Historically, beet armyworm and cabbage looper are the most important pests of produce during September and October based on our annual Lettuce Insect Losses surveys. Now with produce planting well underway, it is no surprise that worms are beginning to show up in fields that have been in the ground for 10 days or more. Here at the Yuma Ag Center, one can easily find new egg masses and neonate beet armyworm larvae on 10-11 day old lettuce and broccoli stands; and in fairly high numbers. Samples taken from our experimental field plots showed that about 10% of 1-leaf stage lettuce plants examined had larvae and/or damage. This is well above threshold. Similarly, cabbage loopers were fairly abundant on our fall melons this year, but so far none have been observed on produce yet. It is still a little early for looper, but they are right around the corner. Remember, temperatures drive larval development and adult activity, particularly when night time temps remain high (in the mid-70s or higher). The higher temperatures we’ve been experiencing the past week or so are ideal for worm development and moth activity. As long as the average temperature remains around 85°F, worms should be active at damaging levels. Fortunately, there are a number of very effective insecticides that can be applied as stand-alone foliar products that provide effective residual control of both of these lepidopterous species. Radiant, Proclaim, Intrepid, Avaunt and any one of the Diamide products (Coragen, Belt, Voliam Xpress and Vetica) can provide good knockdown and extended residual control of armyworms and loopers. Over the past few years, our research trials have demonstrated that these products provide comparable control on lettuce and cole crops. Of course, residual control will often depend on the rate applied. In general, the higher the rate, the longer the residual, but this will also depend on how fast the plant is growing and plant size. Before selecting a product for Lep control, be conscious of products (chemistries) previously used on the crop. Avoid using products with the same mode of action more than twice on any given field. More information on the insecticides available for effective control of beet armyworm and cabbage looper can be found in this document: Lepidopterous Larvae Management in Desert Produce Crops 2013.

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.

We did some trials at the University of Arizona Yuma Agricultural Center in broccoli to evaluate and compare Napropamide (Devrinol) liquid formulation 2XT versus the Dry formulation DF-XT. 
This product inhibits the production of fatty acids in plants, which is crucial for plant development. It affects primarily the meristematic cells which are in growing points of the stems and roots. We saw activity especially on seedling development that we show in some pictures at the end of the article. 
Some growers expressed their concern on the safety of different levels of incorporation with sprinkler irrigation. Therefore, we established a test in which we applied the product as a broadcast application after planting. Then we used different levels of incorporation in some sections using 12, 24 and 36 hours of sprinkler irrigation. No difference was observed with the incorporation level in our trial. We observed temporary phytotoxicity from 4-10%. The data was obtained from visual evaluations. Also, a 0.5 to 1” height reduction was exhibited when compared to untreated plots. 
It is common that growers and PCAs make management decisions on herbicide applications in different crops knowing that some injury is expected. Such is the case for alfalfa, wheat, spinach, lettuce and in this case broccoli. Frequently slight stunting it is not noticed because commercial fields don’t have untreated areas for comparison.
We talked to PCA’s and growers at the SW Ag Summit and asked for their experience with napropamide this past season. Some noticed the broccoli exhibited similar levels of phyto, which they considered economically tolerable. 
We noticed that good soil prep was important for before the application of the product and avoiding direct contact of the seed with the product for best results.
On weed control we noticed good activity on nettleleaf goosefoot and lambsquarter. 
At the 45day we collected data counting SMALL and LARGE weeds and at the 60 day evaluation we noticed most of the SMALL goosefoot and lambsquarter in the high rate of napropamide plots stayed small (pic. below).

Area wide Insect Trapping Network   VegIPM Update, Vol. 11, No. 22, October 28, 2020

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

Corn earworm: Moth activity is about average for mid-October, particularly in Dome Valley and south Yuma Valley. 

Beet armyworm: Moths remain active throughout the desert, especially active in Tacna and Dome Valley.

Cabbage looper: Cabbage looper activity remains unusually low for early October, likely a result of unusually hot weather. Larvae are yet to show up in many fields.   

Whitefly: Adult movement has been about average for this time of year. Activity highest in Tacna near fall melons.

Thrips: To date, thrips activity has been seasonably low at all trap locations; activity increased significantly in Roll. 

Aphids: Aphids beginning to show in most traps along the Colorado River (Bard, Gila, Yuma) which is normal for this time of year.  Recent high winds may begin to disperse them throughout the area.

Leafminers: Adult activity below normal for September, but high numbers caught in Wellton in areas where melon harvest has commenced.