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Monitoring Citrus Mealybug in California’s Central Valley: A Key to Developing Informed Management

By
Sandipa Gautam, Ph.D., | Area Citrus IPM Advisor, Fresno, Madera, Tulare and Kern Counties
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Figure 1. Citrus mealybug adult female with egg sac. Amber colored eggs are loosely held by cottony flint (all photos courtesy S. Gautam.)

Citrus mealybug, Planococcus citri, has become an increasing concern for citrus growers in California. This pest feeds on plant sap on all parts of plants, including flush, twig and fruits, reducing tree vigor and affecting yield. Mealybug produces copious amounts of honeydew while feeding, which is discharged on leaf and fruit surfaces where sooty mold grows. Mealybug infestations may also lead to serious ant invasions as sugar-feeding ants tend mealybugs and protect them from natural enemies, interfering with biocontrol efforts. Regular, early season monitoring is essential for detecting initial infestations and implementing timely control measures.

Citrus mealybugs are soft, oval, flat, distinctly segmented insects covered with white mealy wax, giving them a dusted-in-flour appearance. Females lay eggs in egg sacs loosely held by white cottony flint (Fig. 1). Crawlers, when hatched, are yellowish in color but soon develop a waxy covering once they start feeding. Adult females are 3 to 5 mm long and wingless with pinkish bodies covered in white mealy wax. Males are winged and take a longer time to develop than females.

California’s Central Valley has approximately 75% of the state’s citrus production acreage. Mealybugs are increasingly becoming a difficult pest to manage and are expanding in acreage and have been reported in all citrus varieties grown in the Central Valley. Mealybugs are not only a direct pest that causes yield and cosmetic damage to fruit but also a phytosanitary concern for exports to markets such as Korea, China and Australia, where zero-tolerance policies apply.

Effective monitoring of mealybug enables:
• Early detection to prevent population outbreaks
• Timely control decisions, reducing overall pesticide usage
• Accurate pest history tracking for developing long-term sustainable management methods

When to Monitor?
Monitoring should begin in early spring (March/April) and continue through postharvest (November to March). While mealybugs are most active during summer and fall, warm microclimates in orchards can support winter reproduction, especially if average daily temperatures stay around 60 degrees F.

What to Monitor and How?
Mealybug overwinters as adults and eggs (within the egg sacs). Early in the season, look for mealybug egg sacs/adults inside the tree canopy on trunk and inner branches or between fruits. Use a hand lens to inspect for crawlers and first instars. They intersperse via wind, or by ants, birds or equipment. As the season progresses, mealybug moves to young fruit and infests fruit.

Early season (January to March)
• Mealybugs overwinter as adult females and eggs.
• Focus monitoring in protected areas (e.g., deep canopy, bark crevices, inside fruit clusters).
• Use a hand lens to inspect for egg sacs and first instars.

Spring to early summer (April to June)
• Crawlers hatch and begin dispersing via wind, ants or machinery.
• Monitor trunk, scaffold limbs and new flush for early populations.
• Begin pheromone trapping for male activity.

Summer to fall (July to December)
• Populations move onto developing fruit.
• Mealybugs feed on calyx and peduncle, sometimes clustering around fruit stems.
• In high-pressure areas, they may spread across the entire fruit surface.
• Multiple overlapping generations may be present by fall.

Pheromone trapping: a valuable tool
For early detection, especially in orchards with no
known infestation:
• Install pheromone trap cards (Fig. 2) in mid-canopy
(one trap per 10 acres).
• Begin trapping in April and replace lures every five weeks.
• Interpret with caution as catches may reflect nearby orchard activity as well as local emergence.

Figure 2. Citrus mealybug trap card with a septa lure.

Hotspots to monitor
• Ant activity zones: Ants often lead to hidden mealybug clusters.
• Wind machines: Areas beneath may harbor infestations due to insect dispersal.
• Previously infested trees: Key indicators of localized reinfestation.

If your orchard currently does not have citrus mealybug, it may be difficult to determine where infestation starts. In that scenario, you can do the following:

Use a pheromone lure and a trap card to monitor for citrus mealybug males, one card in the middle of the orchard per 10 acres. Change lures every five weeks. Begin monitoring in April (Fig. 2). Be mindful because flyers may come from nearby orchards.

‘Mealybug infestations may also lead to serious ant invasions… interfering with biocontrol efforts.’

Check any areas with ant activity near the wind machines for any signs of mealybug activity as ants and birds can carry and relocate citrus mealybug.

If your orchard has a history of infestation, it is a good idea to begin monitoring those previously infested trees. Because mealybugs move to different parts of the plants as the season progresses, monitoring is season-dependent.

Figure 3. Citrus mealybug males on trap cards shows that the activity in the season started in early April. Currently, second-generation males have started flying.

What is Happening with Citrus Mealybug Populations in The Central Valley?
Recent monitoring across five
Central Valley orchards provides
the following insights:
• First male flights: Detected in early April, peaking by the third week of April (Fig. 3).
• Current (mid-June) population: Dominated by egg-laying females on fruit peduncles and inner canopy branches (Figs. 4 and 5).
• Second-generation male flight: Now beginning. We have started catching males on the traps. Adult and egg-producing females are present as of June 9, 2025.

Figure 4. Citrus mealybug adult at the arrowhead. Photo taken April 30, 2025.
Figure 5. Citrus mealybug adults on fruit peduncle. Also note ants near mealybug. Photo taken June 9, 2025.

Citrus mealybug has become an increasingly complex pest of citrus in California’s Central Valley, with implications for tree health, fruit marketability and yield loss. A seasonally adjusted, site-specific monitoring plan can be helpful in staying ahead of population growth and ensuring effective, reduced-risk pest management.

Incorporating Biofungicides in Fungicide Rotation for Powdery Mildew Control: Why, How and What to Consider

By
Tian Tian | UCCE Viticulture Farm Advisor, Kern County
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Rotational and tank-mix programs incorporating biofungicides demonstrated comparable powdery mildew control to conventional synthetic-only treatments under moderate disease pressure (all photos by T. Tian.)

The sulfury smell on our shirts in the spring signals a new season and the battle with powdery mildew (PM), arguably the most important and expensive disease to control in the vineyard. The causal pathogen, Erysiphe necator, has a high productive rate and short generation time. Since it infects succulent tissues of grapevines, including young shoots, green berries and rachis, preventative practices like fungicide sprays typically begin at bud break and last until veraison or even beyond. Insufficient PM management results in scars on the berry, compromising fruit quality, reducing market value and increasing risks of bunch rot during fruit ripening. Given the large canopy of vines grown in the San Joaquin Valley and favorable weather conditions for PM development, fungicide applications become a must.

Successful PM control relies on effective fungicide rotation and thorough spray coverage. In conventional vineyards, we depend heavily on sulfur and synthetic fungicides. While sulfur is affordable and resistance has not been observed, its residual effects can wear off within five to seven days, requiring frequent applications to keep the vineyard clean. Synthetic fungicides, on the other hand, convey benefits of high efficacy and long residual effects. However, their site-specific modes of action increase the risk of resistance with repeated use of the same active ingredient. Widespread resistance of FRAC 11 fungicides (QoIs) in PM has been confirmed in California vineyards, particularly in table grapes. The resistance of FRAC 3 (DMIs) is often suspected, though we still lack sensitive and reliable molecular methods to quickly confirm field observations. Note that poor spray coverage accelerates resistance development because fungi that survive the sublethal exposure have a greater chance to develop natural tolerance and genetic mutations.

In addition to sulfur and synthetic fungicides, biofungicides became popular in the last few decades. Though they have mainly been used in organic systems, there is increasing interest in adopting biofungicides for PM control in conventional vineyards, aligning with California Department of Pesticide Regulation’s Sustainable Pest Management Roadmap for California. Biofungicides can be roughly separated into four categories: plant extracts and oils, mineral-based oils and compounds, bacterial or fungal strains, and metabolites of fungi or bacteria. Compared to synthetic fungicides, they offer shorter reentry and preharvest intervals. They are subject to a lower risk of resistance development, owing to their diverse mechanisms. While their residual activity is generally shorter, biofungicides are ideal complementary tools in conventional programs for enhanced disease control and resistance management.

While their residual activity is generally shorter, biofungicides are ideal complementary tools in conventional programs for enhanced disease control and resistance management.

Results from Field Trials (2022-24)
From 2022 to 2024, we examined the efficacy of incorporating biofungicides into PM control in table grape vineyards. These trials involved rotating or tank-mixing biofungicides with synthetic fungicides applied between bloom and two weeks post-veraison. The efficacy of those programs was compared to a conventional synthetic program that used wettable sulfur, sulfur dust, copper and mineral oils prior to bloom, and synthetic fungicides afterward. All fungicides were used at label rates. The incidence and severity of PM in clusters were evaluated pre-veraison and at veraison.

Trial 1: Plant extract rotation
In the first trial, a plant extract-based product was integrated into a synthetic fungicide rotation. The conventional synthetic program involved pre-bloom applications of wettable sulfur followed by rotational applications of Luna Experience (fluopyram + tebuconazole), Switch (cyprodinil), Vivando (metrafenone) and Torino (cyflufenamid) every 14 days between bloom and veraison. In the other treatment, Problad Verde (Banda de Lupinus doce), a plant extract product, was applied at bloom and veraison to replace synthetic fungicides without changing the spray interval. Both programs demonstrated comparable efficacy in reducing PM incidence and severity in a Flame Seedless vineyard under moderate disease pressure (Fig. 1).

Figure 1. The efficacy of two fungicide program on powdery mildew control in a Flame seedless vineyard in 2022. The control vines were not sprayed after bloom. The incidence and severity of powdery mildew in clusters were evaluated at veraison.

Trial 2: Bacillus-based rotation
The second trial evaluated the rotation of Bacillus-based products with synthetic fungicides. The conventional synthetic program utilized copper, sulfur and mineral oils pre-bloom, followed by a 14-day rotational schedule of Luna Experience, Switch, Vivando and Elevate 50 WDG (fenhexamid). In the other treatment, synthetic fungicides were replaced by Double Nickel (Bacillus amyloliquefaciens) and Aviv (Bacillus subtilis) at bloom, bunch closure and veraison. Considering the potentially shorter residual activity of the Bacillus products, the spray interval for this treatment was reduced to seven days (e.g., Switch applied seven days after Double Nickel at bloom). Compared to the conventional program, adding Double Nickel and Aviv to the rotation offered a small improvement in PM control (Fig. 2). It may be associated with the additional spray in the second treatment. Thus, in the second year of the experiment, we tested a similar program but kept the spray interval the same for both treatments. Results suggested comparable PM control efficacy between those two programs (Fig. 2).

Figure 2. The efficacy of two fungicide programs on powdery mildew control in a Thompson seedless vineyard in 2023 (first year) and 2024 (second year). The control vines were not sprayed after bloom. The incidence and severity of powdery mildew in clusters were evaluated at veraison in the first year. In the second year, additional evaluation was conducted two weeks prior to veraison (pre-veraison).

Additional tank-mix trials
In the two other trials,  one or two fungicides, including Oxidate 5.0 (hydrogen peroxide and peroxyacetic acid), Cinnerate (cinnamon oil and potassium oleate) and Instill O (copper sulfate pentahydrate), along with Avivand Double Nickel, were tank-mixed with synthetic fungicides in each spray. The spray interval was every 14 to 21 days between bloom and veraison. These tank-mix programs demonstrated comparable efficacy in reducing PM incidence and severity to the conventional synthetic program. No phytotoxicity was observed. However, these findings are preliminary. The viability of Bacillus bacteria in specific tank mixes with synthetic fungicides as well as potential phytotoxicity issues requires further investigation.

Overall, our findings suggest incorporating biofungicides into conventional fungicide programs, either through rotation or tank mixing, can achieve similar PM control efficacy as programs relying solely on synthetic fungicides post-bloom. Integrating fungicides with complementary mechanisms may offer benefits, such as reducing the risk of fungicide resistance development and providing greater flexibility in preharvest fungicide applications. We are continuing our research and looking forward to providing the industry with updated information on effective PM management strategies.

The author would like to thank Consolidated Central Valley Table Grape Pest and Disease Control District and industry collaborators for funding support. 

Discussion of research findings necessitates using trade names. This does not constitute product endorsement, nor does it suggest products not listed would not be suitable for use. Some research results involve use of chemicals which are currently registered for use or may involve use which would be considered out of label. These results are reported but are not recommended by UC for use. Consult the label and use it as the basis of all recommendations.

How Living Algae is Transforming Sustainable Agriculture: The Chlorella vulgaris Breakthrough

By
Dr. George Taylor | EnSoil Algae
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How Living Algae is Transforming Sustainable Agriculture: The Chlorella vulgaris Breakthrough

Soil is the source and catalyst for all life-nourishing substances that plant and animal life need for sustenance, and the more life in soil, the better crops and animals who consume them will thrive.

The use of biostimulants in agriculture has gained significant traction due to their potential to enhance yields, improve soil health and reduce dependency on chemical fertilizers. Biostimulants like humic and fulvic acids, protein hydrolysates, compost and inoculants, and kelp or seaweed extracts have surged in usage across all crop types and continents. Research proves that all of them bring some benefits, but none of them deliver all the known benefits derived by biostimulants since extensive research began in the 1970s, except for one: live cell green algae, namely Chlorella vulgaris, literally Latin for “common green.”

Chlorella vulgaris is the most ubiquitous freshwater algae found globally, and there is evidence that it was used by ancient cultures in Africa, Mesoamerica and Asia to increase crop production because growers knew that increased fertility would occur by planting near freshwater river deltas and lakes after flooding events.

Microscope image of Chlorella vulgaris, photo courtesy of Andrew Shuler, Enlighted Soil Corp.

These living green microscopic organisms, capable of surviving in soil, are a building block of life and what sets this biostimulant apart from all others because it stimulates the biology that is already in soil.

Extensive research worldwide and field trials have proven that this is of paramount importance in the potency and efficacy of biologicals for significantly boosting soil organic matter (SOM) and microbial biomass, enabling every scientifically recognized benefit attributable to biostimulants to be realized:

  • Improved SOM, plant fertility and microbial mass
  • Increased leaf chlorophyll content resulting in increased photosynthetic capacity
  • Enhanced plant growth and increased yield across a wide variety of crops
  • Reduced dependence on chemical fertilizers (NPK)
  • Enhanced plant resistance to abiotic stresses such as drought, heat and salinity
  • Potential increased resistance to plant pathogens due to improved plant vigor

Soil biodiversity is the key to improving nutrient cycling and plant fertility for increasing productivity while saving on inputs and increasing profits. Published research has shown live green algae, uniquely Chlorella vulgaris, to be a particularly effective biostimulant, having a significant impact on soil microbial activity, plant growth and overall farm ROI.

A Breakthrough in Living Biostimulant Technology

Historically, the challenge of maintaining live algae viability during storage and transport has hindered their widespread use. Green algae, like most plants, are usually dependent on photosynthesis to maintain life. They die when placed in dark storage.

Living organisms feed themselves in one of two ways: producing their own food via photosynthesis, like green plants and algae, or by finding it outside of themselves, like animals and bacteria. Those that photosynthesize are called autotrophs (auto = self, troph = feeding), while those organisms that scavenge or hunt for food are called heterotrophs (hetero = other). There is a third category known as mixotrophic, an organism that can switch between autotrophic and heterotrophic metabolism.

Scientists with EnSoil Algae™ have now introduced a breakthrough formulation of mixotrophic Chlorella vulgaris, which can photosynthesize in light and consume organic material in darkness. This allows them to remain viable during transport and storage for 6 to 12 months. This patent-pending technology does not use any commercial or laboratory gene-altering techniques. It does not rely on genetic modification, as the heterotrophic pathway is already present in green algae. This technology activates that pathway to produce mixotrophic chlorella.

Moreover, live cell green algae is an endophyte acting as a transport vehicle for soil microbes and chlorophyll. A research study by Dr. James White of Rutgers University demonstrated a symbiotic relationship between EnSoil Algae™, plants and endophytic soil bacteria. Algae cells attract and carry bacteria into plant roots, delivering chlorophyll and promoting growth of root hairs.

Reducing Synthetic NPK, Increasing Yields and Crop Quality

One of the most important benefits of living green algae is that it can be used to lower synthetic nitrogen inputs. “Where will the nitrogen come from,” people ask? The answer is that living green algae amplifies nature’s process of extracting nitrogen from the air and converting it into ammonium compounds in the soil. One gram of healthy soil contains some 10 billion bacteria, fungi and other organisms that work together to make this conversion. Live cell green algae accelerate the process of nitrogen fixation.

In addition, rhizospheric bacteria produce weak acids that solubilize soil-bound phosphorus, making it available to plant root systems. This especially happens when these bacteria are stimulated by Chlorella vulgaris. Soil testing using the Haney Soil Test after the first application has even demonstrated excess nitrogen after harvesting, nitrogen that is available for the next season.

Squash in field, photo courtesy of Clemson University

This means growers can reduce their use of synthetic NPK fertilizers to produce quality crops with higher nutrient density. Known as phytochemicals, such as carotenoids, polyphenols and alkaloids, these nutrients are critical for healthy function of organs, strengthening the immune system and preventing chronic disease.

And because EnSoil Algae™ is applied at lower rates and at a much lower cost than synthetic NPK, growers can realize savings of 20% to 50% in fertilizer costs. This enables them to increase their profitability in year one while improving the health of their soil, increasing yields and improving the nutritional content of their crops.

Biostimulants like Chlorella vulgaris make sense because they can lead to significantly improved agronomic and economic outcomes. They enable growers to realize a much better return on investment that compounds over time as increased SOM and organic nutrient cycling improve water retention, plant health and resiliency. This allows for reduction in irrigation and crop protection inputs.

To learn more, download the 72-page Growers Report with research data and trials across a wide variety of crop types, soils and regions. Or come meet Jessica Murison, jessica@ensoilalgae.com at the Progressive Crop Consultant Conference in Visalia, September 24th and 25th.

EnSoil Algae™ is a product of Enlightened Soil Corp., a South Carolina public benefit corporation, ensoilalgae.com.

Thinking About Smarter Irrigation Strategies for California Avocados

By
Taylor Chalstrom
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New irrigation calculators based on local weather data aim to simplify water scheduling for California avocado growers seeking to boost efficiency (photo by Ali Montazar, UCCE.)

At the recent UCCE Avocado Irrigation Workshop in San Diego County, industry experts, crop consultants and growers gathered to address one of the most pressing challenges in avocado farming: irrigation efficiency. The meeting presented Danny Klittich of Mission Produce Inc. shared firsthand insights from groves across the state, highlighting common issues and emerging solutions as well as opportunities for crop consultants to assist growers.

“I think one of the biggest challenges in avocado growing is water management,” Klittich said, “and trying to manage how many hours are applied and the frequency with which it is applied, and then doing that without the tools in the field to have any feedback is difficult.”

He noted many growers are still making irrigation decisions based on rigid routines rather than real-time data. “[Some growers are] just doing six hours twice a week or 24 hours once a week, and not having some type of soil moisture sensor or tree sensor to really have feedback. Is it too much? Is it not enough?”

New Tools for Growers

To address these pain points, new tools and resources are being developed to help growers simplify their decision-making and become more precise.

“The California Avocado Commission is funding a project with Cooperative Extension to build out a simple irrigation calculator based on weather data to give a better estimate for people,” Klittich said. “So they can know how many hours they need to irrigate without having to go do all the math, pulling data out of CIMIS, trying to figure out what all the different correction factors and things are. Just really simplifying things.”

In addition to this calculator, he mentioned ongoing efforts to improve crop coefficients and other input variables that influence irrigation calculations. “I think that’s really where we’ve doubled down.”

For growers ready to invest more deeply, Klittich pointed to the availability of more advanced platforms. “There are so many great paid services that incorporate multiple-sensor packages, where you can purchase multiple sensors and then utilize those for making crop decisions.”

Understanding Soil’s Role

Klittich also emphasized how soil characteristics complicate irrigation planning. “Soil has an obvious interaction with irrigation. It’s how much water we can hold in the root zone. But also, there are innate problems with soil, with limiting layers and percolation rates. All of those have to be taken into account when we’re designing our irrigation management plan.”

Importantly, he clarified water use doesn’t necessarily change with soil type. What changes is how much water the soil can store. “A healthy tree on sandy soil and a healthy tree on heavy soil use the same amount of water. The problem is we can just hold less water in the sand than we can in the heavy soil.”

Actionable Recommendations

For consultants advising growers on next steps, Klittich’s advice is straightforward: Start with basic feedback tools.

“If you don’t have any soil moisture sensing technology, there’s huge return on investment to having just one sensor in the field to tell you if the soil’s too wet or too dry and how deep your irrigations are going,” he said. “I think that is a must in every operation.”

He also encouraged growers to make use of existing public data. “Every grower has access to the CIMIS stations that are a California statewide system. However, there’s not always a station close by, but you can use that data to then influence your irrigation calculations.”

Combining those tools can significantly improve accuracy. “Getting an idea from CIMIS of how much you might need to irrigate and then using a soil sensor to make sure that you didn’t irrigate too much or too little can really make a huge difference above just guessing six hours, eight hours, because the weather was what it was last week.”

Check out the full conversation with Klittich in a recent MyAgLife YouTube video.

BioLumic Brings Food-System Pioneers to Scientific Advisory Group, Deepening World-Class Expertise in Light-Programmed Seed Traits

By
Press Release
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BioLumic is a U.S.- and New Zealand-based agricultural biotechnology company using light signaling as a programming language for plants.

Champaign, Illinois – July 15, 2025 – BioLumic, the only agricultural biotechnology company that programs seed traits using light, today announced the appointment of Dr. Howard-Yana Shapiro, distinguished senior fellow at CIFOR-ICRAF, and Dr. Jeremy Hill, chief science & technology officer at Fonterra Co-operative Group Limited, to its Scientific Advisory Group.

Dr. Shapiro and Professor Hill join founding members Professor Mark Tester – internationally renowned for pioneering the science of salt-tolerant crops – and Dr. John Bedbrook, former DuPont Vice President and inventor on more than 50 plant-biotech patents. Together, the four advisors bring a uniquely diverse mix of agronomic and biotechnology discovery for world-leading innovations.

“Bringing on Howard and Jeremy strengthens an advisory team with a proven track record of scaling breakthrough science from lab bench to global impact,” said Steve Sibulkin, CEO of BioLumic. “Their insights will accelerate the impact of our light-signal xTraits™ platform, helping ensure it delivers meaningful value for farmers, industry, and the planet—while advancing a more resilient food system.”

BioLumic’s patented xTraits™ platform delivers precisely timed UV-light signals to activate plants’ own gene-expression pathways. The result is double-digit gains in yield, quality, and resilience in a fraction of the time and cost of conventional trait development, and all without altering DNA. Advanced programs in corn, soybeans, rice, and forage crops are already under way with multiple partners, including food production companies, charitable entities, and leading seed companies.

New Scientific Advisory Group Members:

Dr. Howard-Yana Shapiro is a 50-year crop-science pioneer who led global agriculture initiatives at Mars, Inc., and founded the African Orphan Crops Consortium, which is working to improve 101 nutrient-dense crops critical to food security across Africa. He has driven scientific efforts that combine biodiversity, nutrition, and equitable access to high-performing crops.

“I am excited to support BioLumic’s pioneering work in using light to naturally enhance plant performance,” said Shapiro. “Harnessing the power of biology and light opens up powerful new pathways for crop productivity and resilience traits.”

Professor Jeremy Hill brings decades of experience in science, technology, nutrition and sustainability across the entire farm-to-consumer dairy value chain. As Fonterra’s Chief Science & Technology Officer, and former President of the International Dairy Federation, he helped lead the development of international greenhouse gas and nutrition frameworks for agriculture and food systems. In 2020, Prof. Hill was awarded the Member of the New Zealand Order of Merit for services to the dairy industry and scientific research in the Queen’s Birthday Honours.

“BioLumic’s innovation sits at the nexus of science, sustainability, and food system transformation,” said Hill. “I look forward to contributing to BioLumic’s efforts to shape the future of sustainable agriculture.”

BioLumic’s Scientific Advisory Group brings deep expertise across plant science, trait commercialization, global food systems, and sustainability.

About BioLumic
Founded in 2013, BioLumic is a U.S.- and New Zealand-based agricultural biotechnology company using light signaling as a programming language for plants. Its patented xTraits™ technology unlocks non-GMO genetic expression traits to enhance yield, composition, and crop resilience through a one-time, light-based seed application. BioLumic traits are scalable, fast to develop, and easily integrated into existing seed systems. Learn more at www.biolumic.com or contact info@biolumic.com.

Media Contact
Sara – AgTech PR for BioLumic
sara@agtechpr.com

California Walnut Conference Returns with New Date and Location for 2026

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Press Release
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California Walnut Conference
California Walnut Conference

The California Walnut Conference, the annual gathering for walnut growers and handlers, is returning with a new date and location for 2026. The event will take place February 19, 2026, at the Turlock Fairgrounds, marking a new chapter in its continued evolution and growth.

The annual California Walnut Conference is presented by West Coast Nut magazine in partnership with the California Walnut Commission (CWC). Together, these organizations have built a forum for information, networking, and solutions for walnut growers and handlers and industry suppliers.

“We know this event has become important to the walnut industry and allied community and hope this more centralized location and new date will help make the conference accessible to additional growers and handlers,” said Jason Scott, Publisher and CEO of West Coast Nut and JCS Marketing Inc.

This year’s conference will include a full day of seminars covering topics important to walnut growers and handlers, including research, production practices, trade developments, advocacy, and market dynamics. Continuing education will be offered eligible sessions.

“The California Walnut Conference is a cornerstone of our efforts to bring the industry together,” said Robert Verloop, Executive Director and CEO of the California Walnut Board and Commission. “We changed the location to Turlock in order to make the conference more accessible for all growers.  It provides the opportunity for knowledge-sharing, collaboration, and dialogue that is essential to moving our industry forward into the future. With the challenges and opportunities ahead, this conference helps ensure we are aligned and working toward a strong and sustainable future for California walnuts.”

Based on overwhelming interest from last year, the Poster Board Research Sessions will be expanded in 2026. These sessions feature key findings from walnut industry-funded research in areas such as pest management, irrigation, fertility, varieties and rootstocks, and overall crop production. Researchers will be on hand to engage directly with attendees, answer questions, and provide insights into practical applications for growers.

The Walnut Industry Resource Center—first introduced in 2025—will return with even more nonprofit and government partners offering cost-share programs, educational materials, and grower-focused resources aimed at improving profitability and sustainability on the farm.

Don’t miss this opportunity to connect directly with handlers, processors, and the California Walnut Board and Commission staff to learn more about how the industry is working together to boost demand and increase prices for California walnuts.

Exhibitor and sponsorship registration opens this month. Interested businesses and organizations are encouraged to act quickly to reserve space. For sponsorship or exhibitor opportunities, contact sales@jcsmarketinginc.com.

Attendee registration will also open this month. Growers, handlers, and industry professionals can register at myaglife.com/events.

For more details or to register for this free event, visit myaglife.com/events or walnuts.org.

Get the Ball Rolling on Spider Mites in 2025

By
Taylor Chalstrom | Editor
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An integrated approach to spider mites is always recommended, including the use of beneficial insects, particularly fostering six spotted thrips populations, according to Todd Burkdoll, field market development specialist for Valent (photo courtesy UC Statewide IPM Program.)

As summer temperatures soar into triple digits across California’s Central Valley, the annual battle against spider mites has intensified. Growers with a history of infestations face a high risk once again, prompting early action.

“There’s a 95% chance that orchards that had spider mites last year have them again this year,” said Todd Burkdoll, field market development specialist for Valent. “Scouting for overwintering females, if you find adults out there, they’re laying eggs, and those eggs will hatch, and then it goes from one to two to four exponentially really fast. Get on them early, get those females under control.”

Burkdoll recommends an integrated pest management (IPM) approach that combines vigilance, targeted materials and biological control.

He emphasizes early detection. “When in doubt, scout,” attributing that advice to the late John Palumbo.

For chemical control, Burkdoll favors an insect growth regulator (IGR). “I like to go with an IGR [like] Zeal. It’s very specific. It’s basically a mite growth regulator and sterilizes the females, so the eggs that she lays are sterile. The eggs that are already laid, they turn black and die, and the nymphs don’t go from one to the next. So it’s a pretty effective tool.”

Despite its efficacy, proper application is critical. “The only Achilles heel is you have to get good coverage. You can’t spray and pray, go across the field three, four miles an hour and expect it to work, because to the degree you get coverage is to the degree you will get killed, period.”

He quoted the late Madera County Farm Advisor George Levitt: “If you don’t get good coverage, you’re not going to get control. Speed does not kill. Slow down, do it right the first time and you won’t have to go back and try to play catch‑up later on.”

Burkdoll expects moderate to heavy mite pressure in tree fruit, almonds and vineyards in 2025 and stressed the value of biological controls in IPM. “An integrated approach to spider mites is always recommended, and involved in that approach will be the use of beneficial insects, particularly fostering six spotted thrips populations.”

He cautioned against overuse of broad-spectrum insecticides like pyrethroids and organophosphates, saying they harm both pests and beneficial species. “They kill most arthropods, spiders, predatory mites, six spotted thrips… If you can back off on those or wait till the last minute or use something else that isn’t as broad-spectrum or a more targeted approach, that’s always an advantage in the long term.”

For dormant-season mite management, Burkdoll noted selective use of pyrethroids, especially when mixing up chemistries, to avoid resistance. “Going out there broad-spectrum with pyrethroids early season is putting you on a treadmill for other pests. You’re going to have to spray again and again. So using IPM, mixing up chemistries, using different modes of action, and they have to work; you have to have something that works.”

He recommends following UC guidelines for mite management rooted in decades of research. “Older chemistries that have been around, they’ve been thoroughly tested, gives you a pretty good ballpark of what you can use. Just mix up the modes of action. Don’t use the same group number.”

Listen to the full conversation with Burkdoll on the MyAgLife Daily News Report.

2025 Crop Consultant Conference: Earn CEUs and Explore the Latest in Ag This September

By
Taylor Chalstrom
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The 2025 Crop Consultant Conference returns September 24-25 at the Visalia Convention Center, bringing together California’s leading PCAs, CCAs, researchers and industry professionals for two days of learning, networking and innovation in the heart of Central Valley agriculture.

Hosted by Progressive Crop Consultant, MyAgLife and Western Region Certified Crop Advisers, the Crop Consultant Conference is California’s premier event for crop consultants committed to advancing sustainable, profitable farming. Attendees can look forward to a packed agenda that includes expert-led sessions, CEU opportunities, novel research and practical field-ready strategies designed to meet today’s challenges head-on.

Comprehensive, Flexible CEU Opportunities
One of the conference’s greatest strengths is its dual-format CEU education program. Attendees can earn continuing education units (CEUs) for CA DPR, CCA, FREP, NDA and AZDA through both in-person and online sessions, providing the flexibility busy ag professionals need.

Beginning April 1, 2025, a new expert-led online session launches on the first of each month, covering topics like tree nut economics, advanced irrigation management and more. In-person sessions during the conference will offer extensive CE credit opportunities, with online access to additional courses extended through Dec. 31, 2025.

“This flexibility allows PCAs and CCAs to balance their work schedules while advancing their knowledge and skills,” said Jason Scott, CEO of JCS Marketing, Inc. “And with registration priced at just $345, it’s an incredible value, translating to pennies per CE credit.”

Practical Knowledge and Cutting-Edge Innovation
This year’s program emphasizes practical, immediately actionable insights. Topics will include soil health, pest and disease management, regulatory updates, climate-smart farming practices and the latest advancements in ag technology.

“This strategic location in Visalia allows participants to connect directly with innovations shaping the future of crop consulting,” Scott said.

Attendees will have full access to the conference trade show, showcasing the newest products, services and technologies in agriculture. It’s a rare opportunity to see the tools that can enhance consulting practices and client results firsthand.

A Full Conference Experience
Beyond earning CEUs, participants will enjoy breakfast and lunch both days, a lively networking mixer and ample opportunities to build connections with industry leaders, decision-makers and peers.

“This event is more than just lectures; it’s a platform for collaboration, innovation and professional growth,” Scott said. “It’s where future-forward crop consulting happens.”

High Demand: Register Now
Given the conference’s comprehensive educational offerings, affordable pricing and outstanding networking opportunities, both registrations and sponsorships are expected to sell out quickly.

“This is your chance to be part of a transformative experience that will elevate your professional knowledge and expand your industry network,” Scott said.

Secure your spot today and join us in Visalia this September for the 2025 Crop Consultant Conference.

Register now at myaglife.com/ccc

Effect of Almond Shell Mulch Application on Established Alfalfa Fields

By
Sarah Light | UCCE Agronomy Farm Advisor, Sutter, Yuba and Colusa Counties, Rachael Long | UCCE Field Crops and Pest Management Farm Advisor Emeritus, Capitol Corridor and Taiyu Guan | UCCE Assistant Specialist, Sutter-Yuba Counties
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Almond shells are lightweight but bulky, making them difficult and costly to spread due to the high volume needed per acre. Given limited impacts on soil fertility and yield, this practice is most practical for alfalfa fields located close to almond shell sources (all photos courtesy S. Light.)

Almond shells were applied as a mulch to an established alfalfa field in Yolo County over a two-year period. The intent of the study was to see if alfalfa could serve as a sink for almond shell byproducts after processing without affecting stand productivity. Alfalfa is deep-rooted and fixes nitrogen, which may allow for application of high-carbon materials like almond shell mulches.

The first year, almond shells were applied in October 2021 to a three-year-old stand at 4 to 8 tons per acre. By spring 2022, the almond shells had mostly decomposed. Almond shells were applied to the same test plots in November 2022 at 12.5 tons per acre. Additional field treatments included gypsum at 2 tons per acre per year and an untreated control. In addition to yield, test plots were evaluated for stand vigor, percent cover (bare soil, alfalfa, weeds) and weed pressure. Soil fertility and soil health measurements were also collected during this trial, including aggregate stability, compaction, soil moisture and soil cracking.

Outcomes of Mulch Application on Crop and Soil Metrics
The almond shell mulch did not reduce stand vigor as measured by the number of alfalfa plants per square foot. Alfalfa yields were likewise not significantly reduced (P>0.05), though they trended lower in almond shell plots for the first spring cutting (Fig. 1 and 3) and then evened out and were slightly higher than control plots in late summer for both years of this study (Fig. 2 and 4). Almond shells are high in C and low in N. Amendments with a high C:N ratio can tie up N as they break down. The slight reduction in spring yields might be due to initial spring tie-up of N for feeder roots from the almond shell application.

Figures 1-4. Alfalfa yields were not significantly different between the almond shell and control treatments (P>0.05), though trended slightly lower in the spring harvest followed by increased yields in midsummer where almond shells were applied to established alfalfa stands the previous fall in both 2022 and 2023. Gypsum likewise showed trends for higher alfalfa yields, indicating benefits to soil health at our study site with relatively high clay soils.

For soil health metrics, almond shell applications showed benefits of reduced soil cracking (Fig. 5) and soil compaction in the top three inches of soil (Fig. 6). Soil cracking is common in clay soils and can tear feeder roots apart in perennial crops like alfalfa. Soil compaction, a common problem in alfalfa due to equipment traffic during multiple harvests, can lead to yield and stand loss, poor water infiltration and reduced microbial activity. Our study shows almond shells provide an opportunity to mitigate surface soil compaction once the alfalfa has established. There were no changes to other soil health metrics like aggregate stability and bulk density after two years of this trial, nor did the almond shell mulch suppress weeds at rates applied.

Figure 5. One measure of soil health is the degree of cracking as soils dry. Applications of almond shell as a mulch to alfalfa growing on a relatively high clay soil significantly reduced levels of cracking.
Figure 6. Soil compaction is measured using a penetrometer, which collects pressure (pounds per square inch (PSI)). Less pressure was needed to penetrate soil in the top 3 inches in plots that had almond shells applied as a mulch (not incorporated).

Apart from electrical conductivity (EC), which measures salinity levels in soil, soil measurements were not significantly different by treatment. Gypsum is a highly soluble salt, and EC was higher in the gypsum plots compared to the almond shell and control plots. Even though differences were not statistically significant, there were some interesting trends in soil measurements. Specifically, almond shells have about 30 pounds of potassium per ton (36 lb K₂O/ton), which can eventually leach into the root zone with rain or irrigation as almond shells decompose. In this project, there was more potassium in soils with almond shell mulch compared to gypsum or control plots. In addition, plots with almond shells had more total carbon and total organic matter. Soil samples were collected in the top foot of soil and shells were applied to the soil surface. It is likely the soil sampling depth affected our ability to measure differences in soil K and C. Other measurements like cation exchange capacity, magnesium, calcium and total N were not different by treatment.

Soil water measurements were collected in this trial. Infiltration measurements were taken for the first four inches of water applied. Infiltration measures the rate at which water moves into the soil. Infiltration was fastest in plots with almond shells for all 4 inches of water. However, the differences were only statistically significant for the 4th inch of water (Fig. 7). In a heavy rain event, rapidly moving water into the soil is advantageous for preventing runoff and retaining water in the fields. Saturated hydraulic conductivity measures the rate that water flows through saturated soil. Though not statistically significant, almond shell plots also had a faster saturated hydraulic conductivity (faster water flow rate) compared to other treatments.

Figure 7. Water infiltration was measured for the first 4 inches of water. This simulates how long it takes water to move into the soil during a heavy rain event. The almond shell plots had the fastest water infiltration (fewest minutes required per inch) for all measurements. The 4th inch of water is shown.

Volumetric water content was measured in the top 6 inches of soil. The total differences in soil water content at any point in the season were negligible for on-farm irrigation decisions. However, some interesting trends were observed. In rainy months, almond shell plots had higher water content after rain events, likely because of increased infiltration and hydraulic conductivity. However, in the summer months, almond shell plots had slightly less water in the top 6 inches of soil. These are the months when the yields trended slightly higher in the almond shell plots. Alfalfa is a crop that yields relative to water applied; this reduction in water content is likely due to the increased alfalfa yield in plots with almond shell application.

Cost Considerations and Logistical Factors of Shell Application
Almond shells are both bulky and very lightweight, making them challenging to spread compared to other amendments. However, shells are a dry material, and transportation costs are not lost to water weight as with other soil amendments like compost. Good soil coverage requires a high volume of shells per acre, and multiple truckloads per field will be needed. This increases hauling and spreading costs. For the Sacramento Valley where this field trial was conducted, freight costs are $10 per ton within 50 miles and spreading costs are $15 per ton. These costs are high given the lack of measurable differences to soil fertility and yield. Thus, this practice is best suited for established alfalfa fields located near a source of almond shells to reduce freight costs.
Mulching is considered a soil conservation practice under both federal and state guidelines. However, mulch must be applied to a 2-inch depth and at a rate to achieve 70% soil coverage. At the highest application rate in our study (12.5 tons/acre), the depth of the mulch was under 1 inch.

Almond shell mulch rests on the soil surface of an alfalfa field. Researchers observed benefits such as reduced soil cracking and improved water infiltration without significant changes in soil fertility or productivity.

Key Takeaways
In our study, almond shell mulch in an established alfalfa field showed benefits of reduced soil cracking, reduced soil compaction and increased water infiltration without negatively affecting overall stand health and yields at the rates of almond shells applied. Alfalfa has deep roots and fixes N, making it a resilient crop for diverting high-C almond shell waste byproducts from nearby orchards to alfalfa stands, improving organic matter recycling in the region. Since almond shells are not incorporated, any N tie-up would be slow and only in the soil surface. Incorporating almond shells to alfalfa stands prior to planting or applying shells to first-year stands is not recommended due to issues with tying up N with a high C:N product that could affect stand establishment and plant growth. This project was an initial evaluation and did not quantify the optimum application rate to alfalfa fields.

Funding was provided by the California Alfalfa and Forage Research Foundation. Thank you to our grower collaborator for supporting this work.

The original version of this article first appeared in the April/May 2025 issue of Hay & Forage Grower.

UC Works with Blackeye Growers to Improve Varieties for the California Industry

By
Nick Clark | UCCE Agronomy and Nutrient Management Farm Advisor, Kings, Tulare and Fresno Counties, Michelle Leinfelder-Miles, Sarah Light | UCCE Agronomy Farm Advisor, Sutter, Yuba and Colusa Counties and Bao-Lam Huynh | Assistant Professor of Nematology, Dept. of Nematology, UC Riverside Assistant Professor of Nematology
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Figure 3. Recently released CB77 has a slightly larger, whiter seed compared to CB46. More lygus stings are visible in CB46 (photo courtesy B. Huynh.)

Black-eyed peas, also called cowpeas, are a bean species native to Africa in the Vigna genus of legumes. Cowpeas were introduced to the United States as early as the 16th century by Spanish colonists and through the trans-Atlantic slave trade. “Blackeyes,” as they’re called locally, are grown by California growers on approximately 8,000 acres each year to produce a nutrient-rich food for consumers. Most production in California goes to the dry bean sector for canning and bagging. A small amount of the crop is produced for fresh consumption, similar to green beans or snap peas, and may be sold at farmers markets.

Blackeyes are an important crop in the San Joaquin and Sacramento valleys, where diverse crop rotations are common. A relatively drought-tolerant crop, blackeyes are usually flood or furrow irrigated. Growers rarely fertilize with nitrogen since blackeyes efficiently fix nitrogen from the air due to the plant’s symbiotic relationship with a root-inhabiting Rhizobia bacteria species. Additionally, blackeyes are moderately tolerant of salinity and can grow in conditions where yield declines would be expected for other summer annuals like corn and tomatoes. These characteristics of blackeyes can be an economic incentive to grow them in some years and will be important in California, particularly under hotter and drier conditions expected with climate change.

Plant Breeding for the Future
As California shifts toward drier and more extreme weather, blackeyes, like most cultivated plants, will experience new pressures that growers will be first to manage. Heat stress and drought vulnerability, emerging and invasive insect pests, increased weed competition and the evolution of endemic and invasive diseases are some of these pressures. Plant breeding that considers these stresses will help the industry stay ahead of the curve.

UC has a long history of variety development for the California blackeye and garbanzo industries. For blackeyes, the current standard varieties are CB46 and CB50, which were released in 1990 and 2009, respectively. CB46 is high-yielding and has Fusarium wilt race 3 resistance, but it is susceptible to virulent and aggressive races of root-knot nematodes, Fusarium wilt race 4, aphids, lygus and late-season diseases known collectively as ‘early cut-out.’ Additionally, the market now prefers larger seed and whiter grain than what CB46 provides. CB50 is high-yielding, has larger seed size than CB46 and is resistant to Fusarium wilt races 3 and 4 and root-knot nematodes.

To support plant breeding efforts, new breeding lines and cultivars are trialed at research facilities and then on commercial farms to evaluate material across environmental conditions. New materials are evaluated against commercial standards for yield, quality and pest resistance. The cultivars and advanced lines that have been trialed across regions and years are described in Table 1. UCCE farm advisors have collaborated for more than 10 years with UC Riverside plant breeders to test improved lines and, over the last five years, have conducted 21 trials across seven locations in the Central Valley.

Table 1. Descriptions of California blackeye cultivars and new breeding lines.

The variability in precipitation and average air temperature down the Central Valley can influence blackeye phenotypic traits. For example, in Five Points (southern San Joaquin Valley) from 2020 to 2025, the mean annual precipitation was 7.6 inches, whereas Davis (southern Sacramento Valley) had a mean annual precipitation of 17.1 inches. Similarly, average daily air temperature in June, July, August and September over the same five-year period in Five Points was 78 degrees F but was 73 degrees F in Davis. It is important to test experimental lines across regions to understand how they will perform in different environments.

California growers who serve on the California Dry Bean Advisory Board have identified high yield, seed quality and disease resistance as top priorities for plant breeding efforts. They have also emphasized the importance of regional acclimation. The following are some highlights from research funded by the California Dry Bean Advisory Board, USAID Feed the Future Innovation Lab for Legume Systems Research and California Crop Improvement Association, made possible through the generous support of numerous growers, bean harvesters and bean handlers.

Regional Trial Results
Yield results from 2020 to 2024 trials are summarized for the Sacramento and San Joaquin valleys (Table 2), where average yields ranged from 1,091 to 3,582 pounds per acre. The lowest yield occurred in 2020 and the highest in 2024, both in the Sacramento Valley. Interestingly, yields in the San Joaquin Valley were 27% lower than in the Sacramento Valley in 2024. While yields are usually higher in the San Joaquin Valley, the lower yields may have resulted from a prolonged heat wave and above-average nighttime temperatures, which caused significant crop losses.

Table 2. Annual blackeye bean cultivar and advanced breeding line yield (lb/ac) in the Sacramento and San Joaquin valleys.

Seed size is an important quality factor in blackeye production related to consumer preferences. Average seed size, reported as the weight of 100 seeds, for the last five years of trials is shown in Table 3. Seed size ranged from 20.0 grams per 100 seeds for CB77 (2020, Sacramento Valley) to 27.8 grams for CB50 (2024, Sacramento Valley). CB5 and CB50 consistently have the largest seed size across sites from year to year, while the experimental lines tend to have smaller seed size, similar to CB46 and CB77. Over the last five years, average seed size in the San Joaquin Valley was approximately 7% smaller than in the Sacramento Valley.

Table 3. Annual blackeye bean cultivar and advanced breeding line seed size (100 seed weight in grams) in the Sacramento and San Joaquin valleys.

An important insect pest of blackeyes is lygus, which kills fruits before they develop, resulting in direct yield loss. Lygus feeding, called “stings,” also damages and discolors seeds after pods develop (Fig. 1), which reduces yield and diminishes the quality of the beans. The results for lygus damage, shown as the percent of seed with lygus stings, are shown in Table 4. The average lygus damage ranged from 2% for CB77 (2020, Sacramento Valley) to 43% for CB5 (2021, Sacramento Valley). Average lygus damage in the Sacramento Valley over the last five years was 20%, while in the San Joaquin Valley it was 7%. Importantly, under the heavy lygus pressure in the Sacramento Valley, the five-year average lygus damage was lower for experimental line 07KN-74 and newly released CB77 compared to the commercial cultivars CB5 and CB46. This demonstrates a high yield potential and reduced need for insecticides to control lygus with the newer material. With little development of new insecticides for use in dry beans, the importance of insect-resistant varieties cannot be overstated.

Figure 1. Lygus susceptible (left) and lygus tolerant cowpea (right) (photo courtesy Rachael Long, UCCE.)
Table 4. Annual blackeye bean cultivar and advanced breeding line lygus damage (% of seed damaged) in the Sacramento and San Joaquin valleys.

New material is also evaluated for disease resistance (data not shown). The evolution of Fusarium wilt provides an example of why plant breeding is critical to disease management. CB5 is an older blackeye variety that is susceptible to Fusarium wilt race 3. CB46 was released as a commercial variety with Fusarium wilt race 3 resistance. However, after years of production, CB46 started showing susceptibility to Fusarium wilt race 4. CB50 was then introduced as a new variety with resistance to both Fusarium wilt race 3 and race 4. During trialing, advanced breeding lines are grown alongside traditional cultivars (like CB5, CB46 and CB50) to quantify how new material compares to varieties already on the market. Lines are evaluated over multiple years to capture variability in pest pressure, weather and other yield-limiting conditions.

Research Outcomes
Recently developed varieties show resistance to disease and aphids, while new breeding lines show great promise for nematode or lygus resistance. Recently, CB77 was publicly released as an improved variety with similar yield and quality to CB46 but with resistance to cowpea aphid (Fig. 2). It also has a brighter white color than CB46 (Fig. 3). The California Crop Improvement Association currently holds foundation seed of CB77 and will distribute it to growers who successfully apply to grow certified seed for commercial production.

Figure 2. CB77 with resistance to cowpea aphid (left) and CB46, which is susceptible to cowpea aphid (right) (photos courtesy Rachael Long, UCCE.)

Lines N2 and 07KN-74 will be ready for public release within a year. Line N2 is a root-knot nematode-resistant line with high yields in the San Joaquin Valley. Root-knot nematodes damage roots, which diminishes water uptake and yield. As fumigants are phased out through regulatory processes, host resistance and alternative strategies for reducing root-knot nematode damage must be taken into consideration. Line 07KN-74 is a lygus-tolerant variety with moderate yield, similar to or slightly lower than the commercial standard CB46. This article summarizes the plant breeding and trialing efforts to improve blackeyes for the California industry. Yield, quality and pest resistance are important traits for plant breeding efforts, and this article summarizes years of data across multiple locations in the Central Valley. These evaluations are ongoing and provide growers with first-hand information on how new genetic material performs under commercial farming conditions. Growers who are interested in learning more or hosting on-farm trials should contact the authors, who would be glad to help make those arrangements.

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