For the past 12 years, the UA Vegetable IPM Team has annually surveyed PCAs and growers to document insect pest activity, economic costs of insect management and insecticide usage in Arizona lettuce through interactive workshops held each April. The information collected during these workshops can be very useful to the lettuce industry by providing “real world" information on insect pest status and insecticides usage that can be used for addressing state and federal regulatory issues, prioritize research and educational activities, and translate the PCA’s activities into economic terms for their growers. In a recent VegIPM update (Jun 8), we discussed interesting trends in insecticide usage on desert lettuce based on the results of these workshops that can be found at Insecticide Usage on Desert Lettuce. Just recently we summarized the remaining data collected in the workshop surveys. Summarized over the past twelve-years (2004-2016), the survey data provides “real world” information on the pest status of key insect species, economics of insect management, and estimates of yield losses in lettuce. A quick analysis of the summary clearly indicates that insect management in desert lettuce is very intensive, can be expensive and is generally effective. Specifically, surveys completed by PCAs represented a large proportion of the lettuce acres grown in the Yuma, and neighboring Bard/Winterhaven growing areas. Not surprising, the surveys showed that annually 100% of the acres are scouted for desert lettuce pests and lettuce fields are visited >4 times per week. In terms of pest status, the Lepidoptera larvae complex (beet armyworm/ cabbage looper/corn earworm), western flower thrips, aphids and seedling, soil pests represent the most economically important insects attacking desert lettuce crops based on the % of treated acres, numbers of spray applications, and yield losses associated with each pest. In terms of yield losses, average estimated loss from any one pest never exceeded 1% in either fall or spring lettuce. Given the heavy insect pressure we experience each season, PCAs and growers should be commended on their capability of maintaining insect losses to such low levels over a 12-year period. However, it is important to note that this was accomplished in part, by the considerable expense and time invested by PCAs in scouting for these pests, and certainly by the significant investment in insecticide spray and application costs used each season to prevent these key pests from causing economic damage to lettuce crops. Bottom line: IPM in desert lettuce crops is effective, but at a cost. For a copy of the complete, summarized report go to: Insect Losses and Management on Desert Lettuce: 2004-2016.

The continuous development, testing, and incorporation of technology in agriculture is amazing.  I recently attended a western agricultural conference and when visiting the industry displays and booths, I was impressed with the new technologies that are coming into the agricultural arena.
 
Technological devices are tools and like all other tools, they are put to their best use in the hands of skilled craftsmen.
 
We have many excellent examples of technological tools in the crop production systems of the desert Southwest.  A basic example comes from the equipment used to till the fields, prepare a good seedbed, and then to plant a new crop by seed or transplant.  Excellent articles are provided in this newsletter on this topic regularly.  We tend to take this kind of equipment for granted until you must do the job by hand or with older technology.
 
Any new technology needs to be fully tested and demonstrated before anyone can expect it to be appropriately implemented.  That involves communicating the background, purpose, and utility of any new technology.  The cost/benefit ratios need to be worked out and presented.  A critical step in implementation is demonstration and establishing prima facie evidence to support the value of the new technology.  Testimonials are nice but there needs to be solid evidence to support claims of merit.  In science ideas demand testing and the presentation of proof.
 
A lot of emphasis recently has been placed on the technology and new tools available for soil-plant-water management and irrigation management.  There is a tendency for some people to think that our problems can all be solved with crop water management if we would just use the right technology.  In my view, some of the new irrigation technology is great and it can potentially be very useful in managing crop irrigation in the field.  But technology itself is not a panacea.
 
Despite the technological advancements that we do use and benefit from, the best potential improvements are dependent upon the skill and expertise of the farmers or field managers involved.  The skill set required to plant a crop, get a good stand, manage it to the proper level of maturity, harvest the crop, and then get it to market is indispensable and the responsibility comes down to individual farmers and farmer managers.  
 
The successful management of irrigation technology is totally dependent on the skill of the operator to make a personal assessment of a broad array of factors.  These factors include a review and assessment of the field in terms of crop condition and stage of growth, the soil moisture levels in relation to field capacity of the soil, the crop-specific irrigation requirements, allocating the appropriate amount of irrigation water needed, and the optimum time of application.
 
The ability of the farmer and/or farm manager to evaluate soils in the field regarding texture, water holding capacity, and current soil-water levels is essential.  Simple methods such as using a soil probe and estimating soil-water levels by feel with their hands remains and will continue to be a critical skill for farmers and field managers.  
 
I believe this is particularly true if one is trying to employ new technologies for irrigation management.  A good farmer can tell if the tools and technologies being employed are working properly.  They are the ones that usually take new tools to levels of use above and beyond what the developers were able to envision.
 
We all need a baseline in relation to crop-water management and the fundamentals will continue to be an important part of a farm manager’s skill set.  The new technologies may serve as good tools, but they will not replace the capacity of a farm manager to go into the field and figure out what is going on, put the tools or technologies to work appropriately, and not only apply them but do it well.  
 
Fundamentals are important, and they always will be.  This illustrates the fact that skilled professionals are essential in crop production. 

https://www.aglaw.us/agtech

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.

Interested in the latest developments in automated weeding machines? There are a couple of opportunities at the upcoming 2024 Southwest Ag Summit to stay up to date. One is the “Ag Tech: Innovations in Weed Control Technologies” breakout session where university experts and cutting-edge innovators will provide updates on the latest advances in AI, laser weeding, high precision smart spot sprayers, robotic/automated weeders and band steam (agenda below). The session will be held Thursday, February 22^nd  from 1:30-3:30 pm at Arizona Western College (AWC) in Yuma, AZ.
The other is the Southwest Ag Summit Field Demo on February 21^st, where several of these technologies and other state-of-the-art automated weeders will be demonstrated operating in the field. The Field Demos will also be held at AWC. Breakfast will be served at 7:00 am and demonstrations begin at 8:00 am.
For more information about the Southwest Ag Summit, visit https://yumafreshveg.com/southwest-ag-summit/.

Fig. 1. Agenda for the “Ag Tech: Innovations in Weed Control Technologies”
educational session at the 2024 Southwest Ag Summit. The session will be held
Thursday, February 22nd at Arizona Western College, Yuma, AZ.


Fig. 2. 2024 Southwest Ag Summit Field Demo agenda. The event will be held at
Arizona Western College in Yuma, AZ.

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.

Area wide Insect Trapping Network   VegIPM Update, Vol. 15, No. 3, Feb 7, 2024
 
Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:             
CEW moth counts increased in the Rol and Dome Vallley areas, above average for this time of year. 
 
Beet armyworm:         
Trap counts low; lower than average compared to previous years.
 
Cabbage looper:           
Cabbage looper counts increased in most traps and about average for this time of season.
 
Diamondback moth:       
DBM moths counts increased in most areas. About average for this time of the year.
 
Whitefly:                       
Adult movement negligible, typical for mid-winter. 
 
Thrips:                          
Thrips adult counts remain low, likely in response to rainfall in late December. Currently, numbers are below average compared with previous years.
 
Aphids:                        
Aphid movement increased significantly in the past two weeks, particularly in North Yuma and Gila Valleys. Highest numbers we’ve seen in 11 years.
 
Leafminers:                   
Adults remain low in most locations, average for January.