Worm pressure has been picking up in some areas, but lighter than what we experienced this time last year.  Beet armyworms are showing up on early lettuce about 8 days or so after wet date, but overall, armyworm pressure appears to be lighter than what we normally see this early in the season. This is also reflected in our pheromone traps where moth captures have been lower than average so far for September. Cabbage looper moth activity has been lower than average as well. A few reports of diamondback moth larva showing up in transplanted and direct-seeded brassica crops but nothing to get excited about. We even had one report of cabbage budworm showing up on organic cauliflower in Tacna. Regardless, it’s late September and you know worms will continue to show up on young stands, particularly if the weather stays warm.  Average temperatures over the next 14 days are forecasted to be around 85°F; that’s ideal for Lep larval development, oviposition, and reproduction. Remember, temperatures drive larval development and adult moth oviposition, particularly when nighttime temps stay warm (in the 70s). The moths are nocturnal and will actively oviposit when evenings are warm, and winds are light.  If average temperatures remain around 80-85°F, worms will be active at damaging levels. So, keep an eye on the weather forecast as the season progresses, especially the nighttime temperatures. 
 
Fortunately, there are several effective insecticides that can be applied as stand-alone foliar products that provide effective residual control of these lepidopterous species. Radiant, Proclaim, Intrepid, Avaunt and the Diamides (Coragen, Exirel, Besiege, Minecto Pro, Harvanta) can provide good knockdown and extended residual control of beet armyworms and cabbage loopers.  That’s five effective modes of action to rotate with. Addition of a pyrethroid can enhance knockdown of corn earworm and cabbage looper for many of the products (i.e., Intrepid, Proclaim), as well as provide moth suppression. 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 plant size at time of application and how fast the plant is growing. Before selecting a product for worm control, be conscious of chemistries previously used on the crop. If your grower has applied a diamide soil treatment at planting (i.e, Coragen, Verimark), use another chemistry to control worms once the soil residual has played out, usually around 30 days after wet date. For resistance management purposes, avoid using a foliar diamide product on crops treated with a soil applied diamide at direct-seeding or transplant for a least 60 days.  Also, when practicable 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 Lep larvae can be found in this documents:   Lepidopterous Larvae Management in Desert Produce Crops, 2023

The drought-related pressures on the Colorado River system that have been impacting the entire basin and region for 23 years have slackened briefly due to the wet winter in 2023 that included a good snowpack in the mountains, better rainfall throughout the basin, and improved flows into the river.  The current water level at Lake Mead on Hoover Dam is 1,068.25 ft. above sea level on 3 January 2024.  That level is 160.75 ft below full pool of 1,229.00 ft. (Figure 1).

 

In mid-December 2023 representatives from each of the seven Colorado River Basin states met in Las Vegas, NV during the annual Colorado River Water Users Association conference.  The focus of current discussions among the basin states is 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.  The immediate goal is to draft proposals by March 2024.
 
The negotiations are incentivized by having the opportunity for the post-2026 guidelines being developed by the basin states themselves as opposed to litigation or legislation.  A major concern driving this process among the basin states that basin state representatives should be able to do this better than turning the process over to people and entities that have less direct familiarity with the situation and no real “skin” in the game.  
 
The 1963 decision by the Supreme Court of the United States in of the Arizona v California case directed the federal authority on the management of the Colorado River to the Department of the Interior and the Bureau of Reclamation (BoR).  However, the basin states have the chance to negotiate their future management plans on the Colorado River.  If they fail to do so in the allotted time, the process will be managed by the federal government.  
 
The basic water budget challenge is based on the following basic statistics:
 

• The current water budget on Colorado River allocations is 16.5 million acre-feet (maf)/year.
• Average annual flow on the Colorado River from 1906-2017 was 14.8maf/year.
• The average annual flow between the years 2000 - 2018 has been approximately 12.4maf/year.
• That is 16% lower than the 20^th century average flow.
• It is estimated that 1.5 maf/year is lost due to evaporation and system loss.
• Thus, the 4 maf/year target reduction that has been identified by the BoR is basically the difference between the 16.5 maf/year allocated versus the 12.4 maf/year average flow in the first two decades of this century.

 
Some notable progress is being made for conservation of Colorado River water with agreements among lower basin states and tribes that will conserve more than 1.5maf/year through 2026.  For example, California water agencies have recently agreed to conserve up to 643,000 acre-feet/year through 2025.  The Quechan Indian Tribe has reached an agreement with federal water managers to save up to 39,000 acre-feet/year through 2025.  Arizona has agreed to conserve up to 348.00 acre-feet/year through 2026.  All these temporary agreements are being supported with federal funding.
 
With agriculture responsible for 70% of the diversions on the Colorado River, these negotiations are extremely important for the future of agriculture in this region and our capacity to support high population densities that are now common and rapidly growing.
 
These types of negotiations are certainly challenging in dealing with a limited water supply and a lot of demand.  There are many competing interests involved.  Yet, we are confident that the representatives we have will be able to work this out and come to a set of functional agreements.

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.

Time flies. February is right around the corner and that means it is farm equipment/ag trade show season. Upcoming regional events include the World Ag Expo, Tulare, CA, February 13-15, the Southwest Ag Summit, Yuma, AZ, February 20-22, and AgroBaja, Mexicali, Mexico, March 7-10.  If you are interested in the latest ag tech and farm machinery, all are outstanding events and well worth attending. For more information, click on the links below.

Fig. 1. Upcoming farm equipment/ag trade show events: World Ag Expo, Tulare,
CA, February 13-15, 2024 theSouthwest Ag Summit, Yuma, AZ, February 20-
22,2024 and AgroBaja, Mexicali, Mexico, March 7-10, 2024.

Before making decisions for weed control it’s imperative to have a proper identification of the plant species. There are two names for plants:
The common name, which is a name that people come up with in a certain region to describe a particular weed and it varies by region and therefore can be confusing. Then we have an exact scientific name for each species that is based in the binomial nomenclature system started by Carl Linnaeus in 1753. This binomial (or two term) system includes the genus and the species, which is used worldwide¹.
 
Some very close species from the same family can be controlled by the same product but occasionally their herbicidal susceptibility varies. Such is the case of Chenopodium murale (goosefoot) and Chenopodium album (lambsquarter) two very close and similar species. A product like Pursuit (Imazethapyr) has good activity on goosefoot but can’t control lambsquarters. With accurate identification in a mixed population, you would be able to determine what strategy to use or select the herbicide that would control both species. 
 
There are about 75 weeds most common in Arizona and are included in the PCA² study guide, but many other species could be introduced to the State and complicate our crop production systems. Two great tools for weed identification are the books “An Illustrated Guide to Arizona Weeds” that lists 172 species, and “Weeds of California and Other Western States” which has at least one photograph of 735 weeds.
Another weed identification tool is the book “Weeds of the West”.
Additionally, there are many phone applications that can be used as identification tools such as “id weeds”, “PlantNet”, “PictureThis”, “iNaturalist”, “Seek”, “PlantSnap” and “LeafSnap”. When we have problems with weed ID we contact the UA herbarium.
Thank you for sending samples for Weed ID to the IPM Team it is always a learning experience.

 Area wide Insect Trapping Network   VegIPM Update, Vol. 14, No. 1, Jan 11, 2023
 
Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:             
CEW moth counts are down areawide average for this time of year. 
 
Beet armyworm:         
Trap counts increased in most ll locations; about 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 continue to increase in all areas. About average for this time of the year.
 
Whitefly:                       
Adult movement light and is typical for this time of year. 
 
Thrips:                          
Thrips adult counts beginning to slowly increase in the past 2 weeks. Currently, below average compared with previous years.
 
Aphids:                        
Aphid movement increased significantly in North Yuma and Gila Valleys consistent with winds and storms. About average for early January.
 
Leafminers:                   
Adult activity up in many locations, and above average for January.