We conducted a session at the 2026 SW Ag Summit program on Thursday, 19 February regarding the future of the Colorado River and possible management plans for water allocations that will be very important for agriculture in the lower Colorado River Valley in the next decade. The program outline included the following speakers and components:
All current conservation and operational guidelines expire in 2026. The Department of Interior (DoI) and the Bureau of Reclamation (BoR) set 11 November 2025 as a deadline for basin states (Figure 1) to come forth with an agreement and a new plan for conservation and river management. But the basin states could not come to an agreement, so the DoI extended the deadline to 14 February 2026, and the basin states failed to reach an agreement and meet that deadline.
Figure 1. Map of the Colorado River Basin and watershed. (Source: U.S. Bureau of
Reclamation).
During the SW Ag Summit session prospects for a possible agreement among the Colorado River basin states were discussed. The Lower Basin (LB) states are unified in their efforts to find a common agreement and have offered numerous plans that include substantial conservation reductions on their part, but the Upper Basin (UB) states are unified in their direct opposition to any offers made by the LB and they refuse to make any reductions in their water allocations.
In January 2026, the Bureau of Reclamation BoR published the Draft Environmental Impact Statement (DEIS), which is required in the NEPA process. The DEIS includes five alternative approaches and analyses for consideration in the development of the new operating guidelines.
The five alternative approaches are listed below in very brief terms.
A lot of attention at our SW Ag Summit session was directed at a review and consideration of the five alternatives presented in the DEIS. Figure 2, which describes LB and UB reductions associated with each of the DEIS alternatives plus two others (continued current strategies and supply driven pro-rata), was presented and reviewed. It is important to note the significant reductions from each alternative on the LB allocations while the UB is not subject to any reductions.
Figure 2. Maximum shortages for the Lower and Upper Basins for a series of
possible alternatives. (source: Arizona Reconciliation Committee).
The possible impacts from the DEIS alternatives being considered are both interesting and puzzling considering the contrasting UB and LB facts (Figure 3). Some of the basic facts associated with the economic impact of the use of the Colorado River water include:
The UB states have never utilized their complete allocation of 7.5 MAF of Colorado River water while the LB has consistently utilized their 7.5 MAF and put it to good work (Figure 3). Yet the UB states have been insistent on not making reductions on their part and insisting that all future reductions come the LB.
A huge amount of infrastructure has been developed in the LB in the past 100 years to facilitate the development and productivity described in Figure 3, all in partnership with the United States via the DoI and BoR, Good examples include: the Boulder, Glen Canyon, Parker, Davis, Palo Verde Diversion, and the Imperial Dams as well as the Colorado River Aqueduct and the Central Arizona Project. In review of the DEIS, the proposed alternatives do not seem consistent with the historical precedent established by the DoI and BoR in recognizing the value of the Colorado River in the LB.
Figure 3. Some basic Colorado River basin facts. (Source: Coalition for Protecting
Arizona’s Lifeline, Colorado River Facts.
https://protectingarizonaslifeline.com/members/)
Public input is critical to shape long-term water management for Lake Mead and Lake Powell. Comments have been openly solicited from citizens on the DoI DEIS for Post-2026 Colorado River operations via email to crbpost2026@usbr.gov The deadline was 2 March 2026. However, most of the deadlines imposed by the DoI and BoR for proposals from the basin states have passed without consequence, so perhaps they will extend the period for public comments as well.
The DEIS proposed alternatives can be accessed at the Bureau of Reclamation website. Also, a Web Tool has been developed to help explore and understand different operational strategies: Post-2026 Operations Exploration Web Tool .
Given an opportunity, it is also important to attend meetings hosted by the BoR, which are designed to provide information and collect public input.
We have recently seen an increase in celery samples coming into the clinic presenting with symptoms including elongated necrotic pitting with significant horizontal cracking on the inner stalks and sometimes total breakdown of the young tissues (petiole and leaf) within the heart. In these same samples, the outer stalks and leaves appear healthy and unaffected.
At first glance, these symptoms resemble several known issues in celery, including black heart caused by calcium deficiency, black streak caused by boron deficiency, cucumber mosaic virus (CMV), and lygus feeding injury. Field observations have consistently shown low-to-absent lygus populations despite widespread incidence of severely affected celery, making insect damage an unlikely primary cause. CMV can also cause sunken, buff-colored lesions on the stalks but typically presents with additional foliar symptoms including leaf cupping and discoloration. Also, CMV doesn’t discriminate between young and old tissues, and despite testing every sample the YPHC has received thus far we have failed to detect the presence of the virus in any of the samples.
Furthermore, I have had the chance to walk two severely affected fields in-person, from which I found two consistent observations. First, these symptoms are observed uniformly throughout large sections or the entirety of the field, a distribution pattern which is atypical of a sudden outbreak of a biotic pathogen or insect pest. Second, hosts from different plantings showed uniform severity, which indicates the issue arose at the same time across celery in the area. These two observations suggest that an abiotic culprit rather than a biotic pest is to blame for this sudden eruption of host symptoms.
So with lygus and CMV being unlikely causes and consistently negative cultures for any other bacterial or fungal causes, the last two options that fit the symptoms of these samples are both abiotic in nature. Black heart is a physiological disorder most frequently associated with calcium deficiency. The internal hearts of celery with black heart experience significant breakdown of all tissues due to insufficient calcium transport, similar to what can be observed on tomatoes with blossom end rot. Black streak, similarly, is also a physiological disorder, however, it is most often associated with boron deficiency. Black streak typically presents as elongated, sunken lesions along petioles and stems with significant crosswise cracking along the petioles. However, development of brown areas and die back in black streak cases has also been reported.
Figure 1. Early blackheart symptoms
Figure 2. Late blackheart symptoms + secondary colonization
Figure 3. Black streak of celery
Both disorders can arise from inadequate fertilization of either calcium or boron or when rapid growth outpaces the plant’s ability to uptake enough of these nutrients from the soil. Both conditions have been linked to several causal environmental factors, but they commonly develop into severe losses when celery is grown in elevated temperatures above 90°F.
With black streak, greenhouse studies demonstrated that susceptibility was not uniform over time and that the highest susceptibility in celery is observed during the rapid growth phase, about 4-7 weeks after transplanting (Ngouajio 2012). During this period of rapid growth and development boron demand may not be met when the growth of aboveground tissue is further stimulated by hot weather.
When celery is affected by blackheart, it often develops the most severe symptoms as plants approach maturity. This disorder is more frequently associated with rapid fluctuations in soil moisture from drought to flood conditions, excessive fertilization or soil fertility levels of nitrogen and potassium, and high soil salinity.
Of the cases submitted to the YPHC so far, both have been occurring at roughly equal frequencies.
Sources and further reading:
Ngouajio, M.. “Hot weather requires careful management of celery to avoid black streak disorder”. Michigan State University Extension. 2010. URL: https://www.canr.msu.edu/news/hot_weather_requires_careful_management_of_celery_to_avoid_black_streak_dis
Guan, W.. “Picture of the week: Blackheart of celery”. Purdue University Extension Plant and Pest Diagnostic Lab. 2022. URL: https://ag.purdue.edu/department/btny/ppdl/potw-deptfolder/2022/blackheart-of-celery.html
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
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:
Precision robotic weeding/thinning system costs:
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:
Consider service-based (RaaS) or rental/leasing robotic systems if:
Stick with traditional hand operations if:
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:
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.
In a previous IPM Veggie Newsletter post, the figure labeling was published incorrectly. We apologize for the technical issues and are reposting the corrected reference and a brief recap focused only on the monthly average maximum air temperature (Tmax). Using the AZMET Yuma Valley station record (1987–2025), the figure for monthly average Tmax shows a gradual warming signal through time, with substantial year-to-year variability. The fitted linear trend indicates:
Why it matters: From an agronomic and IPM perspective, a warmer Tmax baseline can contribute to faster degree-day accumulation, earlier crop development, and shifted timing of field operations and pest phenology. Even with large variability, the long-term direction supports continued use of temperature-based planning (degree-day tracking) to align scouting and management actions with development rates.
Figure 1. Distribution and long-term trend in monthly average maximum air
temperature (Tmax) at the AZMET Yuma Valley station (Yuma Valley, AZ) for 1987–
2025.
Tomorrow at the Southwest Ag Summit: Organic Practices (9:30–11:30 AM)
Tomorrow (Thursday, February 19, 2026) at the Southwest Ag Summit 2026 in Yuma, don’t miss the Organic Crop Production Methods seminar block (AS 113), running 9:30–11:30 AM. If you’re looking for practical, field-ready ideas to improve yield, strengthen soil health, and increase water-use efficiency in desert vegetable systems, this is one of the most relevant sessions on the program.
This fast-moving series brings together applied research and industry experience around what matters most in organic and transitional production under arid-region constraints: high pH/calcareous soils, salinity risk, intense evaporative demand, and tight irrigation windows. Presentations will emphasize organic fertility strategy and soil health–centered management, highlighting approaches that can translate into measurable gains in crop performance through improved nutrient availability, better infiltration and moisture retention, and management pathways that support root vigor and stress resilience.
Thursday presentations (9:30–11:30 AM)
Program details: https://yumafreshveg.com/southwest-ag-summit/#FEB19
