Improvements of irrigation and crop water management are always central to any discussions in the agricultural communities of the desert Southwest regarding higher crop production efficiencies.  That is particularly true in these days of water shortages.
In any crop production setting the crop (plant)-soil-water relationships are essential to producing a healthy and productive crop.  In desert agriculture, water is our first limiting agronomic (crop and soil) factor and there is no substitute for that.
Amid all the discussions about improvements in irrigation efficiency, the focus on plant-soil-water relations needs to be continually emphasized.  The objective of any irrigation system is to provide adequate irrigation water to the soil for the benefit of the crop.  Thus, it is important to understand the soil conditions and the actual crop-water needs for each irrigation event.

Every combination of a soil and a specific crop is unique, and that delicate relationship is compounded by the above ground environment the plant is growing in, the meteorological conditions.  The dynamics of crop-water demand change with each plant species and it will vary daily within a given crop in response to soil conditions, stage of growth, and meteorological conditions, i.e., temperature, humidity, wind speed, solar radiation, etc.   These meteorological factors must be appropriately considered for efficient irrigation management, irrespective of any type of irrigation system, i.e., flood, sprinkler, drip, etc.
In Arizona we are fortunate to have the Arizona Meteorological Network (AZMET) in place and fully operational with high quality data being collected from agricultural areas across the state on an hourly basis.  At present, this data is summarized daily from 25 agricultural sites and seven urban sites across the state.  https://ag.arizona.edu/azmet/

Dr. Paul Brown, Extension Specialist in Biometeorology (retired) began the development of the AZMET system in 1985 and the full operation of the system began in January 1986.  Prior to his retirement a few years ago, Dr. Brown managed and directed the AZMET system along with a robust research and Extension education program to provide numerous crop production tools that this system supports.  Together, Paul Brown and Bruce Russell developed an excellent weather system that is available to us all.   Dr. Jeremy Weiss now directs the AZMET program.

The meteorological data collected by AZMET include temperature (air and soil), humidity, solar radiation, wind (speed and direction), and precipitation.  AZMET also provides a variety of computed variables, including heat units (degree-days), chill hours, dew point, and reference crop evapotranspiration (ETo).  AZMET data are summarized in a variety of formats, including several ready-to-use summaries and comma-delimited (raw) ASCII text files that can be imported into most database and spreadsheet programs (Russell, 2011).
I have participated in numerous discussions recently regarding efforts to manage water resources in a broad sense, such as within an area or district, as well as in individual crop fields where the use of satellite-based evaporation (ET) estimates are being considered for application.  In Arizona, that should not be necessary since we have AZMET stations on the ground that are well-placed in agricultural areas with high quality data available daily.  The AZMET system provides direct measurements of daily atmospheric conditions that our crops are dealing with in each of the 25 locations.

With AZMET and the information directly available and accessible, in my view we should be using this system for our weather-based needs for crop management and not a remote satellite system.  Even if someone insists on using satellite-based systems, it will need ground truthing and AZMET data would be essential for that.
We should be using the AZMET data and related crop management tools.  This system has been developed by the University of Arizona Cooperative Extension System and it is openly available for direct access and use.

References:
Russell, B. 2011.  AZMET.  The Arizona Meteorological Network : A Brief Overview.  University of Arizona Cooperative Extension.  https://ag.arizona.edu/azmet/azmet04.htm

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

At the 2023 FIRA USA Robotics and Autonomous Farming Solutions Forum last month, some of the latest automated and robotic technologies were demonstrated in the field. Several of the weeding technologies demonstrated are brand new to the U.S. and/or Yuma, AZ area. These included a 5.6 inch² (2.4 x 2.4 inch) resolution fixed boomed spot sprayer (Fig. 1), a high precision, “turret gun” spot sprayer  (Fig. 2) and a mechanical weeder that utilizes a unique rotating blade design and lidar for depth control (Fig. 3). Although the test runs were short, I was impressed with the performance and possibilities of these machines. Company representatives said that they would be traveling to Arizona for the season and would like to meet with growers interested in their technology. Company contact information can be found at their respective websites, or feel free to contact me if you would like additional information.

Fig. 1. Ecorobotix¹ (Yverdon-les-Bains, Switzerland) precision weeding machine
demonstration at 2023 FIRA USA. The unit has modular, 6.6’ wide spray booms
equipped with 156 individually controllable spray nozzles to spot spray weeds
(top right). A vision system is used to detect weeds and spot spray resolution is
2.4 x 2.4 inches. Darker soil indicates where spray (water) was delivered to
targeted weeds (bottom).



Fig. 3. GreenTech Robotics’ Weed Spider¹ (Kelvin Grove, New Zealand)
demonstration at 2023 FIRA USA. The unit is equipped with a vision system for
detecting crop plants and weeds, and blades that move in and out of the crop row
to remove in-row weeds. Lidar sensors are used to create a 3-D image of the soil
surface and control cultivating blade depth.

---

[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.

When I think about Lipid Biosynthesis Inhibitor herbicides, Post (sethoxidim) and Select (clethodim) come to my mind. A great description of these type of herbicides can be found at the Section VI of the Arizona Pest Control Advisor (PCA) Study Guide. They say a good teacher can explain complicated things in a simple way. Please read this explanation by Barry Tickes:

“These herbicides are known as ACCase inhibitors because they inhibit the production of acetyl-coenzyme A carboxylase (ACCase) which is an enzyme needed in the first steps of lipid or fatty acid production. Lipids are needed in the production of new membranes which, among other things, are needed in the production of cell walls. These chemicals move from the foliage to the growing points, only kill grasses, and have very little soil activity. Grasses stop growing immediately and slowly turn chlorotic or red and die usually in 7 to 21 days. These products are used to selectively kill grasses in broadleaf crops".
 

Classification	Common Name (s)	Commercial names	Arizona crop registrations
Aryloxphenoxy Propionates	fluazifop fenoxaprop clodinafop diclofop	Fusilade Puma, Acclaim, Option, Whip Discover Hoelon	Small grains, Cotton, trees & vines, Several broadleaf crops
Cyclohexanediones	sethoxydim clethodim tralkoxydim	Poast, Segment, Vantage, others Select, Arrow, Prism, Envoy, Intensity, Volunteer, Trigger, Section, others Achieve	Alfalfa, cotton, Several broadleaf Crops Small grains

 
You need to see this .. time lapse photography shows the symptoms of Poast herbicide to wheat.

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.