Even though temperatures and humidity has dropped, worm pressure remains steady in most growing areas.   Here at the Ag Center, armyworm pressure is about average for early October, but still troublesome on new stands. Cabbage looper eggs and young larvae are now becoming abundant on all our crops, and PCAs are reporting an increase in looper pressure. Pheromone trap counts for armyworm and loopers remain below average in most areas. However, Diamondback moth larvae are unusually abundant on broccoli and transplants at the Ag Center.  I’ve had several PCA reports of diamondback pressure in transplanted and direct seeded brassica crops in the Wellton and Tacna areas. Trap catches have begun to increase also. So far, all insecticide products we’ve tested are providing good DBM control and no complaints from the field.  In one of my trials, the Verimark transplant tray drench treatment on cauliflower (Sep 5 wet date) was still active against DBM at 28 days following transplanting (see graph below).
 
Fortunately for local PCAs, several insecticide alternatives are available that provide excellent residual activity on these pests (see the Sept 20 update).   Perhaps equally important, many of the products have unique modes of action (MOA) that can be alternated throughout the growing season. This is important because the most fundamental way to reduce the risk of insecticide resistance is to eliminate exposure of multiple generations of Leps to the same MOA.   By using a different MOA on each subsequent spray application, you can minimize the risk of resistance by Lep larvae to these insecticide compounds. In contrast, repeatedly applying insecticide products with the same MOA for Lep control in the same area will significantly increase the risk of resistance.  This is particularly important with the Diamide group of insecticides (IRAC group 28). These products can be applied as both foliar sprays and soil systemic treatments, and currently 7 Diamide products are for use labeled in leafy vegetables - all with the same MOA (Coragen, Durivo, Besiege, Minecto Pro, Verimark, Exirel and Harvanta).  To avoid confusion among the Diamides, the IRAC group number (28) is placed on each label, adjacent to the product name.  Furthermore, applying a Diamide product (i.e., Coragen/Verimark) to the soil at planting or as a tray drench, and then subsequently applying Diamide foliar sprays (i.e., Harvanta/Besiege) on the same field is not a good idea as it can expose multiple generations of Leps to the same MOA.  For example, under ideal weather conditions, one could potentially expose 5-6 generations of BAW or DBM to the same MOA given the residual efficacy of the diamides.  That’s not a good way to use these products if you want them to remain effective.   Since the Diamides, as well as the other key products currently available (e.g., Radiant, Proclaim, Intrepid, Avaunt, Bts), are critical to effective management of Leps in leafy vegetables, PCAs should consciously avoid the overuse of any of these compounds. The most effective way to delay the onset of resistance by Leps in leafy vegetables is to consider the recommendations provided in the guidelines entitled Insecticide Resistance Management for Beet Armyworm, Cabbage Looper and Diamondback Moth in Desert Produce Crops.

 

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

This study was conducted at the Yuma Valley Agricultural Center. The soil was a silty clay loam (7-56-37 sand-silt-clay, pH 7.2, O.M. 0.7%). Variety: Deluxe (HMX2595) was seeded, then sprinkler-irrigated to germinate seed on March 20, 2024on 84 inches between bed centers. All other water was supplied by furrow irrigation or rainfall. Treatments were replicated five times in a randomized complete block design. Each replicate plot consisted of 25 ft of bed. Treatment beds were separated by single nontreated beds. Treatments were applied with a tractor-mounted boom sprayer that delivered 50 gal/acre at 100 psi to flat-fan nozzles spaced 12 in apart. 

Spray treatments were done on 05-21-2024, 05-31-2024, 06-07-2024 and 06-14-24. Powdery mildew was first seen on 06-05-24. Please see excel file for additional details.  

Disease severity of powdery mildew (caused by Sphaerotheca fuliginea and S. fusca) severity was determined 6-17-2024 by rating 10 plants within each of the four replicate plots per treatment using the following rating system: 0 = no powdery mildew present; 1 = one to two mildew colonies on leaves  ;2 = powdery mildew present on one quarter of leaves; 3 = powdery mildew present on half of the leaves; 4 = powdery mildew present on more than half of leaf surface area ; 5 = powdery mildew present on entire leaf. These ratings were transformed to percentage of leaves infected values before being statistically analyzed.

The data in the table illustrate the degree of disease control obtained by application of the various treatments in this trial. Most treatments significantly reduced the final severity of powdery mildew compared to nontreated plants. Quintec, Merivon, Tesaris, Luna Sensation, and V6M-5-14 V gave the best disease control. Phytotoxicity symptoms were not noted for any treatments in this trial.

ANR Webinar 10/17 click link for details.

At the 2024 Southwest Ag Summit Field Demo a couple of weeks ago, many of the latest technologies were demonstrated in the field. Most were related to pest control. Several of the technologies demonstrated or on display at the event are brand new to the Yuma, AZ area. The new technologies presented included an implement designed for cultivating high density crops (Fig. 1a), a field scale drone sprayer (10.6 gal) (Fig. 1b), a high precision spot sprayer (Fig. 1c) and a self-propelled machine that disinfests soil prior to planting using steam. Updated versions of laser weeders, camera-guided cultivators and smart, automated in-row weeding machines (mechanical) were also demonstrated. Over the next several years, it will be interesting to watch the technologies in this space evolve further and become integrated into our cropping systems.

Fig. 1. New pest control technologies demonstrated/on display at the 2024
Southwest Ag Summit Field Demo included a) Oliver¹ high density cultivator b)
DJI Agrospray T40 drone sprayer c) Ecorobotix ARA high precision spot sprayer
and d) UC Davis/University of Arizona self-propelled steam applicator for
disinfesting soil prior to planting.

[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.

The Southwest Agricultural Summit that recently took place in Yuma included a breakout session on Thursday, 21 February 2024 titled “New Developments in Weed Control”.
In this session Jose Antonio Cabrera representing BASF technical services for Coastal CA and Arizona provided a review of the new technologies being developed by his company in the Weed Control area. This includes new active ingredients as well as novel encapsulation technologies. The breakout session also included the lecture “Registration Support for Pest Management Tools in Specialty Crops, The IR-4 Project: Purpose and Process” by Roger B. Batts. “The IR-4 Project was established in 1963 by the U.S. Department of Agriculture to ensure that specialty crop farmers have legal access to safe and effective crop protection products. Helps growers address pest management concerns, develops data necessary for the registration of safe and effective pest management solutions with the U.S. Environmental Protection Agency¹.
Roger is the Weed Science biologist from the NC State University IR-4 headquarters. If you have questions such as: What is the IR-4 Mission? Why is IR-4 Needed? What are the programs within the IR-4 project? you will find some answers in the IR-4 Presentation Slides here.
We are currently conducting trials in Yuma in coordination with this project that could result in the addition of new labels and weed control tools for our Arizona vegetable growers.
Thank you for attending the SW Ag Summit Weed Science breakout session.
 
 
Reference:

1. https://www.ir4project.org/

 

Get your free copy of the Weed Seedling Identification Pocket Guide at the Yuma
Agricultural Center.

 

Area wide Insect Trapping Network   VegIPM Update, Vol. 15, No. 19, Sep 18,2024
 
Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:           
CEW moth counts low in most traps; below average for this early produce season. 
 
Beet armyworm:         
Trap counts high in Tacna and Wellton, and about average for early September
 
Cabbage looper:           
Cabbage looper trap counts low in all locations, typical for early September.
 
Diamondback moth:    
Adult activity not picked up in traps yet.  Overall, typical of early September with minimal Monsson activity.
 
Whitefly:                      
Adult movement most active in Dome Valley and S. Yuma Valley; overall below average for early September
 
Thrips:                          
hrips adult movement beginning to increase in Tacna and dome; overall activity typical for early September. 
 
Aphids:                         
Aphid movement absent so far; anticipate activity to pick up when winds beginning blowing from N-NW. 
 
Leafminers:                 
Adult activity light in all areas, about average for this time of season.