Compared to last year, Bagrada bug adult numbers have been relatively light on early broccoli plantings, and cauliflower/cabbage transplanted fields in the Yuma and Dome Valley. Furthermore, over the course of the summer, there have been very few reports of adults found in cotton, alfalfa, sudangrass and other seasonal crops relative to last summer. Does this suggest that Bagrada numbers will continue to be light once we get into September and acreage begins to increase. It's possible, but I wouldn't bet on it just yet. Remember, it wasn't until around mid-September last year when it seemed like the clouds opened up and Bagrada bugs dropped from the sky. PCAs and growers should not become complacent just because they aren't finding any Bagrada yet. Rather, it would be wise to assume they will eventually show up in some intensity, and you should prepare for them accordingly. Preliminary research conducted over the past year suggests that direct-seeded and transplanted crops are most susceptible to Bagrada bug infestations during stand establishment. Research to date also suggests that control of heavy Bagrada infestations with insecticides is the most economically viable option to protecting stands and preventing significant yield losses. This includes chemigation with pyrethroids, and using contact insecticides (pyrethroids, Lannate, Lorsban) once plants emerge and pipe is pulled. After stands are established and plant size increases up to the 3-4 leaf stage, or on growing transplants, PCAs may consider alternating to dinotefuron (Venom/Scorpion) for protecting plants from Bagrada feeding. This neonicotinoid will also provide knockdown of adult whiteflies and nymphs. More information on Bagrada bug control can be found in these research reports conducted in a 2010 field trial and in a 2011 greenhouse trial.

As part of the Southwest Ag Summit (SWAS) that took place in Yuma in late February, we conducted a breakout session on Thursday, 22 February 2024 titled “Colorado River Water Shortage: Agricultural Perspectives”.  
This session provided a brief review of the background, the current situation on the Colorado River, and very importantly it included an outlook on the current discussions among the basin states to negotiate a new compromise for the guidelines of use under conditions of water shortage.  These new guidelines will go into place at the end of 2026.  Both the upper and lower basin states have now submitted draft proposals to the Bureau of Reclamation (BoR) on 6 March 2024.
This breakout session at the Southwest Ag Summit provided up to date information and first-hand insight into the process.  The participants were each uniquely qualified to offer valuable perspectives on these issues.  
The participants included Elston Grubaugh, Wellton-Mohawk Irrigation and Drainage District, who introduced the discussion and served as program moderator.  Bart Fisher, Palo Verder Irrigation District and State of California Colorado River Water Board member, Fisher Ranch, Blythe CA, provided a California perspective with a background of extensive experience in Colorado River management over several decades.  Hank Auza, Yuma County Water User’s Association President and Yuma Ag Water Coalition representative, Barkley Co. of Arizona, Yuma AZ, provided an Arizona perspective.  
Elston has extensive experience working in irrigation districts on both the California and Arizona sides of the Colorado River.  He has a valuable perspective, and he plays an important role in the management of Colorado River water in the Yuma area.  We are fortunate to have Elston provide his direction for this program and offer his point of view.
Both Bart and Hank are directly involved in the ongoing reconsultation negotiations directed at developing the new Colorado River management guidelines that will go into place in 2026.  Both are part of their state's delegation in the current negotiations and represent the lower basin.  Bart and Hank are not only responsible for representing California and Arizona, but they are both active farmers in the Palo Verde Valley and Yuma area valleys, and they bring valuable perspectives to the discussions.
The goal of negotiations among the seven U.S. Colorado River basin states has been to submit a single document proposing guidelines to the BoR.  However, as was discussed at this program at the SWAS, the upper and lower basin state groups have been dealing with significant differences and were not able to come to a consensus agreement.  As a result, the upper and lower basin delegations each submitted separate proposals to the BoR in early March.
There is still a chance that both the upper and lower basin state groups can reach a common agreement for a unified proposal.  In the meantime, both proposals are under review by the BoR. Officials with the BoR have indicated that they will be working with the basin states in the next six months to develop a consensus draft proposal for post-2026 river management by the end of 2024.
Further details on the two proposals submitted on 6 March 2024 by the upper and lower basin groups and contrasting the two will be forthcoming in a future article.
For the excellent program that was provided at the 2024 SWAS, I want to thank Elston, Bart, and Hank for their outstanding presentations.  Each of the participants in this program brought a wealth of knowledge and experience to the discussion.  
Specifically for Bart and Hank, we are all indebted to them for their contributions and hard work while serving on the lower basin state delegations during these critical and challenging negotiations.  Their firsthand perspectives and contributions to this program are very much appreciated.

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.

Our newly constructed self-propelled steam applicator is designed to inject steam into the soil and raise soil temperatures to levels sufficient to kill weed seed and soilborne pathogens (140°F for > 20 minutes). After the soil cools (< ½ day), the crop is planted into the disinfested soil. We have done some preliminary testing and are very encouraged. Results show that the machine is able to reach target temperatures at reasonable travel speeds, provide uniform temperature distribution across the bed and form nicely shaped beds suitable for subsequent planting. We still have some bugs to work out and identified improvements to make before shipping the unit to Salinas, CA where we will conduct field trials with crops this summer. If you are interested in seeing the machine operate or more information about soil steaming for soilborne pest control, please feel free to contact me.
Check out a video of the machine operating by clicking here or on the image below.

Fig. 1. Initial testing of self-propelled steam applicator video.

Acknowledgements
This project is sponsored and funded in part by the Propane Education and Research Council (PERC), Arizona Specialty Crop Block Grant Program and USDA-NIFA. We greatly appreciate their support.

In our last newsletter we talked about the importance of proper weed identification before making decisions on control measures. We mentioned some of the literature that the Vegetable IPM Team uses at the Yuma Agricultural Center.
An increasing number of PCAs and growers are using several phone applications for weed ID.
In this update I would like to share some data that was collected from a group of students of the 2024 PLS 300 Applied Weed Science class.
Professor Barry Tickes asked his students to download two phone applications and test the accuracy of the weed species ID. The recommended applications used were PlantNet and PictureThis Plant Identifier, which according to some  Pest Control Advisors are reasonably accurate.
We provided a display of 9 weeds to the students to take images and upload to the phone apps for ID and here are the results obtained:
 
Weed                                         PictureThis                  PlantNet
 
Annual bluegrass                            6                                        0
 
Creeping woodsorrel                      8                                        6
 
Nettleleaf goosefoot                       4                                        3
 
Prickly lettuce                                 8                                        0
 
Spiny sowthistle                              6                                        1
 
Spinach                                            8                                        6
 
Malva                                              6                                         1 
 
Silversheath knotweed                    5                                         0  
 
Littleseed canarygrass                     0                                         0        
 
       PictureThis Plant Identifier performed better than PlantNet in this evaluation. Interestingly in 2022 the weed science class evaluated PlantNet with results showing that 84.6 % of the time the application was correct. If you have another application that you recommend, please send it in your comments and we will share it with others in this newsletter.   

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

Results of pheromone and sticky trap catches can be viewed here.

Corn earworm: CEW moth counts down in most over the last month, but increased activity in Wellton and Tacna in the past week; above average for this time of season.

Beet armyworm: Moth trap counts increased in most areas, above average for this time of the year.

Cabbage looper: Moths remain in all traps in the past 2 weeks, and average for this time of the season.

Diamondback moth: Adults decreased to all locations but still remain active in Wellton and the N. Yuma Valley. Overall, below average for January.

Whitefly: Adult movement remains low in all areas, consistent with previous years.

Thrips: Thrips adults movement decreased in past 2 weeks, overall activity below average for January.

Aphids: Winged aphids are still actively moving, but lower in most areas. About average for January.  

Leafminers: Adult activity down in most locations, below average for this time of season.