Rapidly changing conditions are a common feature in the agricultural arena.  Things are in a constant state of flux in terms of climate, economics, methods of operation, etc.  However, in the past few years, principally during the pandemic and post-pandemic times, changing conditions in agriculture for the desert Southwest have been extremely rapid and substantial.
 
Supply chain issues have been disruptive to many sectors of the economy and that has certainly affected agricultural operations.  Things that have commonly been standard or easy things to manage in the past such as the simple need of replacing equipment or parts have become complicated and expensive.  
 
We have become aware of fragile supply chains and the exposure of single points of failure that can have huge domino effects in many facets of our society, including agricultural industries.  For example, during the pandemic it cost nearly $40,000 to move a shipping container from Asia to the U.S. and now things are starting to catch up and it has been reported that containers can now be shipped from Asia to the U.S. for less than $3,000.00.  
 
Fertilizer prices for many materials have more than doubled in recent years, primarily due to basic supply and demand pressures.  Fertilizer supplies have been subject basic economic pressures and further exacerbated by the war in Ukraine and the associated changes in natural gas supplies.  
 
Fertilizer Supply and Cost
In a recent report from DTN market analysis (Formerly: Telvent DTN, Data Transmission Network) for the second week of November, retail U.S. fertilizer prices were not substantially different than in October but did have some slight variations with five fertilizers showing marginally lower prices than in October and three other key fertilizers tracking slightly higher.  It is important to note that DTN designates a “significant” difference in prices with a move of 5% or more.
 
The five fertilizers that were marginally lower in price included monoammonium phosphate (MAP), potash, urea, 10-34-0, and anhydrous ammonia.  Di-ammonium phosphate (DAP), urea ammonium nitrate (UAN)-28, and UAN-32 were slightly higher in price in mid-November, Table 1.  Costs per pound of nitrogen (N) is shown for primary N sources in Table 2.

MAP	Potash	Urea	10-34-0	Anhydrous	DAP	UAN-28	UAN-32
$978	$848	$812	$753	$1,415	$930	$584	$681

Table 1.  Mid-November retail prices in U.S. markets for several fertilizers.  Source: DTN
 

Anhydrous Ammonia	UAN-28	UAN-32
$0.88	$1.04	$1.06

Table 2.  Comparative prices per pound of N.  Source: DTN
 
Crop commodity prices have been higher recently, sometimes to the extreme.  However, the increasing costs of crop production have generally overrun the increasing returns on a strong market.  In a recent report on western crop production conditions, estimates of cost of production increases in the past year are 135% higher than in 2020 while the return values to farmers have been about 127% higher.  Thus, a nearly 10% negative differential exists which exerts a strong impact on the crop production systems of the desert Southwest.
 
The American consumer is seeing this as well.  In the American Farm Bureau Federation’s 37th annual cost survey from volunteer shoppers for Thanksgiving dinner has shown that prices are up 20% this year.  This increase is in addition to the 14% increase experienced in 2021.
 
Nutrient Management
Developing a conservative approach to nutrient management is often considered a risky venture in crop production systems, particularly with a short season crop like a leafy green vegetable that has a premium on quality as well as yield.  However, under high fertilizer price conditions and/or tight supply, there is a greater incentive to develop and employ a more conservative approach to nutrient management.
 
To maximize nutrient management efficiency, the 4R concept of plant nutrient management and application can be helpful.  The 4R concept consists of applying:
 
 1.   Right fertilizer source at the
 2.   Right rate, at the
 3.   Right time and in the
 4.   Right place
 
Along with the 4R nutrient management approach, assessing plant-available forms of the nutrients present in the soil by evaluating soil tests with appropriate indices is a good step in the develop of a more efficient nutrient management program.  Then splitting nutrient applications, particularly mobile nutrients such as N in line with crop uptake and utilization are good steps towards higher fertilizer use efficiency by the crop.  Thus, timing, methods, and rates of nutrient applications are critical (e.g, 4R management).
 
In agriculture we know quite well that we have no control over markets and the costs of crop production inputs.  However, we can control these inputs in the field, and we do have some tools at our disposal that can be helpful in the process.

It’s unfortunately a very great season to be a plant pathologist…

We have confirmed the first sample of Fusarium wilt on lettuce submitted to the Yuma Plant Health Clinic from Yuma County. The stunted seedlings looked like any other typical case of damping-off at the seedling stage. When plated on culture media, subsequently confirmed Fusarium colonies grew abundantly from the declining plant tissues. If you’re not already on guard and scouting, this is a warning that Fusarium is active in Yuma County.

Adding on to this early alert, we’ve received a surge of submissions of young brassicas to the clinic. Several severely wilted and declining plants from around Yuma County have cultured positive for Pythium, likely as an opportunistic invader coming in on the back of all the early-season rain that brought stress to seeds and young transplants. Growers may want to consider oomycides, but only if the seedling disease is first confirmed to be Pythium. Remember, many seedling diseases caused by true fungi are indistinguishable from those caused by Pythium.

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

As mentioned in a previous article, last month at the UC Cooperative Extension Automated Technology Field Day in Salinas, CA, several automated technologies were showcased operating in the field for the first time to a general audience. One of the “new” machines designed specifically for in-row weeding in vegetable crops was discussed previously, a second is highlighted here.
Vision Robotics¹ (https://www.visionrobotics.com/) demoed an innovative mechanical in-row weeding machine (Fig. 1). As with most other automated weeding machines currently on the market, in-row weeds are controlled with knife blades that cycle in and out of the crop row. Each knife blade however is controlled independently by an electric motor rather than in coupled pairs. Another feature is that the imaging system calculates a prescribed path for the blades to follow based on a contour of the crop plant and a user defined offset distance from the contour (Fig. 2) Because electric motors are used, blade position can be continuously and precisely controlled, thus facilitating close cultivation.
In the demo, the prototype seemed to work pretty well, but the run was short, and it was difficult to fully evaluate its performance. The video they shared of their imaging system with path planning and blade movement operating in real time impressed and showed good promise (Fig. 2). The innovation was recently patented, and the company is planning commercial units for interested customers.
Developments such as these are worth investigating as our and other researchers’ studies have shown that automated in-row weeding machines control about 50-66% of the in-row weeds, and the majority of uncontrolled weeds were observed to be close to the crop plant (Lati et al., 2016; Mosqueda et al., 2021).

References
Lati, R.N, Siemens, M.C., Rachuy, J.S. & Fennimore, S.A. (2016). Intrarow Weed Removal in Broccoli and Transplanted Lettuce with an Intelligent Cultivator. Weed Technology, 30(3), 655-663.
Mosqueda, E., Smith, R. & Fennimore, S. 2021. 2020 Evaluations of automated weeders in lettuce production. ANR Blogs. Davis, Calif.: University of California Davis. Available at: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=45566.

Acknowledgements
A special thank you to Tony Koselka, Vision Robotics Inc., for uploading the videos referenced in this article.
____________________
[1] Reference to a product or company is for specific information only and does not endorse or recommend that product or company to the exclusion of others that may be suitable.

Fig. 1. Prototype in-row weeding machine developed by Vision Robotics¹ demonstration at UCCE Automated Technologies Field Day. Clear here  or on the image to view the machine in action.


Fig. 2. Plant contour and cultivating blade path planning of prototype in-row weeding machine developed by Vision Robotics¹. A contour of the crop plant is traced (left) and a prescribed path a user defined distance from this contour (right) is determined for the blade tips to follow. Clear here  or on the image to view the system in action.

We have established some experiments at the Yuma Agricultural Center to evaluate herbicides in lettuce transplant. The purpose of the trials was to determine Crop safety and weed control in our desert conditions as well as targeting the weed species present in the area. One of the herbicides tested is DCPA (Dacthal).
DCPA (dimethyl tetrachloroterephthalate) is an herbicide that was first registered in the United States in 1958⁽¹⁾ and was among the first herbicides tested in lettuce. It has been used pre-emergence and established turf, ornamentals, and brassica crops, cucumbers, beans, melons, garlic, greens, squash, horseradish, eggplant, onions, yams, tomatoes, peppers, potatoes, strawberries, and cotton. DCPA Controls several annual broadleaves and grass weeds⁽²⁾.
A broadcast application of DCPA was done Pre and Post-transplant at the rate of 7pt/a with a CO₂ Backpack R&D sprayer at the volume of 20 gallons per acre and with 8002 VS flat fan nozzles. 
We observed in our trial that DCPA at the rate of 7pt/a was safe to transplanted iceberg lettuce (variety Bubba), and showed similar control of Purslane as Pronamide (Kerb) at the rate of 2 pt./a.
Would you like to see more results from our evaluations with other products such as Prowl H₂O, Dual Magnum, Facet, and Kerb?
You are invited to come and have a conversation with us in our 2022 Lettuce Crop Losses Workshop TODAY AT 11:30 AM at the Yuma Agricultural Center. Lunch is on us provided by the University of Arizona Pest Management Center.

This time of year, John would often highlight Lepidopteran pests in the field and remind us of the importance of rotating insecticide modes of action. With worm pressure present in local crops, it’s a good time to revisit resistance management practices and ensure we’re protecting the effectiveness of these tools for seasons to come. For detailed guidelines, see Insecticide Resistance Management for Beet Armyworm, Cabbage Looper, and Diamondback Moth in Desert Produce Crops .

VegIPM Update Vol. 16, Num. 20

Oct. 1, 2025

Results of pheromone and sticky trap catches below!!

Corn earworm:  CEW moth counts declined across all traps from last collection; average for this time of year.

Beet armyworm: BAW moth increased over the last two weeks; below average for this early produce season.

Cabbage looper: Cabbage looper counts increased in the last two collections; below average for mid-late September.

Diamondback moth: a few DBM moths were caught in the traps; consistent with previous years.

Whitefly:  Adult movement decreased in most locations over the last two weeks, about average for this time of year.

Thrips: Thrips adult activity increased over the last two collections, typical for late September.

Aphids: Aphid movement absent so far; anticipate activity to pick up when winds begin blowing from N-NW.

Leafminers: Adult activity increased over the last two weeks, about average for this time of year.