Two weeks ago at the Cotton Beltwide Conferences in San Antonio, I shared results from our Arizona organic cotton IPM work—and the response was immediate. Questions, follow-ups, and hallway conversations kept circling back to the same point: Arizona is different.

Arizona produces the highest-yielding cotton in the U.S. while using the lowest amount of insecticides in the Cotton Belt, the result of more than 35 years of coordinated, area-wide IPM. That same system could keep Lygus pressure low enough for organic cotton to be successful—but only if management decisions reflect organic realities.

In vegetable-focused regions like Yuma, cotton is treated as a rotational crop rather than a primary cash crop. Winter vegetables drive regional profitability and account for a significant share of Arizona’s certified organic acreage. Even so, Yuma still represented roughly 10% of the state’s cotton acreage last year, producing about 10,000 acres out of approximately 100,000 acres statewide. Cotton fits strategically as a summer rotation that benefits from the landscape-level pest suppression already in place.

Over the last 35 years, Arizona cotton IPM has evolved from an average of 11 insecticide sprays per season to fewer than two statewide, driven by decades of disciplined decision-making by growers and PCAs using selective insecticides, transgenic technologies, and conservation biological control.

Since 1996, those IPM-first choices have saved more than $700 million and prevented over 40 million pounds of insecticide active ingredient from being applied, creating the area-wide pest suppression that defines Arizona cotton today.

That foundation is what makes organic cotton feasible in this region: our field data showed limited benefit from certain OMRI-listed insecticides for Lygus, reinforcing a message shared at Beltwide that, in Arizona organic cotton, the smartest spray may be no spray at all.

Not all sunshine and cotton bolls. Important challenges remain in Arizona organic cotton IPM, and we’ll be sharing more details soon.

This work was funded in part by Western IPM Center, which also featured the project—read the story HERE.

Figure 1. The Arizona cotton IPM continuum illustrating how shifts in IPM tools and practices reduced statewide insecticide use over the past 35 years.

Click HERE to read more about our Arizona Cotton IPM Story.

Regenerative agriculture (RA) crop production systems have recently been popularized in many agricultural communities. Claims are often made that RA systems are better than conventional agriculture (CA) crop production systems, which are commonly considered to be input intensive.

The definition of an RA system is highly dependent on the practitioner, and many definitions can be found. In general, RA is a principles-based approach that aims to restore and enhance soil health, biodiversity, and ecosystem services through practices such as reduced tillage, cover cropping, diverse rotations (including fallow or resting periods), crop residue retention. In some cases, it includes agroforestry and/or the integration of livestock.

Proponents of RA argue that it can increase soil organic carbon (SOC), which is a proxy measurement related to stable soil organic matter (SOM). They also contend that RA practices improve soil water-holding capacity and soil systems resilience (which is an extremely broad category).

Regenerative agriculture systems have the basic objective of increasing on-farm biodiversity and delivering long-term improvement in productivity and soil health as compared to conventional crop production systems.

Recent reviews of the literature have addressed the overall trends in field research associated with RA systems in comparison to CA crop production systems. Some studies have demonstrated some positive effects of RA systems on soil condition and soil health.

Research reviews clearly illustrate that the context of the studies is very important in interpretation and there is clear evidence of major gaps in describing and quantifying effects from RA systems (Montgomery and Biklé, 2021 and Khangura, et al., 2023).

BLUF (Bottom Line Up Front) Statement:
Regenerative systems promote crop and soil management practices that have been recognized and utilized for many years, hundreds of years in fact. Current research comparing RA and CA systems are highly variable. All asserted benefits of RA systems are highly dependent on climate conditions and the CA systems used for comparison.

Overall, RA practices generally contribute positively to soil health. However, there is no definitive evidence of RA systems being superior to CA crop production systems.

Pros – Objectives of RA systems:

• Soil carbon and structure. A meta-analysis of temperate systems found that reduced tillage and inclusion of grass-based rotation and resting/fallow periods could increased SOC relative to CA. Studies in cooler and humid climates show that RA practices can build SOC stocks over several decades (Jordan, et al., 2022). This does not transfer to other agroecosystems in drier and warmer environments.
• Soil health and resilience. Practices that increase incorporation into soil crop residues (organic material), crops with different types of root systems, and crop rotations that include legume crops can improve soil aggregate stability, infiltration, internal soil drainage, and retention has been found in some studies and reviews (Khangura, et al., 2023).
• Biodiversity and ecosystem services. Diversified crop rotations, the use of cover crops, and crop–livestock integration can increase soil biodiversity. It is also contended that crop pollination and pest-regulation (insects, weeds, and diseases) can be improved with RA systems versus CA. However, these effects are commonly poorly quantified in most studies (Sher, et al., 2024). Thus, some of these benefits are quite speculative.
• Co-benefits and livelihoods. There are some publications that conclude that RA systems can be more profitable or financially resilient for farmers. But from these studies it is only possible for RA superiority to CA systems when there are price premiums, reduced input costs, or ecosystem payment schemes that are available. Highly variable yields, the need for policy support and payment mechanisms are commonly needed to make RA systems viable at scale (Reuters, 2024).

Cons / limitations compared to conventional cropping systems:

• Yield uncertainty and trade-offs. In most studies, RA practices do not consistently or significantly change crop yields relative to CA systems, particularly in short-term studies, anything less than a decade. Overall, review of the literature shows no consistent or general “win-win” RA situation that will reliably increase yields while increasing SOC. Yield responses are highly variable by crop, region, and the time elapsed since RA systems were adopted. In many cases, the transition years into RA systems cause yield reductions. The site-specific constraints can be quite variable it is difficult to identify consistent positive trends in RA system benefits over CA systems (Jordan, et al., 2022).
• Greenhouse gas and livestock trade-offs. RA systems that integrate livestock or increasing manure inputs can boost SOC and encourage soil biodiversity. These

types of RA systems have been shown to raise methane and nitrous oxide emissions. As a result, any net climate benefits are dependent on whole-system greenhouse-gas accounting, which is often not done or effectively included in most RA studies (Sher, et al., 2024).

• Evidence gaps and heterogeneity. Most of the cases found in the current literature on RA systems evaluation address single practices such as no-till versus conventional tillage, the use of cover crops, and animal manure application regimes. There is a substantial absence of long-term, fully integrated RA/CA systems comparisons. Accordingly, the results found in the current literature are highly variable and context dependent (soil type, climate, access to RA-friendly market benefits, etc.). As a result, generalization is extremely limited in comparing RA and CA systems (Jordan, et al., 2022).
• Adoption barriers. Moving to RA systems often requires new knowledge, increased and different levels of labor reallocation, equipment changes, and often many upfront investments to access unique markets and secure technical support. Incentive structures (i.e., subsidies) are commonly needed to make RA system transitions from CA systems and without that, adoption can be slow and highly variable (Reuters, 2024).

Regenerative systems promote crop and soil management practices that have been recognized and utilized for many years, hundreds of years in fact. Current research comparing RA and CA systems are highly variable. All asserted benefits of RA systems are highly dependent on climate conditions and the CA systems used for comparison.

There is a definite need for long-term, system-level experiments. The appropriate measurement and quantification of RA and CA system management comparisons and soil health parameters are essential priorities to help resolve the many remaining uncertainties associated with RA systems (Jordan, et al., 2022).

Overall, RA practices can potentially improve soil health. However, there is no definitive evidence of RA systems being superior to CA crop production systems.

References:
Jordon, M. W., K. J. Willis, P. C. Bürkner, N. R. Haddaway, P. Smith, & G. Petrokofsky. 2022. Temperate regenerative agriculture practices increase soil carbon but not crop yield — a meta-analysis. Environmental Research Letters 17(9):093001. doi:10.1088/1748-9326/ac8609.  

Khangura, R., D. Ferris, C. Wagg, & J. Bowyer. 2023. Regenerative agriculture—A literature review on the practices and mechanisms used to improve soil health. Sustainability 15(3):2338. doi:10.3390/su15032338.  

Montgomery, D. R., & A. Biklé. 2021. Soil health and nutrient density: Beyond organic vs. conventional farming. Frontiers in Sustainable Food Systems 5:699147. doi:10.3389/fsufs.2021.699147.  

Sher, A., H. Li, A. Ullah, Y. Hamid, B. Nasir, & J. Zhang. 2024. Importance of regenerative agriculture: Climate, soil health, biodiversity and its socioecological impact. Discover Sustainability 5:462. doi:10.1007/s43621-024-00662-z.  

Reuters. 2024. Rewarding farmers for regenerative agriculture is 'critical for decarbonising the food sector'. Reuters, June 10, 2024. (news article).  

Guardian (news). 2024. Cows help farms capture more carbon in soil, study shows. The Guardian, Sept. 28, 2024. (news article).  

Click here and hit ‘download’ for a PDF version of this article. 

Cladosporium leaf spot on spinach has been coming into the Yuma Plant Health Clinic in increasing numbers as of late.

Most samples have been brought in displaying early lesions which start on the upper leaf surface (adaxial side). The lesions form a sunken cavity visible under a hand lens. As the spot progresses, chlorosis can be observed on the lower leaf surface (abaxial side) corresponding to the lesions above. With disease progression, lesions on both leaf surfaces become necrotic, papery, and tan, with little to no surrounding yellowing or haloing. Early lesions are usually tan to white or yellowish and measure less than 3 mm in diameter. Under favorable environmental conditions and high leaf moisture, individual spots may coalesce into larger, irregular blotches that form dark green fuzzy growth as the fungus begins to sporulate.

Cladosporium leaf spot is caused by the fungal pathogen Cladosporium variabile and possibly other closely related Cladosporium species which have shown pathogenicity in lab assays. Disease development is favored by the high humidity and extended periods of leaf wetness Yuma has been experiencing. The pathogen can be seedborne, making the use of clean or disinfested seed especially important. However, spread between fields via wind and water is also likely contributing to the current outbreak of this disease.

Research has shown that QoI fungicides (FRAC Group 11), also referred to as the strobilurins, can be effective in managing this disease when applied preventively (Higgins 2020). However, in Arizona, these products are not labeled for control of Cladosporium leaf spot on spinach. While this year may represent an outlier associated with our atypical winter weather, repeated outbreaks in future seasons would suggest the need to re-evaluate long-term management strategies should this disease become a recurring issue. Please continue to evaluate the economic impact this disease is having on your spinach production, as documentation of yield loss, quality reductions, and increased management costs will be critical in determining the need for research support and potential registration of additional management tools.

If you have any concerns regarding the health of your plants/crops please consider submitting samples to the Yuma Plant Health Clinic for diagnostic service or booking a field visit with me:

Chris Detranaltes, Ph.D.
Cooperative Extension – Yuma County
Email: cdetranaltes@arizona.edu
Cell: 602-689-7328
6425 W 8th St Yuma, Arizona 85364 – Room 109

It is with mixed emotions that I write to inform you that this will be my last University of Arizona Vegetable IPM Update. The reason – I am retiring. Thank you for your support over the years. It’s been an honor and a privilege working with you and serving this ag community.

Figure 1. Automated Thinning & Weeding Technologies Field Day.
(Photo credits: Rosa Bevington)

An Economic Reality Check for Small-Scale Arizona Lettuce Producers

As precision robotic weeding and thinning technologies become more accessible, Arizona's small-scale lettuce growers increasingly ask: Does the investment in robotic systems make economic sense for my operation? With labor challenges intensifying across the state and wage pressures mounting, our recently completed trial provides a timely economic analysis specific to Arizona's growing conditions and regional labor markets.

The Economics of Labor vs. Technology in Arizona

Traditional lettuce hand weeding and thinning costs in Arizona:

• Labor represents one of the largest operational expenses in Arizona lettuce production
• Arizona minimum wage continues to rise, now exceeding $16 per hour in many regions
• Seasonal worker availability has become increasingly unpredictable, with competition from other industries and reduced cross-border workforce mobility
• In Arizona's major growing regions like Yuma, manual hand thinning and weeding costs range from $100 to $454 per acre, depending on field conditions, weed density, and bed width
• Inexperienced crews may cause crop damage, reducing marketable yield and compounding labor costs
• Hand operations require supervisory oversight to maintain quality standards

Precision robotic weeding/thinning system costs:

• Outright purchase: $250,000–$1.2 million+, depending on system sophistication
• Rental/lease options: $5,000–$15,000 per season (varying by availability in Arizona and neighboring states)
• Service-based models (Robotics-as-a-Service): $166–$304 per acre
• Monthly lease: ~$25,000 per month for large operations
• Operating costs: Fuel, maintenance, software updates, and technical support
• Learning curve: Training and implementation time

Key Economic Factors to Consider for Arizona Operations

Farm Size Threshold
In Arizona, robotic systems become economically viable for farms where weeding and thinning labor costs exceed $8,000–$12,000 per season. Small operations (under 20 acres of lettuce) may find rental or shared-equipment arrangements more cost-effective than outright purchase. Service-based models (RaaS) have emerged as a practical entry point, particularly for farms in Yuma County and other Arizona production regions where labor scarcity is acute.

Labor Availability Crisis in Arizona
Arizona's desert lettuce production regions face acute labor constraints. In regions where reliable labor is scarce or increasingly expensive, a reality across Arizona's major growing areas, precision robotic systems provide operational predictability while reducing damage risk. One precision robotic system operating consistently may replace 3–5 seasonal hand workers, improving both economics and quality control. Arizona growers who have struggled with labor availability during critical thinning and weeding windows recognize the operational value of robotic consistency.

Marketable Yield
Arizona's intensive production system and specialized lettuce varieties demand precision crop management. Many Arizona growers report hand labor costs ranging from $161 to $454 per acre, depending on specific field conditions, weed density, and bed width. Even modest yield improvements of 5% from reduced crop damage can offset system costs, particularly when inexperienced hand crews are the alternative. Given Arizona's premium lettuce market positioning, yield quality and consistency provide additional value beyond simple volume.

Operational Flexibility and Regional Equipment Availability
Renting or leasing robotic weeding/thinning systems allows Arizona small farms to avoid large capital expenditures while testing technology fit. Equipment providers now offer season-specific rental arrangements suitable for small-scale Arizona operations. Robotics-as-a-Service (RaaS) models, where growers pay per acre or per hour rather than owning hardware, have emerged as a game-changer for Arizona small operations, with several providers now establishing regional service capabilities in Yuma and surrounding areas.

Financial Decision Framework for Arizona Growers
Consider purchasing/owning robotic weeding/thinning systems if:

• Your operation has 30+ acres of lettuce requiring annual weeding and thinning
• You can achieve 80+ operational hours per season to justify equipment investment
• Local labor costs exceed $18–$22 per hour (now the reality across much of Arizona)
• You prioritize operational consistency and yield protection over capital flexibility
• You have 200+ acres and can achieve a 2–3 year ROI

Consider service-based (RaaS) or rental/leasing robotic systems if:

• Your operation has 10–30 acres of lettuce
• You want to test technology fit before major capital investment
• Labor availability is seasonal and unpredictable (increasingly common in Arizona)
• You prefer to minimize equipment ownership and maintenance responsibilities
• You want to access the latest technology without capital expenditure
• You want to pilot robotic systems during your most labor-intensive seasons

Stick with traditional hand operations if:

• Your farm is under 10 acres of lettuce requiring intensive management
• Local labor is readily available at competitive rates (increasingly rare in Arizona)
• You have experienced, retained crews who consistently perform high-quality work
• Your capital budget is constrained

Return on Investment (ROI) for Arizona Operations

The primary driver for adoption is the economic disparity between robotic costs and manual labor, a gap that has widened significantly in Arizona.

Labor Cost Baseline for Arizona: In Arizona's major growing regions like Yuma, manual hand thinning and weeding costs range from $100 to $454 per acre, with an average of $250–$350 per acre for experienced crews during peak seasons.

Payback Period: Most robotic systems aim for a break-even point within 2–3 years. For Arizona operations relying on expensive seasonal labor or facing acute worker shortages, ROI can sometimes be achieved within a single season, particularly if labor costs exceed $300 per acre.

Secondary Benefits: Beyond labor savings, precision robotic systems can increase yields by approximately 5% through reduced crop damage compared to manual crews and better weed control. For Arizona's premium lettuce market, quality improvements and consistency may provide additional market premiums.

Arizona-Specific Considerations:

• Desert soil conditions and shallow-rooted lettuce make mechanical damage from conventional cultivation particularly costly
• Water efficiency gains from precision robotic systems align with Arizona's water sustainability priorities
• Extended growing season in southern Arizona may allow higher utilization rates, improving equipment ROI

Key Takeaway for Arizona Growers

Precision robotic weeding and thinning technology is no longer exclusively for large-scale operations. For Arizona's small-scale lettuce growers facing mounting labor costs, unpredictable seasonal workforce availability, and premium market positioning, the economics increasingly favor at least exploring service-based, rental, or shared-equipment options. Arizona's unique labor market dynamics and growing season characteristics make robotic technology particularly relevant. The decision hinges on your specific operation: farm size, local labor costs, available capital, and risk tolerance for new technology.

Interested in Field Trials?
If you have any questions or are interested in doing a trial, please reach out to weed specialist Mazin Saber at the University of Arizona Yuma County Cooperative Extension. Dr. Saber leads research initiatives comparing manual labor to commercially available robotic weeding technologies to establish sustainable weed control programs for Arizona desert agriculture.

Bagrada bug (Bagrada hilaris) is an invasive stink bug recently established in the desert Southwest of the U.S. It has become a major economic pest of many cruciferous vegetable crops cultivated in fall and winter in the agricultural valleys of Arizona and southern California. Crop injury caused by Bagrada bug feeding has resulted in major economic losses. Depending on the crop species, Bagrada bugs may cause yield losses of 15-35%. Effective options for controlling Bagrada bug infestations in organic crops are limited, creating a significant challenge for organic growers. The objective of this study was to evaluate selective organic-approved insecticides to identify new tools that organic vegetable producers in the desert can use to manage Bagrada bugs effectively.

This fall growing season, we conducted a field trial to evaluate several organic-approved insecticides against the Bagrada bug in broccoli. The results of our trial show that M-Pede and a tank mix of M-Pede and Entrust can provide approximately a 60% reduction in Bagrada bugs relative to the untreated check. Captiva Prime and Neemix also resulted in a nearly 50% reduction in Bagrada bug numbers. Aza-Direct, Entrust alone, and Botanigard each resulted in about a 30% reduction in Bagrada bugs relative to the untreated check (Fig. 1). Our observations indicate that the insecticides evaluated are unlikely to provide quick knockdown. Tank mix of M-Pede and Entrust, Neemix, and Captiva Prime resulted in 39, 35, and 34% reduction in damage caused by Bagrada bug feeding. Entrust alone and M-Pede resulted in Bagrada bug feeding damage reductions approaching 25% (Fig. 2). Previous research trials conducted in Yuma also show that mixture of Entrust and M-Pede, Entrust alone, Aza-Direct, and Pyganic can fairly suppress the pest (Palumbo 2022).

Figure 1. Number of Bagrada bugs per 10 broccoli plants as affected by biological
insecticide applications, Fall 2025. All insecticide treatments included Nu-Film
P at 1 pt./ac.




Figure 2. Percentage of broccoli plants with damage caused by Bagrada bug
feeding, Fall 2025. All insecticide treatments included Nu-Film P at 1 pt./ac.

Additional Reading Material:
Palumbo, J.C. 2024. Bagrada Bug Management Tips - 2024. Veg IPM Newsletter, Vol. 15, No. 18 University of Arizona, Department of Entomology. http://hdl.handle.net/10150/676902

Keith, M., & Calvin, W. 2025. The Evolution of Bagrada Bug Management in Desert Cole Crops: The Legacy of John C. Palumbo (2010–2025). Veg IPM Newsletter, Vol. 16, No. 21. University of Arizona, Department of Entomology. http://hdl.handle.net/10150/678668

In Yuma Valley, precipitation is not the primary driver of crop water supply; irrigation is. Yet rainfall still matters because it can act like a biological “switch,” briefly reshaping field conditions in ways that influence weeds and plant disease. A single storm can alter soil surface moisture, stimulate germination, increase canopy humidity, and adjust access and irrigation timing. For Integrated Pest Management (IPM), these short windows often have outsized consequences compared with the annual total. Using annual precipitation totals from AZMET (Yuma Valley station), 1987–2025, the long-term trend is slightly upward, but the signal is extremely weak relative to the natural variability.

Figure 1 summarizes annual precipitation over time and includes a fitted linear trendline (the red line). The long-term mean annual precipitation is 2.63 inches (the yellow line), emphasizing how arid this production system is. The most recent year provides useful context: 2025 annual precipitation was 5.91 inches, which is substantially above the long-term mean (by 3.28 inches). That single year does not redefine the long-term trajectory by itself, but it illustrates the central message of the dataset: large departures from the mean can occur even when the multi-decadal trend is weak.

Figure 1. Annual total precipitation at the AZMET Yuma Valley station (1987–2025). Points/line represent annual totals; the horizontal reference indicates the long-term mean (2.63 in). The fitted linear regression trendline indicates a slight increasing tendency over the period.

The trendline equation shown on the figure is:  

• y = 0.0111x − 19.58
• R² = 0.0074

The slope (0.0111 inches per year) corresponds to roughly 0.11 inches per decade, which is small in magnitude. Meanwhile, R² = 0.0074 indicates the linear trend explains less than 1% of the year-to-year variability, meaning annual precipitation is dominated by irregular storm years and interannual fluctuations, not a strong flat wetting or drying signal.

Why this matters for IPM

For pest management, the most relevant feature of Yuma Valley precipitation is not the weak long-term slope but the timing and periodicity of rainfall and the biological responses it triggers:

• Rainfall pulses can rapidly activate weed germination in disturbed soils.
• Microclimate shifts and disease favorability. Even modest rainfall can elevate leaf wetness and near-canopy humidity, creating short infection windows for moisture sensitive pathogens (crop- and growth-stage dependent).
• Rain-driven changes in host availability and microclimate can influence insect survival, dispersal, and population growth. The post-rain window is often when scouting provides the highest informational value because conditions shift quickly.
• Rain seldom replaces irrigation in Yuma, but it can affect field access and irrigation timing, indirectly shaping canopy structure and pest habitat.

The key message from Figure 1 is straightforward: annual rainfall in Yuma Valley does not exhibit a strong long-term linear trend from 1987 to 2025, and any increase suggested by the trendline is minor relative to variability. Years like 2025 (5.91 inches) sit far above the long-term mean (2.63 inches), highlighting that single-year abnormalities can be operationally meaningful even when the multi-decadal trend is weak. 

VegIPM Update Vol. 17, Num. 2

Jan. 21, 2026

Results of pheromone and sticky trap catches below!!

Corn earworm:  Few CEW moths were found in traps over the last two weeks; about average for mid-January.

Beet armyworm: BAW were collected across all locations over the last two weeks; and activity slightly increased in most areas. Above average for mid-January.

Cabbage looper:  Cabbage looper moth activity remains at all locations and above average for mid-January.

Diamondback moth: Adult activity slightly decreased across most locations. About average for mid-January.  

Whitefly: Adult activity remains low across all locations, about average for this time of year.

Thrips: Thrips adult activity remains low across locations, about average for this time of year.

Aphids: Winged aphid numbers increased over the last two weeks; below average for mid-January.

Leafminers: Adult leafminer activity remained low over the last two weeks, about average for this time of season.