Insect activity over the past week has started to pick up. We have seen a significant increase in green peach aphid pressure here at the Yuma Ag Center. Similarly, most PCAs I’ve visited with have noted similar increases in aphid activity and are keeping them under control. Although worm pressure has been light in the field for the past month or so, it would be wise to keep a keen eye out for corn earworm (CEW).   In the past, high CEW abundance has occurred on late head lettuce (March), particularly in the Dome/Wellton areas.  Surprisingly, our most recent trap catches showed significant moth flights in Roll, Dome Valley, and north Gila Valley following several weeks of inactivity (see graphs below). This is typical for February and could be the calm before the storm.  The last time we saw CEW moth activity this early (2015), we had reports of high numbers of CEW larvae in the field at harvest. These most recent trap counts should be used as an early indicator that moths are actively flying at night at higher abundance and PCAs should start to scout more aggressively for eggs and larvae.  You should be especially wary of CEW given the higher nighttime temperatures forecasted for the next 2 weeks. 
 
CEW can be very damaging in spring crops once head formation begins; larvae will usually bore into the head 1-2 days upon hatching.  Corn earworm is much more likely to bore into lettuce heads or romaine hearts than other Lepidoptera larvae, rendering the heads/hearts unmarketable.  If fields are not watched closely, infestations may not be noticed until harvest. Once inside the head/heart, control of larvae with currently available insecticides is not possible. Thus, pay careful attention for newly oviposited eggs (laid singly) on lettuce plants, particularly close to the base of the head. If you are beginning to find eggs and suspect that CEW are active in the field when plants are beginning to head, it would be a good idea to treat at regular spray intervals (~ 7 days). The UA nominal threshold for CEW in head lettuce from early heading to harvest is 1-2 larvae / 100 plants. Essentially, you find one larva, you spray.  Repeated insecticide treatments may be required to maintain low population levels near harvest.  Most contact insecticides recommended for Lepidopterous larvae are active against CEW. Furthermore, the addition of a pyrethroid with thrips, aphid and/or fungicide sprays may be cheap insurance against CEW larvae beginning to emerge as you approach harvest. For more information on CEW management and control recommendations see Corn Earworm Management on Desert Produce and the  2023 Lep Control Chart.

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%). 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.

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. 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.