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.

I hope you are frolicking in the fields of wildflowers picking the prettiest bugs.

I was scheduled to interview for plant pathologist position at Yuma on October 18, 2019. Few weeks before that date, I emailed Dr. Palumbo asking about the agriculture system in Yuma and what will be expected of me. He sent me every information that one can think of, which at the time I thought oh how nice!

When I started the position here and saw how much he does and how much busy he stays, I was eternally grateful of the time he took to provide me all the information, especially to someone he did not know at all.

Fast forward to first month at my job someone told me that the community wants me to be the Palumbo of Plant Pathology and I remember thinking what a big thing to ask.. 

He was my next-door mentor, and I would stop by with questions all the time especially after passing of my predecessor Dr. Matheron. Dr. Palumbo was always there to answer any question, gave me that little boost I needed, a little courage to write that email I needed to write, a rigid answer to stand my ground if needed. And not to mention the plant diagnosis. When the submitted samples did not look like a pathogen, taking samples to his office where he would look for insects with his little handheld lenses was one of my favorite times. 

I also got to work with him in couple of projects, and he would tell me “call me John”. Uhh no, that was never going to happen.. until my last interaction with him, I would fluster when I talked to him, I would get nervous to have one of my idols listening to ME? Most times, I would forget what I was going to ask but at the same time be incredibly flabbergasted by the fact that I get to work next to this legend of a man,  and get his opinions about pest management.  Though I really did not like giving talks after him, as honestly, I would have nothing to offer after he has talked. Every time he waved at me in a meeting, I would blush and keep smiling for minutes, and I always knew I will forever be a fangirl..

Until we meet again.

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.

Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:             
CEW moth counts remain  at low levels  in all areas, well below average for this time of year. 
 
Beet armyworm:          
Trap increased areawide; about average compared to previous years.
 
Cabbage looper:          
Cabbage looper counts increased to seasonal highs; slightly below average for this time of season.
 
Diamondback moth:      
DBM moth counts decreased in most areas. About average for this time of the year.
 
Whitefly:                      
Adult movement negligible, average for late winter. 
 
Thrips:                          
Thrips adult counts increased in south Gila Valley, down in all other locations. Below average compared with previous years.
 
Aphids:                        
Aphid movement decreased in all area; below average for mid-March.
 
Leafminers:                  
Adults remain low in most locations, average for March.