Desert growers have begun planting fall melons and transplanting cole crops, while direct seeding of produce crops is just a couple of week away. Accordingly, PCAs and growers will soon be faced with a number of important insect management issues. As crops begin to emerge, they can expect to encounter a number of insect pests that have the potential to cause serious economic losses to crop stands. These include flea beetles, crickets (sometimes grasshoppers), darkling and rove beetles, and saltmarsh caterpillars (‘woolly worms’). These insects all have chewing mouthparts and most are capable of consuming large amounts of leaf tissue in a short period of time. Seedling crops at the cotyledon stage are most susceptible; these pests can devour entire cotyledons or outright kill small seedlings. If left unprotected, larger seedling plants (1-2 leaf stage) can sustain significant feeding damage on the terminal growing points or newly emerged leaves. Not only can this feeding stunt plant growth, but can result in lack of stand uniformity and ultimately, maturity at harvest. Host crop sources of flea beetle, cricket and "woolly worm" infestations include numerous summer crops (e.g., sudan grass, cotton and alfalfa) and weeds (e.g., purslane). We are currently noticing high numbers of flea beetles and crickets at the Yuma Ag Center on sudan grass and weeds. Salt caterpillars have not been detected, but are known to disperse from alfalfa and pima cotton. Experience indicates that melon fields planted adjacent to these crops/weedy areas are at a high risk from these seedling pests, particularly flea beetles. As summer crops are harvested or terminated during the next several weeks, these seedling pests typically move to the next available host crop; lettuce, cole crops and melons. Fortunately, there are many registered insecticide alternatives available that can be applied via sprinkler chemigation (i.e., pyrethroids) or foliar sprays (i.e., methomyl, neonicotinoids) that can cost-effectively minimize their abundance and damage to emerging produce and melon crops. Additionally, seed treatments are available for lettuce and cole crops that will protect stands from flea beetles. For more information on insect pests of leafy vegetables and melons at stand establishment please see Insect Management on Desert Produce and Melons: Pests at Stand Establishment.

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%). 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.

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.

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

Corn earworm: CEW moth counts down in most traps over the last week; about average for early October.

Beet armyworm: Trap counts increased in several areas last week, and about average for early October.

Cabbage looper: Cabbage looper trap counts increased in most locations, but still below average for this time of the season.

Diamondback moth: Adult activity spiked 2 weeks ago, particularly in the Yuma and Dome Valleys, but down over the past week. Average for this time of season.

Whitefly: Adult movement increasing Tacna consistent with melon harvests; overall about average for early October.

Thrips: Thrips adult movement peaked 2 weeks ago but down ovr the past week, overall activity above average.

Aphids: Winged aphids beginning to show up the north Yuma and Gila Valleys; below average for October.

Leafminers: Adult activity increased significantly last week in several locations, above average for this time of season.