

Among potential contributors are drought conditions, larger nut crop acreage that provides increased continuous hosts, the availability and cost of polling crews for winter sanitation and pesticide resistance.

As a result, Extension and industry representatives recommend growers double down on their IPM practices, which start with foundational winter sanitation. Proper timing of the other IPM practices is also crucial, whether it is hanging monitoring traps in the spring, putting out mating disruption dispensers, applying hull split sprays or harvesting.

Rejects Up in 2021
So far this season, Nonpareil overall reject levels are running about 1.75%, second only to the “train wreck” of 2017 and 2018, said Mel Machado, Blue Diamond vice president of member relations.

In the past, about 80% of the rejects could be attributed to NOW damage. But that’s not the case anymore. While NOW still comprises the bulk of the rejects at 53%, he said other problems, such as brown hole, are on the rise.

“NOW is still the primary problem out there, but primary is a relative term,” Machado said. Rather than looking at average reject levels, he said he prefers to look at how much of the crop goes into the co-op’s quality programs.

Based on the amount of the Blue Diamond crop run as of late October, about one-third failed to make grade and was considered standard. Broken down, the northern production area was running 38%, the central 25.7% and the south 44%.

“That’s stunning, 44%,” Machado said. “Even in 2017, it was 37%.”

When Machado compared the crop going for meats to that destined for in-shell, the differences were glaring.

Only 12% of in-shell failed to make grade. He attributed it to varieties that have tighter seals, making them less susceptible to NOW. Growers also are more aware of reject levels for the in-shell market and manage accordingly.

The Foundation: Winter Sanitation
At the heart of NOW management is winter sanitation, which not only removes mummies in which larvae overwinter but also eliminates egg laying sites for the first NOW flight in the spring.

Make timely hull split sprays, keeping in mind that nuts at the top of trees typically split before those at eye level (photo by V. Boyd.)

Franz Niederholzer, UCCE farm advisor for Colusa, Sutter and Yuba counties, recommended surveying orchards for mummies on or before January 15. Count the mummies on 20 representative trees and average the results. This should be done for each variety, regardless of shell thickness or seal, within the orchard.

If there are more than two mummies per tree, plan to mechanically shake or have a crew hand-poll the trees to remove them before bud swell. In the central to southern parts of the Central Valley, David Haviland, UCCE farm advisor in Kern County, recommends striving for fewer than one per tree.

But the increased cost and reduced availability of polling crews has made winter sanitation more challenging, he said. Afterward, the orchard floor should be disked or flail mowed by March 1 to destroy mummies on the ground.

Mummies not only provide an overwintering site for larvae, they also offer egg-laying sites for the first NOW moth flight in the spring (photo by V. Boyd.)

The optimum time for winter sanitation is after a heavy dew, fog or rain when the mummy nuts have absorbed some moisture. This makes them heavier and easier to shake and remove. The moisture also helps rot mummies in the trees as well as aids larval mortality on the orchard floor.

Unfortunately, Haviland said, the southern San Joaquin Valley never received heavy rains last winter.

“The ground remained bone dry all winter long,” he said. “Even if a mummy is below ground and it doesn’t get wet, a larva can emerge if it’s in the top few inches. Shallow-buried mummies never got wet.”

Rijal said sometimes growers and PCAs think that instead of shaking they can apply an insecticide to the mummies due to understandable reason, such as dry winters and labor shortages.

Regardless, he said, “We cannot beat the navel orangeworm if we only rely on insecticides, and we need to find ways to do the winter sanitation effectively. In fact, for winter sanitation, any time after the harvest through early February works. For example, we had some rain last week, and mummy sanitation can be done now if you can.”

Mating Disruption
In response to NOW control challenges, almond, pistachio and walnut growers representing more than 400,000 acres combined have successfully incorporated in-season mating disruption into their IPM programs, Haviland said.

Among adoptees is Niederholzer, who also is manager of the Nickels Soil Lab.

“Over the past two years at Nickels, we’ve had some of the best control measures of the last 10 years,” he said.

Many growers like to wait for dew, dense fog or some rain before they shake mummies in the winter (photo by V. Boyd.)

Hung in orchards in the spring, pheromone dispensers emit chemicals throughout the season that imitate those produced by female NOW. This confuses male moths, preventing them from finding females with which to mate. The system works best on large, contiguous blocks, but Haviland said even smaller-scale growers have seen benefits.

“We know it works on 40 acres in almonds,” he said. “We know it works better on 100 acres, and anything over 100 is just bonus.”

While not a silver bullet, mating disruption can help eliminate at least one in-season NOW treatment, according to UCCE.

Hull Split Sprays
Although insecticides are part of NOW IPM, they alone may only be 50% effective, and in many cases, less, Rijal said.

“Every time I do a trial with insecticides, I never reduce damage to zero even though I dip the nuts in a solution,” he said. In other words, insecticides at hull split are critical, but they cannot solve all of the problems and need to be combined with other control measures.

At least a few growers in the northern Sacramento Valley have put tracks on their shakers so they can remove mummies even in wet orchards (photo by F. Niederholzer)

Insecticide choice also has grown more challenging as NOW has become less sensitive to the pyrethroid class of chemistries, Haviland said.

“Generally, pyrethroids are not working as well as they used to; there’s definitely pyrethroid resistance,” he said.

Application timing is critical as the hulls split and the nuts become susceptible to NOW egg laying.

Larvae can overwinter in mummies left on almond trees after harvest (photo by V. Boyd.)

Machado said growers should time hull split sprays based on the crop stage, not the moth flight. Where they may get into trouble is not noticing the nuts in the tree tops that typically split before those at eye level.

“They need to be watching the tops of the trees, whether that’s with a pruning tower or long hook,” Machado said. “If you look where the nuts are in the canopy, they’re in the tops of the trees.”

“Timely” Harvest
While some talk about an early harvest to possibly avoid the third NOW flight, Machado prefers the term “timely harvest.”

“What’s the goal?” he asked. Is the crop going for meats or for in-shell, since the two end uses prompt different harvest timing.

Even then, it’s a balancing act. Ideally for the meat market, Extension recommends shaking when 100% of the nuts are one-half to two-thirds of the way split and the hull is still green, known as stage “d”. With some varieties, growers have found that harvesting at stage “c”, when the hull split is 0.25 to 0.5 inch, allows for a cleaner shake.

The lack of availability and increasing cost of polling crews have prompted many growers to rely solely on mechanical mummy removal (photo by V. Boyd.)

Harvest significantly earlier, and resulting higher moisture levels will mean the nuts have to sit on the ground longer to dry. This makes them potentially susceptible to additional ant damage, Machado said. Going too early also may mean the brown kernel skin hasn’t set adequately, and you get more “peelers”.

On the other hand, if you let the nuts dry for a prolonged period on the tree, you expose them to an increased egg laying potential from the third NOW flight. The hulls also cup and become tough, making them more difficult to remove.

For the in-shell market, Machado said growers should wait until the hulls butterfly before they harvest. Leaving the nuts on the tree longer also exposes them potentially to more NOW egg laying. If the orchard was managed with high fertility, toxins from hull rot also could build up with later harvest, creating more stick-tights.

To determine how well their NOW program worked during the season, Rijal said growers shouldn’t just rely on handlers’ grade sheets. In addition, they should collect field samples at harvest because up to half of damaged nuts are left in the orchard and aren’t reflected in the reports.

“Take multiple samples of 500 to 1,000 nuts representing the orchard and crack the nuts out,” he said. “It helps to know what’s going on and also look at the history of the orchard.”