With the weather staying relatively warm so far this fall, insect pressure remains steady. This is indicated in part by our counts taken from in our trap network. Worms remain heavy in most areas, but whitefly flights are beginning to subside except in those areas out east near fall melons. However, as temperatures begin to cool down in the next few weeks, it is important that you not forget about Liriomyza leafminers, particularly as the first produce fields approach harvest. Leafminer numbers have been moderate thus far this season, but we have recently observed higher numbers (adults and larvae) showing up on the older leaves of lettuce here at the Yuma Ag Center. In addition, an increase in adult flies has been observed on yellow sticky traps used for monitoring whiteflies over the past week or so. In most cases, these traps have been located near or adjacent to fall melons, cotton or alfalfa. The 10-day forecast calls for temperatures to be in the 90s for the next week, and leafminer adults should continue to be active. Larval activity could easily cause damage if left uncontrolled in lettuce or baby leaf fields where they are currently present. These larvae can cause significant damage to older, pre-harvest lettuce by feeding and damaging wrapper leaves of head lettuce and romaine. Pupae collecting within the leaf margins can also be considered contaminants. In addition, baby leaf lettuces, spring mixes and spinach are susceptible to larval feeding (mining) on the tender growing leaves. These populations can be effectively controlled with currently available products. Products that are presently being used to control armyworms, loopers and thrips such as, Radiant (5-7 oz/ac), Coragen (5-7 oz/ac), Voliam Xpress (9 oz/ac), and Exirel (15-20 oz/ac) can effectively kill newly emerged larvae in the leaf mines before they cause significant damage. Be sure to include a penetrating adjuvant with these products to enhance translaminar movement of the product and larval control. For more information on leafminer biology and management please go to: Leafminer Management.

Everything we eat and much of what we are surrounded by in our daily lives have a common base from water and the production of green plants.  Anything made of carbon, even if the immediate source of carbon is a petroleum-based product, has an original derivation that starts with green plants and water. 
 
Green plants perform the miraculous process of photosynthesis that captures light energy from the sun to combine with water (H₂O) taken up from the soil through the root system, carbon dioxide (CO₂) from the air, forming a simple 6-carbon carbohydrate compound (C₆H₁₂O₆), and liberating free oxygen (O₂) into the atmosphere. 
 
Photosynthesis involves a complex system of biochemical reactions, but the fundamental photosynthesis process can be reduced to very simple terms as outlined in Figure 1.

Figure 1.  Basic photosynthesis reaction.  (Source: Collegedunia).

Figure 2 offers a little more detail in the photosynthetic process and there is still more to the story.  But the essentials are outlined in Figures 1 and 2.

Figure 2.  Connections between photosynthesis and plant respiration.

The process of taking CO₂ from the atmosphere and “fixing” the carbon in a larger and more complex form as a basic carbohydrate (simple sugar compound) is referred to as “carbon fixation” and green plants provide most of this primary function in the earth terrestrial, or land-based ecosystems.  
 
Carbon fixation is conducted by organisms containing chlorophyll and green plants do most of this work.  There are also some species of algae and cyanobacteria that can fix carbon from the atmosphere.  But green plants, using energy from the water and water from the soil are the real workers in our world in this regard.
 
Water is essential in this process of fixing carbon through photosynthesis.  In fact, six units of water are required for every unit of carbohydrate that is produced (Figure 1).  
 
Additional water is used by the plant in the transpiration process, which is the movement of water from the soil through the root system, through the conductive tissues of the plant.  This provides for good cellular hydration and biological function.  In the transpiration process water moves out of the plant and escapes into the atmosphere as gas through the stomates, which are small openings in the underside of plant leaves (Figure 3).

Figure 3.  Plant transpiration.  Source: Premium Vector

Through this process of photosynthesis, water and green plants serve as the backbone of all terrestrial life.  These are fundamental facts and critical functions that we manage in crop production systems.  Essentially, every field with a green crop growing is a photosynthetic factory and water is always an essential component.  
 
Consumers directly benefit from the water used to produce the crops with all the fruits and vegetables that come from them.  Healthy animals require good food, which all comes from plants, i.e., alfalfa.  Everything we consume has a significant water footprint and much of that involves supporting plant photosynthesis.
 
The inescapable fact is that we need the plants, and the plants need water to grow and produce.

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%). Spinach ‘Revere’ was seeded, then sprinkler-irrigated to germinate seed Jan 18, 2024 on beds with 84 in. between bed centers and containing 30 lines of seed per bed.  All irrigation water was supplied by sprinkler irrigation.  Treatments were replicated four times in a randomized complete block design.  Replicate plots consisted of 15 ft lengths of bed separated by 3 ft lengths of nontreated bed.  Treatments were applied with a CO₂backpack sprayer that delivered 50 gal/acre at 40 psi to flat-fan nozzles. 
 

Month	Max	Min	Average	Rainfall
January	68	42	54	1.14 in
February	73	47	59	0.50 in
March	77	50	63	0.31 in

 
Downy mildew (caused by Peronospora farinosa f. sp. spinaciae) was first observed in plots on Feb 19  and final reading was taken on February 26, 2024. Spray date for each treatments are listed in excel file with the results.   Disease severity was recorded by determining the percentage of infected leaves present within three 1-ft² areas within each of the four replicate plots per treatment.  The number of spinach leaves in a 1-ft² area of bed was approximately 144. 

The data (found in the accompanying Excel file) illustrate the degree of disease reduction obtained by applications of the various tested fungicides. Products that  provided effective control against the disease include Orondis ultra, Thrive 4 M, Fungout, Cevya, Eject and Zampro. No phytotoxicity was observed in any of the treatments in this trial.

AI is in the news all the time being touted as the most influential human innovation in history. Why? I’m not sure exactly as generally few specifics are given, but recently came across an article that gave me some insight as to what the experts are talking about. The piece focuses on a project by Google DeepMind¹: two AI robots playing soccer (Paul, A., 2024). There’s a couple of things that struck me most about the robots. The first was how human-like their behavior and actions were. They reminded me of a couple of 5-year-olds playing soccer. The second is the manner in which they learned. Unlike traditional programming methods where every action is meticulously coded, these robots were given the objective of scoring a goal and only provided instructions on how to stand up and kick a ball. The rest they taught themselves using deep reinforced learning (AI) methods. The news program 60 Minutes also reported on the AI soccer playing robots (Fig. 1). Check out the article here and the 60 Minutes segment in the video below. I think you’ll be impressed.

Fig. 1. 60 Minutes Segment: Google DeepMind demos AI training robots to play soccer / football. (Credit: 60 Minutes). References

References
Paul, A. (2024). Watch two tiny, AI-powered robots play soccer. Miami, Fla.: Popular Science. Available athttps://www.popsci.com/technology/deepmind-robot-soccer/.
____________________
[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.

Why is it that the summer months we spray herbicides, and they don’t work for some weed species. 

For example, during the hot time of the day and when desert weeds are stressed for moisture even the highest rate of Glyphosate sometimes is not effective.
Some desert weeds develop physical characteristics and growth habits that equip them to survive hot and dry conditions. We have seen that some species have different response to herbicides in cool areas than our low desert. 

Weeds in the desert have a thicker skin to preserve water. The stomates, which are the pores found in the epidermis of leaves, stems, and other organs, controlling the rate of gas exchange between the internal air spaces of the leaf and the atmosphere are closed¹. Plant transpiration is reduced, and this interferes with the translocation of herbicides in the weeds.

Take as an example Purslane, which has very succulent leaves and stems and can survive incredibly high hot and dry conditions. Then when weather is more favorable it comes out of survival mode to start growth again at the presence of moisture.

Other perennial species have underground structures that help them survive such as Nutsedge and bermudagrass have tubers, and rhizomes.
Lundkvist² stated:” The conclusion is that environmental conditions that promote growth rate of the weed stand will also increase the herbicide effect. The results were based on data from two field experimental series performed at six sites in southern Sweden during 1991–1994”.



 References:
1. https://simple.wikipedia.org/wiki/Stomata
2. A. Lundkvist,
Predicting optimal application time for herbicides from estimated growth rate of weeds,
Agricultural Systems,
Volume 54, Issue 2, 1997,

Biological control is one of the key tools for pest management in organic crop production. By maintaining permanent habitats and food sources for the pests’ natural enemies (good bugs) in the vicinity of your farms, you can ensure the continuous availability of the natural enemies. When the growing season starts, the good bugs will be readily available to attack the pests before they become established in the crops. 

Researchers have found that planting a diversity of flowering plants (e.g., sweet alyssum, nasturtium, milkweeds, common cryptantha, hillside vervain, wild petunia, etc.) on a small portion of your farms or the farms’ border can provide adequate food and shelter allowing to maintain abundant and diverse natural enemy species, including syrphid flies, tachinid flies, lacewings, parasitic wasp, etc. that will attack aphids, thrips, lepidopterans, and more. 

As you plan for the next season, please consider planting flowering plants on your farms’ borders or on dedicated patches to conserve natural enemies and enhance your biological control.

Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:            
CEW moth increased the Dome Valley area last week, but areawide below average for early October.
 
Beet armyworm:         
Trap counts highest in Tacan, Wellton and Dome, but below average for early fall.
 
Cabbage looper:          
Cabbage looper numbers remained low consistent with late-September.
 
Diamondback moth:   
DBM moths beginning to appear in traps in Wellton/Dome Valley, trending on average for early fall..
 
Whitefly:                      
Adult movement down in the past week, above average for late-September. 
 
Thrips:                         
Thrips adult activity beginning to increase, and trending about average to previous years.
 
Aphids:                        
First winged adults captured for the season, consistent with heavy winds from W-NW last week. Can anticipate aphid flights to increase in the coming weeks.
 
Leafminers:                   
Adult activity tending downward in most locations, average for late-September.