Western flower thrips are now beginning to increase on produce crops throughout the area. This is evident from sample collected here at the Yuma Ag Center and by the increase in areawide trap catches (see Areawide Trap Insect Network). They have slowly been increasing in the Yuma Valley, and should likely continue to increase as the days grow longer. The recent rainfall we had last weekend may temporarily reduce numbers, but don’t expect that to last very long. Based on historical data, if temperatures remain moderate and rainfall is light we can expect thrips numbers to reach high levels by the mid-March and into April (see graph below). Another factor PCAs should be concerned with this time of the year is thrips "bioconcentration" which occurs each year in March as lettuce acreage declines. This could be especially important this season since the abnormally warm temperatures appear to be pushing lettuce harvests ahead of schedule relative to years past. Each time a lettuce field is harvested and disked, adult thrips populations disperse from these areas into the next available lettuce field. This is generally coincident with our seasonally warm temperatures that are suitable for thrips development. As the number of lettuce acres becomes reduced near the end of the season, this creates a bottleneck effect that concentrates high numbers of thrips adults on the remaining fields under production. This can often make chemical control very difficult, particularly in March, as thrips adults may continually re-infest fields following spray applications. Furthermore, by mid-March when most of the lettuce production is finished, these populations can pose a threat to seedling cotton. Note: the key to preventing thrips from significantly scarring leafy vegetable plants is to prevent immature populations from becoming established. For more information on the management of thrips on desert produce please see the Thrips Control Chart 2015. 

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 JV farms at Gila Valley. Lettuce variety ‘Guapo’ was seeded, then sprinkler-irrigated to germinate seed on September 19, 2023, on double rows 12 in. apart on beds with 42 in. between bed centers.  Rest of the irrigation 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, which contained two 25 ft rows of lettuce. Plants were thinned on October 9, 2023 at the 3-4 leaf stage to a 12-inch spacing. Treatment beds were separated by single nontreated beds. Treatments were applied by incorporating in soil before seeding or with a tractor-mounted boom sprayer that delivered 50 gal/acre at 100 psi to flat-fan nozzles spaced 12 in apart.

Month	Max	Min	Avg	Rain
September	100	71	86	0.71 in
October	93	61	77	0.00 in
November	80	51	65	0.08 in
December	71	44	57	0.82 in

 
Fusarium wilt (caused by Fusarium oxysporum f. sp. lactucae ) rating was done in the field by observing the typical symptom of lettuce wilt. Confirmation was done by cutting the cross section of roots. Disease scoring/rating was done on December 6, 2023. 
 
The data in the table illustrate the degree of disease control obtained by application of the various treatments in this trial. The disease pressure was extremely high in 2023, and most treatments showed little or no control against the disease. The treatments that showed some activity were Bexfond, Cevya, Rhyme, and Serifel. Plant vigor was normal and phytotoxicity symptoms were not observed in any treatments in this trial.

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 decrease to very low levels  in areas, about average for this time of year.
 
Beet armyworm:          
Trap counts low; increased slightly in the Yuma Valley; lower than average compared to previous years.
 
Cabbage looper:          
Cabbage looper counts deceased in most traps and below average for this time of season.
 
Diamondback moth:       
DBM moths counts increased Gila and Yuma Valley. About average for this time of the year.
 
Whitefly:                    
Adult movement negligible, average for late winter. 
 
Thrips:                         
Thrips adult counts remain low, likely in response to cumulative rainfall this winter. Currently, numbers are below average compared with previous years.
 
Aphids:                       
Aphid movement decreased significantly in the past two weeks; about average for mid-February
 
Leafminers:                   
Adults remain low in most locations, increased in Yuma Valley; average for mid February.