In Arizona, the diamondback moth (DBM) is typically considered a minor pest that occasionally builds up to damaging levels in the winter and spring. In most years, growers can easily control the pest with 1-2 well timed insecticide sprays. But in the fall 2016 outbreaks of an invasive DBM population occurred throughout all vegetable growing regions in Arizona where it was determined that the source of the DBM originated from infested transplants grown in desert greenhouses. We later discovered that the invasive DBM population was very resistant to the diamide insecticides (Coragen, Beseige, Belt and Vetica). The DBM infestations experienced by Arizona growers in 2016-17 were not anticipated, and overall, the resistant pest caused serious economic losses in cole crops. Prior to the 2017-18 growing season, PCAs and growers were very apprehensive about the resistant DBM reappearing on their fall crops. However, the population abundance of DBM in the desert last season was significantly lower than what was observed under widespread outbreak conditions in 2016. We received no complaints from PCAs or growers of uncontrollable DBM infestations, crop damage or yield losses in 2017, and PCAs reported having no difficulty controlling larvae or adults with commonly used insecticides, including the diamides. Field trials and lab bioassays conducted at the Yuma Ag Center confirmed the local DBM populations were susceptible to these insecticides. Field inspections of transplants yielded no larvae on plants arriving from local and coastal nurseries. Thus, we have concluded that the DBM that appeared in 2017-18 were a distinctly different population than those that infested crops in the fall of 2016. It is likely that the DBM population in 2017 migrated onto both direct-seeded and transplanted cole crops in wind currents following September storms. In an attempt to document the impact of the DBM outbreaks on Arizona cole crops, we conducted a two-part survey of growers and PCAs from Yuma, Maricopa and Imperial Counties in May 2018 to (1) estimate the severity of yield losses from DBM on direct-seeded and transplanted cole crops, and (2) the intensity of chemical management required to control DBM, and associated level of control provided by each insecticide product used. To download a copy of the survey results, please go to Diamondback Moth on Desert Cole Crops in 2017.                         

As part of the SW Ag Summit that recently took place in Yuma, we conducted a breakout session on Thursday, 23 February 2023 titled “Colorado River Water Shortage: Agricultural Perspectives”.
This session provided a brief review of the background and current situation on the Colorado River and included perspectives from members of the lower Colorado River agricultural community including the Palo Verde Valley, Imperial Valley, and the Yuma area irrigation districts.   The program outline included the following participants:   
             
Colorado River Water Shortage: Introductory Overview      
                                    Jeff Silvertooth, University of Arizona, Tucson, AZ
 
Colorado River Water Shortage: Palo Verde Valley Perspective
Bart Fisher, Fisher Ranch, Blythe, CA           
 
Colorado River Water Shortage: Imperial Valley Perspective
                        Larry Cox, Lawrence Cox Ranches, Brawley, CA
 
Colorado River Water Shortage: Yuma Perspective
Elston Grubaugh, Wellton Mohawk Irrigation & Drainage District, Wellton, AZ 
 
Moderator:      Jeff Silvertooth
 


For geographic reference, Figures 1 and 2 provide maps of the lower Colorado River Valley and Yuma agricultural irrigation districts.
The session was not recorded but we do have each of the presentations available in the following links.
Jeff Silvertooth:
https://live-azs-vegetableipmupdates.pantheonsite.io/sites/default/files/2023-02/2023SWAS_JCS SWAS_ColoR Ag Perspectives_23feb23_FINAL_post.pdf
Bart Fisher:
https://live-azs-vegetableipmupdates.pantheonsite.io/sites/default/files/2023-02/2023SWAS_BF_SW%20Ag%20Summit%202023.pdf
Larry Cox:
https://live-azs-vegetableipmupdates.pantheonsite.io/sites/default/files/2023-02/2023SWAS_LC SWAS 23 February 2023.pdf
Elston Grubaugh:
https://live-azs-vegetableipmupdates.pantheonsite.io/sites/default/files/2023-02/2023SWAS_EG_02232023%20SW%20Ag%20Summit%20Panel_0.pdf
 
Also posted below is the link to an excellent video regarding Yuma Water and Ag that was recently developed and presented on 23 February by the Yuma Fresh Vegetable Association.
www.yumaagwater.com

Figure 1.  Map of the lower Colorado River including the dams, diversions,
and some of the major canal systems.



Figure 2.  Map of the Yuma area irrigation districts.   Source: Yuma Water Users Association, 2015.

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%). Spinach ‘Revere’ was seeded, then sprinkler-irrigated to germinate seed Jan 18, 2024 on beds with 84 in. between bed centers and containing 30 lines of seed per bed.  All irrigation water was supplied by sprinkler irrigation.  Treatments were replicated four times in a randomized complete block design.  Replicate plots consisted of 15 ft lengths of bed separated by 3 ft lengths of nontreated bed.  Treatments were applied with a CO₂backpack sprayer that delivered 50 gal/acre at 40 psi to flat-fan nozzles. 
 

Month	Max	Min	Average	Rainfall
January	68	42	54	1.14 in
February	73	47	59	0.50 in
March	77	50	63	0.31 in

 
Downy mildew (caused by Peronospora farinosa f. sp. spinaciae) was first observed in plots on Feb 19  and final reading was taken on February 26, 2024. Spray date for each treatments are listed in excel file with the results.   Disease severity was recorded by determining the percentage of infected leaves present within three 1-ft² areas within each of the four replicate plots per treatment.  The number of spinach leaves in a 1-ft² area of bed was approximately 144. 

The data (found in the accompanying Excel file) illustrate the degree of disease reduction obtained by applications of the various tested fungicides. Products that  provided effective control against the disease include Orondis ultra, Thrive 4 M, Fungout, Cevya, Eject and Zampro. No phytotoxicity was observed in any of the treatments in this trial.

At the 2023 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 autonomous orchard sprayer (Fig. 1a), wide span (4 and 6 row) automated weeders (Fig. 1b, Fig. 1c), steam applicators for pre-plant weed control (Fig. 1d) and post-emergent weed control/crop desiccation (Fig. 1e) and a camera guided cultivator (Fig. 1f). This trend towards developing wider and more productive machine machines is indicative of a maturing industry. It will be interesting to watch these machines evolve further and become integrated in our cropping systems.

Fig. 1. New pest control technologies demonstrated/on display at the 2023 Southwest Ag Summit Field Demo included a) mini GUSS¹ autonomous orchard sprayer, b) K.U.L.T.i - Select automated weeder, c) FarmWise’s Vulcan automated weeder, d) UC Davis/UofA band-steam applicator, e) X-Steam-inator’s steam applicator and f) Mantis Ag Technology’s camera-guided cultivator. (Photo credits Fig. 1d: Mazin Saber, University of Arizona)
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[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.

Thank you for attending the Weed Control breakout session at the Southwest Agricultural Summit last week. Dr. Jesse Richardson presented the historical perspective on how the methods of applying Pronamide have been developed. Some of this information can be found in the following links:
https://cals.arizona.edu/crop/counties/yuma/farmnotes/2003/fn0803kerblettuce.html
 
https://live-azs-vegetableipmupdates.pantheonsite.io/sites/default/files/2023-03/Kerb%20Word%20slides.pdf
 
   Also Dr. Samuel Discua presented an update on the Survey of Weeds as Reservoirs of INSV in Yuma County and the presentation can be found here: 
 
https://live-azs-vegetableipmupdates.pantheonsite.io/sites/default/files/2023-03/SWAG%202023%20Weeds%20Survey%20Update%20.pdf
 
Dr. Jose Carvalho shared with us results from his research program at the Maricopa Agricultural Center including evaluations with the “King of Weeds” Palmer amaranth.
 
Additionally, some information was presented on Prefar Chemigation as well as the effect on spinach plantings if planted too early. The trials were done this season at the Yuma Agricultural Center and The Arizona Cooperative Extension will make videos of these presentations available soon.

Area wide Insect Trapping Network   VegIPM Update, Vol. 15, No. 20, Oct 2, 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 decreasing in most areas, and below average for late September
 
Cabbage looper:          
Cabbage looper trap counts low in all locations, typical for mid-late September.
 
Diamondback moth:   
Adult activity beginning to pick up in Dome Valley.  Overall, typical of late September with minimal monsson activity.
 
Whitefly:                       
Adult movement most active in Dome Valley; overall below average for mid September
 
Thrips:                          
Thrips adult movement light; overall activity typical for 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.