Rats have taken an unusual interest in the specialty crop capital of the nation. Many attribute the cause to the pest multiplying unchecked in orchards and vineyards in the Central Valley that have been abandoned due to water restrictions and economic challenges. This becomes a real problem when the rats move into neighboring farms in active production, tearing up driplines, feeding on crops and damaging trees. Growers are in a state of emergency and have limited tools for managing this pest.Malcolm Media Editor-in-Chief Matthew Malcolm met with UCCE Wildlife Specialist Roger Baldwin at the California Association of Pest Control Adviser’s annual conference to gain answers on how to knock down populations effectively and keep the pest at bay.Watch this brief interview and learn more by attending Baldwin’s presentation on rat control at the Grape, Nut & Tree Fruit Expo at the Fresno Fairgrounds on Nov. 14 (register to attend at agexpo.biz).
Got voles on the farm and don’t know how to get rid of them? Oregon State University researchers are coming to the rescue. Watch this brief interview as Malcolm Media Editor-in-Chief Matthew Malcolm meets with Oregon State University representatives Dana Sanchez and Joshua Twining share advice on how to manage them, as well as new research developments on how to better understand their behavior and how they respond to modern mitigation techniques.
American Pistachio Growers (APG), in collaboration with Washington State University, University of California – Riverside, UC Cooperative Extension, the USDA Agricultural Research Service and regional nut industry partners, has been awarded a $1 million grant through the California Department of Food and Agriculture’s Biologically Integrated Farming Systems (BIFS) Program to develop a Regional Integrated Pest Management (IPM) network for Navel Orangeworm (NOW) — the most damaging pest in California’s tree nut industry.
The project, led by Dr. Houston Wilson (UC Riverside), Dr. David Crowder (WSU), Dr. Jhalendra Rijal (UC IPM), and Dr. Charles Burks (USDA ARS) will pilot a groundbreaking Decision Aid System (DAS) that integrates real-time trap data, weather models, and crop phenology into a single communication platform. The goal is to improve the timing and precision of pest control decisions while fostering regional cooperation among almond, pistachio, and walnut growers.
“This project moves us beyond the farm gate,” said Joe Coelho, APG’s Director of Sustainability and Member Outreach, who serves as Technical Agronomist and PCA on the project. “For the first time, growers across commodities will have access to shared regional data and communication tools that allow them to anticipate pest pressure before it hits their fields and ultimately make precise, timely treatment decisions. The outcome is fewer sprays, lower costs, and higher quality nuts.”
Through field-level data acquisition, the system’s meta-analytics will identify regional flight trends coupled with crop-specific phenological development and enhance forecasting of NOW flights — critical steps in breaking the pest’s lifecycle across neighboring farms. Ultimately, the program is expected to help reduce pesticide use, improve nut quality, and lower aflatoxin risk associated with pest damage.
APG will serve as the grower administration partner, coordinating grower participation and outreach. Carlee Branco, APG Grant Programs Administrator, will conduct on-farm grower coordination, engagement and data collection. “This is a major milestone for sustainable pest management,” said Coelho, “and it demonstrates APG’s leadership in advancing research that directly benefits growers.”
The Regional IPM for Navel Orangeworm Project represents a pivotal step toward the state’s Sustainable Pest Management (SPM) Roadmap by providing a scalable, data-driven framework that can be expanded statewide.
“This is exactly the kind of innovation California agriculture needs,” said Dr. Wilson. “Regional coordination is essential to long-term pest reduction, especially for highly mobile insects like the navel orangeworm, and this project will now put those ideas into practice at scale.”
The program launches in early 2026, with pilot regions in West Fresno County and Modesto, serving as the foundation for a future statewide expansion. Growers within these territories who are interested should contact Carlee Branco for more information at cbranco@americanpistachios.org.
American Pistachio Growers (APG) is a non-profit trade association representing more than 800 growers and processors across California, Arizona, and New Mexico. APG’s mission is to enhance grower profitability through global marketing, industry research, and sustainability initiatives that promote economically viable and environmentally responsible pistachio production.
Stop Tough Broadleaves from Cluttering Orchard Floors with Rinskor® active
Sponsored Content
California tree crop producers can now choose Hulk® CA herbicide, featuring a new active ingredient for the tree crop market, to strengthen their herbicide resistance management efforts. Producers also get reliable control of challenging broadleaf weeds to maintain cleaner orchard floors.
With systemic activity that translocates to key weed-growing points for thorough knockdown, Hulk CA herbicide prevents regrowth of treated weeds and can be integrated into most weed management programs. It is also tank-mix compatible with other herbicides and complements a preemergence or burndown program in the fall or spring.
“We aren’t the only ones excited about Hulk CA herbicide. The tree nut producers we spoke to clearly understand the importance of adding a new active ingredient to their weed control arsenal,” said Daniel Abruzzini, coastal district market development specialist with Corteva Agriscience. “Hulk CA herbicide brings excellent efficacy for reliable control of tough Conyza broadleaf weeds such as hairy fleabane and horseweed.”
Hulk® CA herbicide with Rinskor® active can be applied when the crop is dormant or nondormant, extending the window of application flexibility. This allows Hulk CA herbicide to be added to weed control programs and used year-round.
“Hulk CA herbicide features an active ingredient different from glyphosate, glufosinate and PPO inhibitors, which are frequently used in tree crop production,” Abruzzini said. “It also has a favorable environmental profile. The U.S. Environmental Protection Agency has classified Rinskor active as a reduced-risk herbicide.”
Cleaner orchard floors allow growers to more easily operate irrigation and fertilizer equipment and maximize harvest efficiency. Put Hulk CA herbicide with Rinskor active in your tree nut program, control troublesome broadleaf weeds and share in the success other California orchard managers are having with Hulk CA herbicide.
For more information, visit Corteva.us/HulkCA or contact your local Corteva Agriscience representative.
As if California growers and PCAs didn’t have enough on their plates with rising input costs compounded by the most restrictive laws & regulations in the nation, they’ve been further challenged with an unusual pest problem this year — rats! An increasing number of abandoned orchards and vineyards due to poor economic circumstances has caused a feeding frenzy for some uninvited rodent guests, whose numbers have been multiplying at unprecedented levels. Ruthann Anderson, President/CEO of the California Association of Pest Control Advisers (CAPCA), met with Matthew Malcolm on California Ag Network to explain this issue and what they are doing to help provide the tools and resources growers and PCAs to combat this emergency situation, beginning with an anonymous survey they can fill out HERE. Watch this brief video to learn more.
Shield your yield with Tidal Grow® Spectra™, a bioactive fungicide, bactericide, and nematicide that’s now approved for California growers. Spectra™ fights pests and pathogens directly, enhances natural crop defenses, and fortifies against abiotic stressors. It also boosts nutrient uptake, root function, growth, and yield while working synergistically with other active ingredients.
Growers are effectively fighting California crop threats like Almond Blossom Blight, Shot Hole, and Powdery Mildew with Spectra™. In fact, in a 2023 almond trial, Spectra™ provided a 15% reduction of Shot Hole over Grower Standard while also helping offset its cost by enabling reduced use of the Grower Standard fungicide.
Protect your crops and shield your yield with Spectra™. Click the button below to learn more.
California’s Central Valley is a land of agricultural abundance, known for its incredible diversity of crops including fruits, vegetables and nuts. It produces approximately 25% of the nation’s food.
But with plenty can come pests – in as many varieties and types as the crops grown in the region. Area farmers have worked with USDA’s Natural Resources Conservation Service (NRCS) to implement integrated pest management into their orchard operations with marked results.
Sandra and Mike Smith of Smith Family Farm in Fresno, California, showed NRCS Chief Aubrey Bettencourt the benefits of the practices that they have incorporated with NRCS assistance as they toured their 36-acre almond orchard.
Established in 1903, the farm is on the cusp of welcoming its fifth generation of farmers. By adapting their operations to increase conservation and sustainability practices, the Smiths hope to pass on a rich legacy to their young granddaughters.
The Smiths highlighted the impact that integrated pest management practices – notably hormone disruptors – have had in their fight to combat navel orangeworms in their almond orchards.
“We were at 17.1% loss of our almond crop two years ago because of the infestation of navel orangeworms,” Mike Smith told Chief Bettencourt. “Once we implemented the mating disrupters, we were able to bring our almond reject numbers down to 1.1%.”
Navel orangeworms burrow into almond nuts to feed on the kernel, damaging the nut and impacting producers’ overall yield and harvest quality. Deploying pheromone-based mating disruption tools can reduce navel orangeworm populations by hindering male moths’ ability to locate females.
The Smiths have also leaned on NRCS technical assistance to implement other conservation techniques to increase the health of their orchard. The family now prioritizes composting and increasing organic matter, guided by the knowledge gained through NRCS collaboration.
Further north, Chinchiolo Farming Co., Inc., a family-run business located in Lodi, California, is managing orchards of a different kind while embracing similar production practices.
Producer James Patrick Chinchiolo has worked to uphold a century-old farming legacy, started by great grandfather Italian immigrant James Joseph Chinchiolo. Chinchiolo has worked with NRCS to incorporate a number of conservation practices including cover crops, tractor replacements, orchard removal and soil incorporation.
Like the Smiths, Chinchiolo has dealt with pest issues, incorporating a Biologically Integrated Orchard Systems (BIOS) approach in managing his orchards. The BIOS system aligns with NRCS principles, embracing the implementation of conservation practices like cover cropping, beneficial insect habitat, and compost application to keep pests at bay.
“We aim to foster a more ecologically balanced environment within our orchards,” Chinchiolo said during his discussion with Chief Bettencourt. “We are focusing on minimizing our inputs and creating more habitat for beneficial insects to flourish to help control unwanted pests.”
Conservation practices like cover cropping and compost application not only help pollinators flourish – a crucial part of growing beautiful cherries – they also protect the trees’ overall health, improving soil structure and water retention.
After last summer’s heat impacted this year’s cherry crop, Chinchiolo is working to take additional measures to make his trees more heat resistant in preparation for next season.
“Growing cherries is never predictable. But it’s always beautiful.” Chinchiolo said.
Helping People Help the Land
During her visit, Chief Bettencourt emphasized that the agency’s primary focus is to give producers the tools that they need to be the best producers that they can be – increasing their yield while stewarding the nation’s natural resources.
“Producers are the solution, and we want to empower them by getting our highly skilled staff out in the field to provide technical support. We want to streamline our programs to work better and faster for producers,” she said.
NRCS helps farmers, ranchers and forest landowners make critical investments in their operations and local communities by helping them implement proven practices to ensure all of America’s farms, ranches and private lands are economically viable and thriving.
If you are interested learning how these programs can help you achieve your operational and land management goals, find your local USDA Service Center and get started today.
Follow the Chief through our blog series as she meets with producers across the country to learn how NRCS has helped their operations. — By Debra Denhart, Public Affairs Specialist, USDA
Improving Tree Nut Crop Management Through Effective Weed Control
Preventing Broadleaf Weeds from Obstructing Orchard Floors
In sports, there is nothing like good competition. When it comes to managing orchard floors, competition can be a nightmare, especially when that competition comes from tough-to-control broadleaf weeds.
A weed-free orchard floor is more than visually appealing; it sets the stage for better orchard management throughout the season and improved efficiency at harvest.
Early Control
Tree nut production is challenging enough without having to worry about controlling tough Conyza broadleaf weeds such as hairy fleabane and horseweed, along with other species like prickly lettuce, mallow and filaree. If a herbicide used in a weed control program provides only partial control, regrowth is likely.
“Timing herbicide applications when broadleaf weeds are small is always advised,” said Daniel Abruzzini, Coastal District market development specialist with Corteva Agriscience. “Small, actively growing weeds absorb and more readily transport herbicides throughout the plant than larger weeds. Susceptibility is greater when weeds are small — which increases the chances for control.”
At all costs, prevent weeds from reaching the reproductive stage and heading out, which adds to next year’s seedbank. A single horseweed plant can produce up to 250,000 seeds. Hulk® CA herbicide with Rinskor® active is a new and effective Group 4 herbicide offering excellent broadleaf control. Through systemic activity, it controls emerged, susceptible weeds and prevents regrowth.
“This innovative herbicide provides tree nut crop growers with a powerful new solution to manage challenging broadleaf weeds in permanent crops,” Abruzzini said. “Hulk CA herbicide delivers a flexible solution as part of a season-long weed management program and can be used alone or with a tank-mix partner. It also is compatible as part of a preemergence or burndown program in the fall or spring.”
Flexibility
Like weed control in row crops, effective weed management in tree nut orchards should begin early and continue through fruit set and nut development. That creates the need for a herbicide with extended flexibility, not only in application timing but also in tank-mix compatibility. More orchard managers are finding those attributes in Hulk CA herbicide with Rinskor active.
Hulk CA with Rinskor active offers a broad application window for both dormant and non-dormant uses.
For more information, visit Corteva.us/HulkCA or your local Corteva Agriscience representative.
California almond growers are facing an unprecedented challenge this season as a severe roof rat infestation sweeps through orchards across the Southern and Western San Joaquin Valley. An early survey indicates the outbreak has impacted well over 100,000 acres, a number that has likely grown, causing widespread damage and significant economic losses.
What the Almond Board of California Has Learned
Almond growers across Merced, Fresno, Kings, and Kern counties have reported an alarming spike in rodent populations. Over the last several months, ABC has participated in tours and meetings about the severity of this rat infestation, and field observations indicate that these rodents are using irrigation canals and other waterways as corridors, enabling them to rapidly spread between orchards and diverse agricultural fields. This mobility is exacerbating the extent of damage and complicating containment efforts.
Roof rats are arboreal, meaning they spend a considerable amount of their life above ground, often building nests in trees. However, for several years, researchers have noted that in almonds and other tree nuts, they use burrows extensively.Although it’s undetermined as to why, some believe it’s the lack of cover in the winter months that drives this behavior.
According to preliminary findings from a CDFA-led surveyconducted in the fall of 2024, monitoring efforts revealed particularly high densities of rats in the reported areas, with up to 32 rats captured per night at some locations. Direct damage to the trees occurs through consumption of nuts, girdling of small and large limbs, and burrowing in the root zone. Additionally, damage to irrigation systems, equipment and other infrastructure within orchards is often greater than direct crop loss.
Economic analyses from the CDFA report estimated total on-farm losses ranging from $109 million to $311 million. Major expenses contributing to these figures included drip line replacements, which alone accounted for losses between $56 million and $168 million, and yield losses resulting from disrupted post-harvest irrigation, estimated at $43 million to $129 million. Additional significant costs stemmed from direct tree damage, farm equipment repairs, machinery cleaning due to rodent contamination and replacement of damaged trees.
The lower-end estimates assumed less extensive damage, such as 25% of affected acreage needing drip line replacement and 10% tree damage. Conversely, the higher-end scenario accounted for more severe conditions, including drip line replacements on 75% of impacted acreage, 15% tree damage, and substantial farm equipment repairs and maintenance.
Photo Caption: Irrigation line damage from rats
Drip line damage and yield reductions alone represented nearly 90% of the anticipated financial impact. Furthermore, CDFA cautions that these numbers may underestimate the true financial burden, as broader impacts, including newly planted orchards and extensive post-harvest cleanup beyond farm machinery, were not fully quantified in the preliminary analysis.
During ABC’s learnings, one grower noted the replacement of an entire drip irrigation system was estimated at $20,000, and the rodents also chewed through irrigation wiring causing fires. A second almond grower detailed extreme damage that was estimated at a 50% crop loss, even while he was exterminating between 50-100 rats a day.
Photo Caption: Aside from equipment and tree damage, rats are eating the nuts themselves on the tree.
UC ANR’s IPM Recommendations
Farm managers, PCAs, and growers are expressing growing frustration and concern over their ability to sustain operations. Management strategies currently in use include bait stations and aluminum phosphide treatments of burrows in the winter, and less conventional methods such as snap traps, owl boxes and applying carbon monoxide or carbon dioxide into burrows as another fumigation option. However, many growers report these tactics are labor-intensive, costly, and insufficient for the scale of this infestation. Additionally, growers noted that rotating bait flavors has become necessary as rodents quickly grow wary and “bait shy.”
Based on research led by UC ANR scientists Niamh Quinn and Roger Baldwin, growers are advised to implement a comprehensive Integrated Pest Management (IPM) strategy tailored specifically to roof rat behavior in tree nut orchard environments. The cornerstone of effective IPM is rigorous monitoring with the use of tracking tunnels and ink cards. Strategically placed game cameras can pinpoint rat activity hotspots, while also providing information on how rat numbers are changing over time.
Using that information, growers can then implement targeted baiting programs. Elevated bait stations containing diphacinone-treated oats, positioned every 165 feet, align with roof rats’ natural climbing behavior while minimizing risks to non-target species. For tree nuts, bait stations strategically placed on the ground could also help, although this application is limited to dormant seasons. To have a significant impact, growers must keep stations full of fresh bait over a period of about four weeks. In situations where rat densities are very high, a longer period may be needed.
Again, monitoring is important during the bait program period and growers should stop the program when bait consumption becomes minimal. As a reminder, rodenticide regulations are ever-changing, and applicators should always read the label carefully to ensure compliance.
Strategically placed snap traps in protective trapping tunnels, spaced approximately 245 feet apart, form a crucial component of long-term rat control post-baiting. Regular maintenance and monitoring of these traps are necessary to sustain effectiveness. Collaboration among neighboring orchards can further enhance the efficacy of these integrated pest management measures.
During the dormant season, broadcasting zinc phosphide bait or applying zinc phosphide within burrows is also an option, although the efficacy of this bait for rats in California orchards is unknown. Burrow fumigation with aluminum phosphide, gas cartridges or carbon monoxide and carbon dioxide injection devices are also options. UC ANR advises growers to be aware that if using aluminum phosphide, in addition to normal requirements that apply to all restricted-use fumigants, you also now need to have a Burrowing Vertebrate Pest Fumigation Certificate (PCA license) to use this product.Also note that any diphacinone-treated bait for use in bait stations must be bought from a County Ag Commissioner’s office.
Based on the level of infestation learned from using the tracking tools, multiple overlapping strategies may be necessary to reduce the populations.And if possible, rotating to a non-diphacinone option is a good decision to avoid diphacinone-resistance.
Additional Support and Resources on the Horizon
Industry groups are mobilizing to provide tangible support for growers facing ongoing rodent pressures. CAPCA, in collaboration with the Almond Board of California and other agricultural partners, is pooling funds to purchase and distribute abatement stations or owl boxes to affected regions, depending on CDFA recommendations.
Additionally, CDFA is actively working to facilitate updates to pesticide labels for rodent control materials. Specifically, updates and approvals for the use of zinc phosphide and diphacinone are in progress, which could expand application options for growers if finalized. These advancements would provide growers with additional chemical tools to integrate into their rodent management programs.
Furthermore, the latest information and assistance opportunities are being planned for informative sessions at the 51st Annual CAPCA Conference in October and The Almond Conference in December. UC Cooperative Extension’s Roger Baldwin will be presenting Monday, October 20, at the annual CAPCA conference in Reno, Nevada. ABC’s Gabriele Ludwig will be leading a discussion about rodent control in the face of changing regulations at The Almond Conference December 10-12 in Sacramento, CA. — By the Almond Board of California
How one California almond grower managed over-soaked orchards to prevent devastating soilborne pathogens.
BY BETHANY MACON
Losing crops is a reality of farming, especially when you’re battling weather, new pests and emerging diseases. Seeing a few acres of your life’s work perish is tough, but the threat of losing your entire operation is a different type of sting. One California almond grower shares how soil health improvements made his orchards vulnerable to disease and how he was able to bring them back from the brink of total devastation.
Trees Lost to Unusually Wet Weather Worsened by Soil Prep
Whole orchard recycling is a process to reincorporate an outgoing orchard in preparation for planting a new one. Mature trees are felled and ground into woodchips, which are then spread and incorporated into the soil. The University of California found that this process can help improve water retention. The issue for John Fassler, a California pest advisor who went through whole orchard recycling, was that the moist soil and greater-than-normal rainfall turned his orchards into the perfect breeding ground for oomycete pathogens like Phytophthora.
Fassler has consulted at Braden Farms where they used whole orchard recycling as a way to prepare for planting a new orchard. “This is a fairly new process, which means we’re learning as we go,” he says. “Some issues we’ve seen have been a rise in fungal diseases, such as Phytophthora and other replant diseases.”
Mother Nature hasn’t helped the fungal disease risk, especially at the beginning of the 2023 growing season. California experienced greater than average annual precipitation in 2023, breaking numerous records and ending three years of persistent drought, according to the California Nevada River Forecast Center.
“We’ve had significant rainfall in California the last two years, so this has really intensified the battle with Phytophthora in some spots,” says Ashley Bandoni, Syngenta sales representative and California almond grower.
Fassler experienced devastation due to those heavy rains. One of his orchards was completely submerged, worsening the orchard’s Phytophthora issues.
“We lost about 500 trees on this block due to Phytophthora and replant disease,” says Fassler. “Phytophthora is becoming more and more of an issue in these wetter years.”
Phytophthora Overtakes Young Almond Trees
Many California growers and crop consultants have been battling fungal disease challenges.
Ethan Nicol, an independent pest control advisor and crop consultant for Balanced Agronomics, helped one of his customers manage extreme Phytophthora in a young almond orchard.
Planted in the fall of 2021, Nicol began seeing early symptoms of Phytophthora infections the following spring. Young trees like the ones in the orchard Nicol manages tend to be more susceptible to disease because their root systems and crown areas are smaller compared to those of mature trees, according to the University of California Department of Agriculture.
“In that first 2022 season, we observed maybe 30 percent of the orchard was infected,” says Nicol. “By mid-August, we had really grown to realize the significance of the issue.”
Coming Back from Orchard Devastation
For both Nicol and Fassler, almond yield potential was on the line and devastation was just over the horizon. They both had a tough decision to make.
“As far as doing our research going into it, usually we have the Syngenta reps come in to help us decide if the product will be a good fit for us,” says Fassler. “We also ask about how the product differentiates itself from what we’ve already been doing.”
After discussions with their local Syngenta experts, Fassler and Nicol decided to apply Orondis®fungicide to help save their orchards. Fassler says his flooded orchard plot turned around.
“My experience with Orondis changed up our program,” says Fassler. “We’ve been able to work it into our program really well and we didn’t lose one tree this year.”
Nicol’s experience with Orondis was also nothing short of extraordinary. Before application, Nicol was working with the grower to continuously remove and replant dead trees. They lost roughly 600 almond trees — six ranches — to Phytophthora. Once Orondis was applied in 2023, Nicol observed a noticeable decline in newly infected trees.
[quotes quotes_style=”bpull” quotes_pos=”center”] My experience with Orondis changed up our program. We’ve been able to work it into our program really well and we didn’t lose one tree this year. —John Fassler, California Pest Advisor [/quotes]
“We were confident in the success that we were seeing by the replants taking and growing strongly, and the existing trees continuing to grow and not develop signs of Phytophthora,” says Nicol. “Going into 2024, just as a precaution and to help protect this investment, we made an additional Orondis application. There’s been almost no sign of infected trees this season.”
Growers Also Need Care
If Fassler and Nicol didn’t have the guidance and support of their Syngenta representatives, their almond orchards might have been lost.
“I’ve worked with Syngenta for probably about the last 20 years, and through the years we’ve had many different experiences,” says Fassler. “Syngenta has always been there to help us through and guide us through what needed to be done.”
