At a recent meeting, I made the statement that the insect pest pressure on produce and melons crops in the Yuma area this fall was as heavy as I’ve seen it in many years. That comment was based largely on my observations, both on and off the Yuma Ag Center, as well as from anecdotal reports from PCAs and growers. This claim is further supported by a quick analysis of both recent and historic data on pest abundance recorded from our research plots here in the Yuma area. First, whitefly adult numbers on fall melons and produce were extremely high. In fact, my untreated melons plots on the Ag Center wilted and died rapidly as a direct result of heavy whitefly feeding. Furthermore, captures of whiteflies on yellow sticky traps placed near cantaloupe fields in the Wellton, Tacna Texas Hill area, were twice as high as they have been in the past 5 years, and CYSDV incidence in cantaloupe fields in this area was also higher in 2012. Similarly, worm pressure - particularly beet armyworm and cabbage looper- was higher than I’ve seen it in the past 6-7 years. Populations began infesting plots in early September, and egg deposition and larval development remained steady through October. In fact, worm numbers were 3-fold higher in 2012 than we what observed last fall. Additionally, corn earworm was present in higher numbers than what I’ve observed in past years. Finally, Bagrada bug infestations were the highest I’ve seen on the Ag Center since the invasive stinkbug first showed up in Yuma in 2009. The low-moderate population appeared in early September, but reached very high levels by mid-September and peaking in early October. The numbers I observed were much higher than the populations that occurred last season, and actually slightly higher than we saw in 2010. The infestation levels in our untreated broccoli plots this year remained at damaging levels throughout October. In contrast, thrips population numbers have been low, relative to what we normally see this time of the year, and I have not picked up any winged aphids or colonies on lettuce thus far. However, I’m not sure how that translates to potential population pressure in January and February, and you should anticipate them showing up as usual. I’ve been asked why the pest pressure was so relatively heavy this year. I really don’t know. Could the heavy monsoon moisture we had in July and August have been an influence? It may have, but it may not have. Insect abundance is dictated by many abiotic and biotic factors in our cropping system, and it’s nearly impossible to consider all the factors necessary to draw a reliable conclusion. Nonetheless, graphics showing these recent trends in Whitefly, CYSDV, Lep Larvae and Bagrada abundance can be found at Pest Abundance on Desert Produce and Melon Cops in 2012.

John Wesley Powell, the Civil War veteran who lost most of his right arm at the Battle of Shiloh, led his first expedition down the Green and Colorado Rivers, including the Grand Canyon in 1869.  This provided the first exploration of the Colorado River basin by Americans of European descent and it began the process of understanding the nature of western territories of the United States, including Arizona (Figure 1).
 
The degree of aridity of this region was very strongly impressed upon Powell and he spent much of his life working to educate law and policy makers of the conditions prevalent in the western U.S.  He worked diligently with lawmakers, government experts, and citizens to communicate the fact that the development of the western territories, which the nation was rapidly embarking on after the Civil War, would be limited due to the lack of water.  His comments to the Montana Constitutional Convention in 1889 “All the great values of this territory have ultimately to be measured to you in acre feet” is a good example of his basic message and it has proven to be quite prophetic in our experiences of living and working in the desert Southwest in the 20^th and 21st centuries.
 
Powell became the second director of the U.S. Geological Survey (USGS) from 1881 to 1894.  In this and similar capacities, he constantly advocated for policies for the development of the arid West that were consistent with the prevailing arid conditions.  As the lands in the western U.S. were being developed, the need for land “reclamation” was recognized.  It was 120 years ago this week, on 17 June 1902 that Theodore Roosevelt signed the Reclamation Act and the U.S. Reclamation Service (USRS) was formed within the USGS under the Secretary of the Interior Ethan Allen Hitchcock.  The new USRS was given the responsibility of studying potential water development projects in each western state with federal lands.  Revenue from the sale of federal lands was the initial source of the USRS funding.
 
Thus began the process of the USRS in the development of about 30 western water projects between 1902 to 1907.  In 1907, the Secretary of the Interior separated the USRS from the USGS and created the Bureau of Reclamation (BoR) as a distinct entity within the Department of the Interior.  The Boulder Canyon (Hoover Dam) project was authorized in Congress in 1928 and funded by general funds appropriated by Congress to the BoR, and from that the development of Lake Mead began.  Lake Mead is the main storage reservoir for the lower basin of the Colorado River.
 
In the late 19^th and early 20^th centuries, efforts in the western U.S. to develop lands for agriculture encountered problems with lands and soils that were found to be unsuitable for irrigation, often due to salinity, sodicity, and drainage problems.  The “reclamation” of these lands became an important part of the BoR objectives and operations.  All this development was dependent on the availability of water and good land and water management capacities.
 
During the 20^th century, the BoR was responsible for some tremendously large and ambitious projects, including Boulder Dam, Grand Coulee Dam, Glen Canyon Dam, and many others.  Today, the BoR operates in 17 western states with water and electrical power projects with more than 600 dams, reservoirs, powerplants, and canals.  The BoR is the largest wholesaler of water in the U.S. and supports irrigation water storage and conveyance throughout the west on farmlands that produce more than 60% of the nation’s vegetables and 25% of the fruit and nut production in the country. The BoR is the second largest producer of hydroelectric power in the U.S. with 53 powerplants.  The western U.S. development and population is heavily dependent on the BoR water and power works.
 
In Arizona and the desert Southwest, the lands and people here today have a very close relationship to the BoR for water and electrical power.  All the lands along the mainstem of the Colorado River and the Central Arizona Project (CAP) are intimately connected to the BoR.  Our efforts to deal with the water shortages on the entire Colorado River system are some of the greatest challenges this region and the BoR have faced since the early days of development in the 19^th century.  
 
Thus, there are many participants in the process of dealing with the current water shortage on the Colorado River system, including the U.S. Department of the Interior, the BoR, and all the basin states.  An accentuating feature of the current water shortage on the Colorado River is due to the fact that for the past 22 years, the average annual flow in the Colorado River has been ~ 12.4 million acre-feet (maf) while the Colorado River water is budgeted for a total of 16.5 maf of allocations between U.S. states and Mexico. 
 
Essentially, all of us living in the desert Southwest are in this together; including agricultural, urban, and tribal entities.  All parties involved must work together to resolve this disparity between the water that the river is providing and the greater amount that is desired and allocated.  The issues and general situation that we are facing has an urgency that requires immediate attention.  I remain hopeful that we can meet the challenges of our time as our predecessors did in the past.

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%). Lettuce was seeded, then sprinkler-irrigated to germinate seed on Nov 28, 2023 on double rows 12 in. apart on beds with 42 in. 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, which contained two 25 ft rows of lettuce. Plants were thinned Jan 17, 2024  at the 3-4 leaf stage to a 12-inch spacing. 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.

Month	Max Temp (°F)	Min Temp (°F)	Average Temp (°F)	Rainfall
November	80	51	65	0.08 in
December	71	44	57	0.82 in
January	68	42	54	1.14 in
February	73	47	59	0.50 in

 
Powdery mildew (caused by Golovinomyces cichoracearum) efficacy trial treatments were made on February 15,2024, February 23, 2024, March 4, 2024, and March 12, 2024and .Disease was first seen on February  26,2024. Disease rating was done on March 15, 2024.   Disease severity was determined  by rating 10 plants within each of the four replicate plots per treatment using the following rating system: 0 = no powdery mildew present; 0.5 = one to a few very small powdery mildew colonies on bottom leaves; 1 = powdery mildew present on bottom leaves of plant; 2 = powdery mildew present on bottom leaves and lower wrapper leaves; 3 = powdery mildew present on bottom leaves and all wrapper leaves; 4 = powdery mildew present on bottom leaves, wrapper leaves, and cap leaf; 5 = powdery mildew present on entire plant. These ratings were transformed to percentage of leaves infected values before being statistically analyzed. Yield loss due to rejected lettuce heads would likely begin to occur on plants with a powdery mildew rating above 2.0 (percentage of leaves infected value of 40).         
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. The most effective fungicides were Rhyme, Merivon, Quintec, Cevya, Luna Sensation, Luna Experience, and Elisys. 

Interested in staying up to date on the latest international robotic ag technologies? FIRA (International Forum for Agricultural Robotics) held an “Open Day” May 13th and posted recorded presentations on their website. In addition to technical panel discussions with industry experts, the event included live field demos of weeding, scouting and general farming robots. The FIRA Connect website also has replays of presentations given at the 2021 FIRA Conference held last December. In total, there are thirty short presentations and field demos of ag robots freely available. About 1/3^rd of the presentations/demos are weeding machines from Europe that utilize various methods for in-row weed removal – lasers, precision spot sprayers, concentrated light beams, and mechanical devices including knife blades, rotating heads, and weed pulling mechanisms. The site also provides links to a “Robot Wall” and a “R&D Wall” where companies have posted information about their commercially available and in-development ag robots. It is a quality website and worth checking out to learn more about the latest automated agricultural technology innovations being developed around the world. 

To connect to the FIRA website, click here

Overreliance in glyphosate could increase the risk of reduced efficacy of this herbicide. Some the weeds difficult to control with glyphosate in our area are: Hairy fleabane (Coniza bonariensis), Horseweed (Coniza canadiensis), White sweet clover (Melilotus albus). Pig weed (Amaranthus palmeri), and Cheeseweed (Malva parviflora). We are conducting experiments in the Yuma area to identify effective herbicide control options for Hairy fleabane. Some research done in Australia has shown that Fleabane cannot be controlled with a single herbicide treatment even with knockdown herbicides such as paraquat + diquat, and researchers suggest the need of combinations of different modes of action to achieve control effectively¹. In one fleabane evaluation started May 6, 2022, we included the following treatments: 1. Embed Extra 2pt/A+5%NIS 2. Rely 82 floz+5%NIS 3. Chateau+ Treevix+MSO (12oz+1oz/A+1%)

We noticed treatments including Glufosinate (Rely) showed best burndown activity, but regrowth was observed in two weeks (13-14 plants per ft²). So, a second application was performed on three weeks after first on the Rely plots.
The grower and PCA informs us that Sulfenacil (Sharpen) has worked effectively for them with sequential applications. Additionally, we are evaluating Suppress and Clopyralid in the same location.

You are always welcomed to send your comments, suggestions to the IPM Team. Let us know what you are doing and your findings. We know there is a researcher in every grower and PCA and your input is greatly appreciated.

1. Hanwen Wu, Steve Walker and Geoff Robinson (2008). Chemical control of flaxleaf fleaeabane (Conyza bonariensis (L.) Cronquist) in winter fallows. Plant Protection Quarterly Vol.23(4) 2008
2. Travlos, I., & Chachalis, D. (2010). Glyphosate-Resistant Hairy Fleabane (Conyza bonariensis) Is Reported in Greece. Weed Technology, 24(4), 569-573. doi:10.1614/WT-D-09-00080.1

Area wide Insect Trapping Network   VegIPM Update, Vol. 11, No. 21, October 14, 2020

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

Corn earworm: Moth activity is above normal for early October ad has been steadily increasing since mid-September, particularly in Dome Valley and south Yuma Valley. 

Beet armyworm: Moths remain active throughout the desert, especially in Texas Hill and Dome Valley growing areas.

Cabbage looper: Cabbage looper activity remains unusually low for early October, likely a result of unusually hot weather. Larvae just starting to show up in some fields.   

Whitefly: Adult movement has been about average for this time of year. Activity highest in Wellton and Roll near fall melons.

Thrips: To date, thrips activity has been seasonably low at all trap locations; most activity found in Bard.  Numbers beginning to slowly trend upward

Aphids: Aphids have been caught in only one trap thus far (Bard). Normal for this time of year.  Still early, anticipate they will begin to show up in heavier numbers in mid-late October.

Leafminers: Adult activity below normal for September, but moderate numbers caught in Wellton and south Gila Valley in areas where cotton was recently harvested and disked under.