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:
Cons / limitations compared to conventional cropping systems:
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).
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).
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Galls observed on the stems of begonias submitted to the clinic
Recently, we received a submission of begonias to the Yuma Plant Health Clinic that immediately presented a diagnostic challenge. At first glance, the symptoms seemed to point toward a familiar set of suspects. The plants had developed severe swelling of the stems, symptoms characteristic of physiological oedema or bacterial Agrobacterium-associated crown gall. But, as is often the case in plant diagnostics, appearances can be deceiving.
The begonias had been grown indoors in high-humidity terrariums and planter boxes. The symptoms were not associated with a particular begonia variety, nor were they consistently expressed across all plantings or cuttings. When the plants were removed from their planting substrate, however, another clue emerged: additional small galls were scattered throughout the root systems of those plants also showing the stem swellings. That observation changed the diagnostic picture considerably.
Galls observed on the roots of begonias submitted to the clinic
Dissection of both the swollen stem tissue and the roots revealed an abundance of eggs, juveniles, mature female nematodes, and giant cells, a classic signature of root-knot nematode (RKN) infection. Root-knot nematodes belong to the genus Meloidogyne, a group of microscopic roundworms that are among the most important plant-parasitic nematodes worldwide. Their typical symptom is familiar to many resulting in the formation of characteristic galls on roots.
These galls are not simply a physical wound created by the nematodes. Rather, RKNs actively manipulate their host. During infection, the nematodes secrete salivary compounds that alter plant growth and development, effectively hijacking normal cellular processes and redirecting them toward the formation of specialized feeding structures known as giant cells.
These giant cells become a nutrient-rich feeding site for the developing and mature nematodes. In doing so, the nematode establishes a sustained drain on the plant's resources. As infection progresses, the resulting disruption to the root system can interfere with nutrient acquisition and water uptake. Aboveground, this typically translates into stunted growth, declining foliage, wilting, and, in severe infestations, plant death. With more than 3,000 plant species reported as hosts to different root-knot nematode species worldwide, including many field and vegetable crops, the annual impact of these pathogens is enormous. Much research has been done on RKN in various crops, and reports of stem swellings occurring naturally is almost non-existent.
Yet the begonia case raises an especially interesting question: Why did a pathogen best known for producing root galls appear to be responsible for such dramatic swelling in the stems? This is where the environment becomes an essential part of the diagnosis.
The symptom is not the pathogen. It is a reaction of the plant to the presence of a pathogen. One of the most important principles in plant pathological diagnostics is that the same pathogen does not necessarily produce the same symptom under every set of environmental conditions. Likewise, similar symptoms can arise from entirely different causes.
Temperature, humidity, water availability, substrate conditions, light, nutrition, plant age, and even the way a plant is cultivated can all influence how a disease develops and how its symptoms are expressed. In other words, the symptom we see is the product of an interaction between the host, the pathogen, and the environment. Change any one of those components, and the resulting disease can change dramatically. This recent begonia case is a particularly useful reminder of this principle.
Root-knot nematodes are well known for their belowground symptoms, but reports of rare and isolated cases of infections on aerial plant tissues, including stems, leaves, and flowers, are reported in only one publicly available extension bulletin from 1985. These symptoms remain unusual and have rarely been observed unless aerial tissues are artificially inoculated, and they have only been documented in a limited number of hosts.
So, when confronted with the unusual stem symptoms in a begonia, it would be easy to focus exclusively on the appearance of the tissue and pursue diagnoses such as oedema or crown gall. These plants were being cultivated in enclosed, high-humidity conditions, where moisture levels around the plant were substantially different from those experienced by a plant growing in a more open environment. Such conditions can alter transpiration rates, water movement, tissue hydration, pathogen development, and the plant's own physiological responses. They also give rise to the wet, humid conditions necessary for oedema to develop or crown gall bacteria to thrive.
The small root galls were an important clue. Microscopic examination then provided the confirmation: eggs, juveniles, mature females, and the characteristic giant cells associated with root-knot nematode feeding. These signs of RKN were found in both the root and stem swellings. Understanding the environment in which the hosts were being grown, with its high moisture conditions, then provided supporting evidence that the nematodes had favorable environmental conditions to migrate into much higher foliar tissues than is typically seen in RKN infestations and produce an unusual symptom. Swollen galls on the stem told us that something was wrong, and if we relied on the most common culprits associated with this symptom alone, namely oedema or crown gall, we would have gotten the diagnosis wrong.
The begonia case is a fascinating example of how flexible disease expression can be. A pathogen with a reputation for being almost exclusively soilborne and producing galling symptoms on root tissues, under particular host and environmental circumstances, can be associated with symptoms in tissues where we do not ordinarily expect to find them.
Ultimately, environment is not simply a backdrop against which plant disease occurs. It is one of the determinants of how disease develops, how severe it becomes, and critically for anyone trying to ID the pathogenic cause, what it looks like.
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:
Christopher Detranaltes, Ph.D.
Cooperative Extension – Yuma County
Email: cdetranaltes@arizona.edu
Cell: 602-689-7328
6425 W 8th St Yuma, Arizona 85364 – Room 109
Last week, we initiated an on-farm demonstration of soil steaming of the season with our self-propelled steam applicator. The machine is designed to inject steam into the soil and raise soil temperatures to levels sufficient to kill weed seed and soil borne pathogens (roughly 150°F for > 20 minutes). After the soil cools (< ½day), the crop is planted into the disinfested soil.
In this trial, we are examining the viability of soil steaming for controlling weeds in spinach at the field scale level (plot size > 1/3rd ac). The machine performed well in that it was able to reach target soil temperatures at reasonable travel speeds (> 0.25 mph) in cold soil (roughly 50°F), provide uniform temperature distribution across the bed and form nicely shaped beds suitable for subsequent planting. Stay tuned for reports of weed control efficacy, crop yield and overall profitability as compared to the grower standard.
If you are interested in seeing the machine operate at the field scale level on a commercial farm, we are conducting additional trials this week! Please contact me for further information.
Fig. 1. On-farm demonstration of a self-propelled steam applicator for weed and
diseasecontrol video. We are conducting additional trials this week. Contact me if
you are interested in seeing it.
Acknowledgements
This project is sponsored and funded in part by the Arizona Specialty Crop Block Grant Program and the Propane Education and Research Council (PERC). We greatly appreciate their support.
1. Precision Robotic Weeding and Thinning Trial
We are approaching the final steps of our ongoing robotic weeding and thinning trial for head lettuce. As the crop approaches maturity, we will soon conduct a comprehensive comparison of lettuce marketable yield between robotic-treated and handweeded/thinned plots.
These results will provide evidence-based insights into the efficacy and viability of robotic technologies in specialty crop production. Our preliminary observations suggest promising results, and we anticipate that detailed findings will be valuable for adoption decisions across the region.
Southwest Ag Summit Presentation
Join us at the Southwest Ag Summit on February 19th for a detailed presentation of our results. This session will provide the complete analysis to support grower decision making.
Funding Acknowledgment: This research was made possible through support from the Arizona Iceberg Lettuce Research Council (AILRC).
2. Precision Chemigation Trial
In parallel with robotic thinning and weeding research, we are advancing precision chemigation through the utilization of a custom injection assembly designed to accurately deliver chemicals like herbicides and pesticides into sprinkler irrigation systems for research purposes.
The chemigation assembly enables consistent, controlled injections at different rates, allowing for optimized chemical efficacy.
The chemigation trial will evaluate the efficacy of Kerb and Prefar herbicides applied at different rates through the chemigation system for head lettuce. This research will provide weed control efficacy optimized for chemigation delivery methods. We will present details on the chemigation system and herbicide efficacy during the IPM Session at the Southwest Ag Summit.
Funding Acknowledgment: This project was funded in part by the USDA National Institute of Food and Agriculture through the Western Integrated Pest Management Center.
Both projects represent important steps forward in the adoption of precision agriculture technologies for sustainable crop production. Results from both trials will be presented at the Southwest Ag Summit on February 19th.
For questions or to schedule a farm visit to view either trial, please contact Mazin Saber at mazinsaber@arizona.edu or cellphone# (352)870-8994. Stay tuned for the results!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:
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:
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.
