Are California almond growers really going to reach their record 3 billion pound crop this year? How have the wildfires impacted the harvest season? What kind of pest pressure levels are growers experiencing this year? What should almond growers expect at the virtual Almond Board Conference this year? Watch this brief interview with Richard Waycott from the Almond Board of California to find out and read more about it in Pacific Nut Producer Magazine.
Please thank this video’s sponsor Suterra for their industry support.
Navel orangeworm (NOW) is the key pest of almonds, causing more income loss due to reject nuts than any other pest. Pesticide sprays, alone, cannot control this pest. A combination of several specific practices has been proven to reduce NOW damage and limit loss of grower income. These practices are winter sanitation, timely harvest and pesticide sprays (where needed). Mating disruption is an additional option that is seeing increasing adoption. The first of these practices on the orchard calendar is sanitation.
Navel orangeworm find food and shelter in unharvested (“mummy”) nuts through the winter and spring, making those mummies a bridge of trouble from one year to the next in your orchard. Multiple research studies show that NOW damage increases with increasing mummy counts the previous winter. Destroying mummy nuts is the first step towards a cleaner crop and improved grower returns through quality incentives from processors. The goal of orchard sanitation is to turn that “NOW bridge” from a four-lane highway (no sanitation at all) into a narrow footbridge.
Orchard sanitation is practiced by removing mummy nuts from the trees by February 1 and destroying (flail mow or disc) all nuts on the orchard floor no later than March 1st. In light of the expected reduced nut price for the 2020 crop, some growers may consider eliminating this key step in NOW management to “save money”. This is a risky move. The Sacramento Valley 2021 crop has a good chance to be lighter than the record 2020 crop resulting in 1) fewer nuts/tree and so higher % damage even if NOW populations stay the same and 2) larger nuts, on average, with the potential for poor shell seal and greater risk of NOW damage. Don’t play Navel Orangeworm Russian Roulette with your next crop. Sanitize.
The following steps are needed for effective orchard sanitation:
Before January 15, scout an orchard and count mummy nuts in 20 trees per acre. Include all varieties in this count.
If average number of mummy nuts/tree exceeds 2, sanitation is recommended. The <2 mummies per tree target was developed in the early 1980’s, when industry average NOW damage was around 3.5%, much higher than today’s range of 1.3%. In the high pressure area of the southern San Joaquin Valley, the recommendation is to limit mummies to 1 per 5 trees (0.2 nuts/tree) and 8 or fewer mummies on the ground per Nonpareil tree, based on research from in 2003-2006 in Kern County. However, in 2019, northern California had higher % rejects level than the “high pressure” south San Joaquin Valley. Simply put, the fewer mummy nuts in an orchard, the lower NOW pressure at the start of the season.
To sanitize, shake trees to remove nuts by January 31. Shaking can remove flower buds as they begin to swell and gain weight in late January/early February. Unless it is an early bloom season and buds begin to swell ahead of normal timing, shaking can be done into early February without reducing yield. Some buds are removed by shaking in early February, but since only 25% flower set = good commercial crop, some bud loss does not mean less crop at harvest. Some growers hand poll after shaking if too many nuts remain.
Sweep downed nuts into windrows and mow or disc by March 1. Mow slowly (2 MPH) and check for intact nuts after mowing. If some nuts remain intact, mow again. NOW can survive if the nut is intact.
Final thought. NOW overwinter in almond, walnut and pistachio mummies. NOW are also strong flyers, traveling at least a quarter of a mile to lay eggs. If you sanitize, but your neighbor(s) don’t, your orchard is at risk from NOW damage due to mated female moths, ready to lay eggs, flying over from the neighbors. Talk with your neighbors about sanitizing all orchards in the area and removing seedling “wild” almonds along fence lines as these can harbor NOW, too. — By Franz Niederholzer, UCCE Farm Advisor, Colusa & Sutter/Yuba Counties
With almond and walnut harvest underway, it is a good time to review harvest nut sampling strategy and protocols for the best estimation of field loss by common pests. It is a general understanding that the grade sheet from your processers only represents about half of what is going on in the field. Also, the whole sum percent damage from the grade sheet does not identify which pest is causing the most economic loss. Insect population in orchards builds over time; therefore, knowing the history of damage helps to address potential risks and strategies to next year’s pest management program.
1. Harvest Sampling in Almonds
Taking a minimum of 500-1000 sample nuts from an average-sized orchard, anytime between shaking and sweeping, is recommended. Infestation can vary among different sides of the tree, and between edges and interiors of the orchard. This is especially true for navel orangeworm damage. Use paper bags to collect samples from multiple spots (>10 sampling spots, if possible) within the orchard. Store the sample bags in a cold room or freezer until you have time to do crack out. Look for damage signs associated with insect species described in the following paragraphs. Major insect pests for the damage evaluation are navel orangeworm (NOW), peach twig borer (PTB), oriental fruit moth (OFM), ants, leaffooted bugs (LFB), and brown marmorated stink bug (BMSB). BMSB is an invasive stink bug species, which is established and causing damage in almond orchards in the northern San Joaquin Valley.
1.1. Worm Damage (NOW, PTB, OFM). NOW feed in the kernel (nutmeat) and create deep feeding tunnels. Feeding by NOW results in a significant amount of white frass, and webbings on the kernel (Fig. 1a). Since NOW and PTB often infest the same nut, NOW feeding damage often masks the PTB damage. Feeding damage signs by PTB and OFM on the nutmeat are similar (i.e., the presence of the shallow tunnels and surface grooves on the kernels, and no webbings) (Fig 1b & 1c), except OFM leaves a small amount of reddish frass on the hull, which is absent in PTB damaged nuts.
Fig. 1. Almond kernels (nutmeat) damaged by: a) navel orangeworm, b) peach twig borer, c) Oriental fruit moth
1.2. Ant Damage. The percentage of almond damage by ants at harvest depends on the duration the nuts are on the ground after shaking. The longer almonds are left on the ground gives more time for ants to feed on them, results in more damage. Also, more damage is likely in orchards with drip or sprinkler irrigation compared to orchards with flood irrigation. Cover or vegetation in the orchards also favors ant activity. Nuts with tight shells or with narrower (<0.03-inch wide) hull split have less ant damage. Ants can completely hollow out the nutmeats and leave only thin skin (i.e., pellicle). Other signs of ant feeding damage include scraped or peeled pellicle and presence of “sawdust”, with the absence of webbings and frass (Fig 2a).
1.3. Leaffooted Bug and Brown Marmorated Stink Bug Damage. Most nuts infested by the leaffooted bug or BMSB, early in the season (mid- March to mid-May), abort and drop. A small percentage of those infested nuts do not drop but end up becoming shriveled and gummy kernels at harvest (Fig 2b). Both LFB and BMSB feeding after the shell hardening can result in sunken dark spots on kernels (Fig. 2c), although the degree of damage tends to be higher with BMSB feeding than LFB. Late-season feeding (July-August) by BMSB, can cause dark stained kernels (Fig 2d). Varieties with soft shells such as Fritz, Sonora, Aldrich, Livingston, Monterey, and Peerless are more susceptible to bug damage and for a longer period during the season.
Fig. 2. Almond kernels damaged by: a) ants, b-d) leaffooted bug and brown marmorated stink bug
2. Harvest Sampling in Walnuts
It is recommended to take a minimum of 1000 nuts at the harvest and evaluate for the damage caused by navel orangeworm , codling moth, ants, husk fly, and sunburn. It is important to have representative samples (>10 samples with a minimum of 100 nuts/sample) from the orchard for better estimation of the infestation. The damage signs associated with these specific insect pests and sunburn are described as follows:
2.1. Worm Damage (NOW, CM). Navel Orangeworm damage can be identified by the presence of a large amount of frass and webbings (Fig 3a). NOW larvae are present in groups and can bore deeply into the kernel. Heavy infestation may give a nutshell an oily appearance. In contrast to NOW, a single codling moth larva infest the nut, and has a lot cleaner damaged area inside the nut. Frass is evident, but only at the entry point on the husk; very little webbing present (Fig. 3b). If larva is present, look for crescent-shaped marking just behind the head to confirm navel orangeworm.
Fig. 3. Walnut damaged by: a) navel orangeworm, b) codling moth
2.2. Ant Damage. Similar to almonds, nut damage by ants increase as the duration of the harvested nuts on the ground increase. Ants enter the nuts from the soft tissues (i.e., stem end) and/ or through a codling moth injury. Ant damage on nuts is identified by the presence of deep chewing channels with clean kernels (i.e., no frass, no webbings, no deep boring) (Fig 4a).
Fig. 4. Walnut damaged by: a) ants; b) walnut husk fly; c) sunburnFig. 5. (Left) Brown Apical Necrosis is shown on the left, not to be confused with Walnut Blight, shown on the right, and caused by the bacterial pathogen, Xanthomonas arboricola pv. juglandis (Figure provided by Themis Michailides).
2.3. Husk Fly Damage. Walnut husk fly larvae (technical term: maggots) feed in groups by boring into the husk. Early season damage results in shriveling and darkening of the kernels, with the increased potential for mold growth. Late- season infestation causes little kernel damage (Fig. 4b), although it may stain the shell and make the husk removal process difficult.
Fig. 6. (Right) Moldy, off color nuts which lead to economic loss due to downgrading (Figure provided by Themis Michailides).
2.4. Sunburn Damage. Sunburn damage on nuts can be confused with husk fly damage. In the case of sunburn, nutmeat is shriveled and darkened on one side of the nut — no evidence of frass, webbings, or larval presence (Fig. 4c). Husks from sunburn damaged nuts can be removed from the shell during processing, which is not the case for the nuts damaged by husk fly.
— Article by Jhalendra Rijal, PhD, UCCE IPM Advisor, Stanislaus, Merced & San Joaquin Counties
Most tree nut growers have heard about the sterile insect technique research underway to combat Navel Orangeworm, the number one pest threat to almond and pistachio growers. But what is the progress on this program and how soon can we expect to see these sterile insects released on a large scale to support California growers? Watch this brief interview with Houston Wilson from the Kearney Ag Research & Extension Center, UC Cooperative Extension, to learn more.
Please thank this video’s sponsor Suterra by taking this brief Survey.
Representative Josh Harder (CA-10) today led a bipartisan letter to United States Department of Agriculture (USDA) Secretary Sonny Perdue, asking him to use his authority to utilize all purchasing authorities to buoy the struggling walnut industry. The walnut industry – based exclusively in California – has seen prices plummet in the last two years to near or below the costs of production. Even prior to the outbreak of the Coronavirus, walnut farmers were harmed by retaliatory tariffs levied by top export partners including China, India, and Turkey. Rep. Harder is joined on the letter by fellow California Reps. Devin Nunes, Jim Costa, TJ Cox, Salud Carbajal, John Garamendi, Jerry McNerney, Jimmy Panetta, and Doug LaMalfa.
“Walnut growers are being pinched on all sides – they’re up against tariffs from other countries, falling demand, and general chaos in food markets,” said Rep. Harder. “We have USDA programs designed for use in emergencies just like this – the Secretary should use them right away to help our walnut farmers.”
“We are incredibly grateful to Congressman Harder and colleagues for recognizing the need to support California’s walnut growers,” said Michelle McNeil Connelly, Executive Director of The California Walnut Board. “We continue to face challenging times and greatly need Section 32 to provide relief. As an essential industry we have continued to do our part and believe the relief funds provided to USDA will provide an excellent source on nutrition for millions of hungry Americans while, in tandem, ensuring the viability of our producers.”
Michelle McNeil Connelly, Executive Director of The California Walnut Board
The letter asks Secretary Perdue to use two legal authorities to increase walnut purchases. The first, Section 32 of the Agricultural Adjustments Act allows USDA to support the ag industry by purchasing their products at market rates and then distributing the products to people in need. The letter also asks the Secretary to use his authority under the Food Purchase and Distribution Program, which was created last year to help farmers harmed by trade wars with other countries.
The text of the letter is below and an original copy is available here.
Dear Secretary Perdue:
Thank you for your leadership overseeing the U.S. Department of Agriculture (USDA). We write today in support of USDA purchases of California walnuts and encourage utilizing all purchasing authorities, including Section 32 and the Food Purchase and Distribution Program, to provide much-needed support to California’s walnut industry.
Representative Josh Harder (CA-10)
The COVID-19 pandemic has come on top of an already difficult time for our 4,500 California walnut producers who have, and continue, to suffer from the effects of retaliatory tariffs in India, Turkey and China. From tariff actions alone, what was a $1.5 billion industry just two years ago, has declined by more than 41 percent to $878.8 million. Producer prices have been near or below the costs of production for the last two years (0.65/cents per pound) and the outlook is bleak. The continued impacts of COVID-19 have resulted in excess inventories, with a record carry-out of nearly 90,000 tons from the current crop compounded by an anticipated record crop in excess of 700,000 tons which will begin harvest in September. The California Walnut Board estimates initial farm gate losses from COVID-19 at nearly $300 million, and as with this pandemic, are evolving and eroding quickly.
Global walnut demand has slowed resulting from port disruptions, distribution challenges, the sharp decline of the food manufacturing and food service sectors, and consumer economic uncertainty. With the trajectory of COVID-19 lasting well into 2021, walnut producers are in need of assistance from any and all programs available to protect the 85,000 full-time jobs attributable to the walnuts industry. Our California’s walnut farmers represent ninety-nine percent of U.S. production of walnuts, were the 5th leading export from the state prior to these challenges. Despite falling to the 13th leading export from the state, the California walnut industry contributes over $6 billion to the state’s economy.
Demand for nutrition programs has grown immensely, with Feeding America reporting that 98 percent of food banks reported an increase in need for food assistance. In California alone, food bank demand has grown by 73 percent, while farmers and ranchers have seen market declines of over 50 percent. Walnuts provide a shelf stable source of protein and essential omega-3 fatty acids, providing nutrition to feed America’s hungry through meal inclusion and snacks, while also aiding our farmers.
We appreciate your previous support for the industry, through purchases and the Market Facilitation Program, and hope your support will continue through this pandemic. We thank you for your continued support during this unpredictable time and urge you to give all due consideration to California’s walnut industry’s purchase request.
Italian ryegrass is a major weed in orchards, vineyards, field crops, and fallow fields of California (Figure 1). Several different herbicides are used to control ryegrass and had been effective in reducing infestations until resistance evolved in many populations following repeated use of the herbicides. To date, resistance to glyphosate, paraquat, and some ACCase and ALS inhibitors has been confirmed in ryegrass infestations across the agricultural landscape of California. To make matters worse, resistance to multiple postemergence herbicides with different modes of action has been confirmed within the same orchard, vineyard, or field in some areas. Consequently, management of Italian ryegrass in California annual and perennial cropping systems has become a major challenge.
Figure 1. High infestation of Italian ryegrass in a peach orchard (photo credit: Maor Matzrafi).
Glufosinate is an alternative non-selective postemergence herbicide that can still be used to control herbicide-susceptible and most herbicide-resistant Italian ryegrass in California as only two populations with resistance to glufosinate have been documented to date. However, the higher cost of glufosinate relative to other herbicides may drive farmers to apply glufosinate at reduced rates as has occurred in other cropping systems, such as the Australian wheat belt, with other herbicides. The lower rates and other drivers such as herbicide applications at non-optimal weed size, inappropriate weather conditions, and insufficient spray coverage may result in sublethal rate selection of ryegrass by glufosinate.
To evaluate the potential for low glufosinate rates to select for reduced susceptibility to the herbicide, and to determine if selected populations are cross-resistant to herbicides with other modes of action as has been observed in a few studies, we conducted a greenhouse study using a herbicide-susceptible parent population originally collected from a vineyard in Sonoma County. Plants were grown in the greenhouse to the 3-4 leaf stage and treated with low glufosinate rates for three generations. For the first round of selection, plants were treated with glufosinate at 1/8X, 1/4X, and 1/2X of the labelled field rate (984 g ai ha-1). Surviving plants were grown to reproductive maturity and allowed to cross-pollinate. Seeds were harvested from all plants, pooled, germinated, and plants grown in the greenhouse for the next round of selection at slightly higher rates (1/2X, 3/4X, and 1X). For the third round of selection, plants were treated at 3/4X, 1X, and 1.25X of the labelled field rate.
Results showed that susceptibility to glufosinate was reduced in offspring in comparison with the susceptible parent population following only three generations of selection (Figure 2). Comparing the susceptible parent population with the offspring from the second and third selection cycle, the percentage of surviving plants increased to values of LD50 (1.31 and 1.16, respectively) and LD90 (1.36 and 1.26, respectively).
Figure 2. Dose-response of the Italian ryegrass susceptible parent population (P0) and three successive generations (P1, P2, P3) of offspring following selection with low glufosinate rates in the greenhouse. Lines are the predicted values for percent survival. Red arrow indicates the labelled field rate (984 g ai h-1). Adapted from Matzrafi et al., 2020 (https://www.biorxiv.org/content/10.1101/2020.07.04.182733v1).
When treated with alternative postemergence herbicides (glyphosate, paraquat, or sethoxydim), no plants of either the parental or successive offspring populations survived treatment with 0.75X or higher rates of these herbicides (see Matzrafi et al., 2020 (https://www.biorxiv.org/content/10.1101/2020.07.04.182733v1).
The magnitude of increases in resistance levels over three generations of recurrent low-rate glufosinate selection observed is relatively low compared with higher levels of resistance observed in response to low-rate selection with other herbicides (three-fold and greater). However, under field conditions, even low levels of resistance within weed populations may reduce control. This study shows that repeated selection with glufosinate at low rates can reduce the susceptibility of Italian ryegrass populations to glufosinate, and points to the importance of incorporating a diversity of approaches, both chemical and non-chemical, in the management of ryegrass in annual and perennial cropping systems of California. – By Marie Jasieniuk & Maor Matzrafi, UC Weed Science
The Oregon Department of Agriculture (ODA) has approved SLN No. OR-200011, a Special Local Need registration under FIFRA Section 24(c), to allow use of the Albaugh, LLC product Quinstar® 4L, EPA Reg. No. 42750-169, for control of field bindweed and other weeds in hazelnuts (non-bearing only) grown in Oregon. The label and completed EPA Form 8570-25 for this SLN are enclosed.
Oregon produces more than 99% of the total U.S. hazelnut crop. In a letter of support for this SLN registration, Michelle Armstrong of the Oregon Hazelnut Commission states that there are now more than 89,000 acres of hazelnuts planted in the state. The acreage in production has more than doubled in the last 10-15 years, as new varieties that are resistant to eastern filbert blight (EFB) have become commercially available. As the industry has been rapidly expanding during recent years and older EFB-infected trees are replaced, several thousands of acres of new orchards are being planted each year. It typically takes about four (4) years or more after an orchard is planted before it is bearing a harvestable crop.
According to the Hazelnut Commission and Dr. Marcelo Moretti, Oregon State University (OSU) Extension Weed Management professor, the management of perennial weeds such as field bindweed is one of the most challenging problems faced in orchard crops. If left uncontrolled, field bindweed can quickly overgrow young plants, such as newly planted hazelnut trees. Selective and systemic herbicides are the most effective tools for managing perennial weeds such as bindweed, but hazelnut growers have limited options available. Essentially, their options are limited to 2,4-D and glyphosate products.
Glyphosate use is restricted in hazelnut orchards during the season because of crop injury concerns; spot-spraying is widely practiced, but is time-consuming and not very effective and may only be used to treat weeds away from the trees to avoid crop injury. Efficacy of 2,4-D against bindweed is also limited, and concerns with volatilization and drift may also restrict its use to only short periods during the season. Meanwhile, contact herbicides registered for use on hazelnuts, such as glufosinate, carfentrazone, saflufenacil, and paraquat, provide only transient removal of the treated foliage, with negligible impact on survival of the weed plants.
Albaugh, LLC applied for this SLN registration for use of Quinstar® 4L on hazelnuts to address the growers’ special local need for an effective product for controlling field bindweed and other weeds growing on the orchard floor and in close proximity to the newly planted and young hazelnut trees during the growing season, without crop injury concerns.
Dr. Moretti has been evaluating quinclorac and other herbicides in long-term field trials conducted in several different young/non-bearing orchards and across multiple hazelnut varieties and trees ranging from one to four years old. The results of these studies thus far (two years in) strongly indicate that the young hazelnut trees are very tolerant of quinclorac. No crop injury or negative impacts to the trees has been observed from quinclorac applied at rates up to 1.5 lb. active ingredient per acre. By comparison, Dr. Moretti’s studies in other crops in this growing region demonstrate excellent control of field bindweed at rates of 0.375 lb. a.i. per acre (12.6 fl. oz. Quinstar® 4L per acre), which is the application rate provided by this SLN registration.
No residue tolerances have been established to support food-use applications of quinclorac on hazelnuts (Dr. Moretti currently is pursuing quinclorac/hazelnut [Crop Group 14-12, Tree Nut Group] residue studies with the IR-4 Project). Therefore, use under this SLN registration is limited to non-bearing hazelnuts only.
David L. Priebe State Registration Specialist Pesticides Program Oregon Department of Agriculture Phone: (503)986-4656
The U.S. House of Representatives Appropriations Committee recently released an appropriations bill that included $8 million for the facility in Phoenix, AZ that is currently being used to rear sterile navel orangeworm (NOW) for aerial release in California. The facility is part of an area-wide pilot program that the pistachio and almond industries have been interested in developing. For 2020, Congress appropriated $6 million to keep the facility open and start the pilot program. This year, APG led an effort to continue and increase that funding, which included a delegation trip back to Washington, D.C. right before COVID-19 forced much of the city to shut down. This additional $2 million will allow the pilot program to not only continue to conduct research on sterile moth releases, but also begin to expand the breadth of the research. With positive momentum in the House, APG will now turn to lobbying efforts in the U.S. Senate.
About the Facility The Phoenix Sterile Fly Facility was originally commissioned by the cotton industry to raise sterile pink bollworm for area-wide releases in an effort to suppress the pest. The program was even more successful than planned and the cotton industry was recently able to declare pink bollworm eradicated. Now that the facility has excess capacity, pistachio industry leaders have begun breeding sterile NOW for aerial release in California. — By American Pistachio Growers
Are California almond growers really going to reach their record 3 billion pound crop this year? How have the wildfires impacted the harvest season? What kind of pest pressure levels are growers experiencing this year? What should almond growers expect at the virtual Almond Board Conference this year? Watch this brief interview with Richard Waycott from the Almond Board of California to find out and read more about it in Pacific Nut Producer Magazine.
Final thought. 
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