Results from our annual Lettuce Insect Losses surveys continue to show interesting trends in insecticide usage on desert lettuce. In general, the most used insecticides in fall and spring lettuce correspond directly to the key pests that typically occur during these growing periods. Overall, the pyrethroids applied both as foliar sprays and through chemigation at stand establishment were the most used insecticide class. No surprise there. Over the past 17 years, pyrethroid usage has remained steady and the reason is quite clear. Pyrethroids are the most inexpensive and safe broad-spectrum insecticides still available for use in tank-mixtures for effective control of beetles, crickets, and some plant bugs. The overall use of OPs and carbamates increased compared to 2019-20. On spring lettuce, methomyl and acephate usage was higher than the previous 4 years, likely due to the threat of INSV on late plantings. In the past few years, OPs/carbamates have been increasingly replaced by several reduced-risk chemistries, of which the spinosyns are the most used class of selective insecticides. Radiant usage against both lepidopterous larvae and thrips has remained steady over the past 17 years, averaging over 2 sprays per treated acre, and remained high in 2020-21. The use of spinosyns against both lepidopterous larvae and thrips has remained steady since they were first registered. The Diamides (Coragen, Besiege, Minecto Pro, Exirel and Verimark, and Harvanta) were another commonly used selective chemistry in lettuce this season. Since they were first registered in 2008, PCAs have steadily incorporated this new chemical class into their management programs and were used on > 80% of the fall lettuce in 2020. Another important class of chemistry used in fall and spring lettuce are the neonicotinoids (the 3rd most used chemistry in lettuce in 2021) driven primarily by soil-applied imidacloprid for whiteflies and aphids. The usage of imidacloprid on both fall and spring lettuce has increased markedly since 2009 and increased last season where it was on 80% of fall and spring acres. Foliar neonicotinoid usage increased slightly last season on fall lettuce was down in the spring. However, Movento was applied on a greater number of spring acres in 2020-21 and remains second most used product for sucking insect control. Sequoia, Sivanto, and PQZ accounted for significant usage this spring and were applied to 33.3, 23.9, and 19.2% of the acreage respectively. Torac usage was up slightly last spring for thrips management but was only used on less than 5% of the acreage. Finally, among all insecticide chemistries, the broad spectrum, consumer–friendly pyrethroids have been the predominant chemistry applied to lettuce. However, for the past eight seasons PCAs treated a greater percentage of their lettuce acreage with selective, reduced-risk products than with the broadly toxic, OP/ carbamate chemistries. To view a summary of the estimated insecticide usage by chemical class, as well as the most used insecticides on fall and spring lettuce this past growing season, go to Insecticide Usage on Desert Lettuce, 2020-21

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.

Fusarium wilt of watermelon, caused by Fusarium oxysporum f. sp. niveum,  is one of the oldest described Fusarium wilt diseases and the most economically important disease of watermelon worldwide. It occurs on every continent except Antarctica and new races of the pathogen continue to impact production in many areas around the world. Long-term survival of the pathogen in the soil and the evolution of new races make management of Fusarium wilt difficult. 
In 2022, we had  a lot of watermelon fields infected with Fusarium from Winterhaven to Yuma, Wellton, and Mohawk Valley. Rain, and overwatering of fields when plants set fruits might have contributed to the disease development. It is always a good idea to look out for any potential diseases that might occur this year! 
 
Symptoms of Fusarium can sometimes be confused with water deficiency, even though there is plenty of water in the field. In Yuma valley we have seen fusarium problem in some overwatered fields. 
Initial symptoms often include a dull, gray green appearance of leaves that precedes a loss of turgor pressure and wilting.  Wilting is followed by a yellowing of the leaves and finally necrosis.  The wilting generally starts with the older leaves and progresses to the younger foliage. Under conditions of high inoculum density or a very susceptible host, the entire plant may wilt and die within a short time.  Affected plants that do not die are often stunted and have considerably reduced yields.  Under high inoculum pressure, seedlings may damp off as they emerge from the soil. 
 
 Initial infection of seedlings usually occurs from chlamydospores (resting structure)  that have overwintered in the soil.  Chlamydospores germinate and produce infection hyphae that penetrate the root cortex, often where the lateral roots emerge.  Infection may be enhanced by wounds or damage to the roots.  The fungus colonizes the root cortex and soon invades the xylem tissue, where it produces more mycelia and microconidia.  Consequently, the fungus becomes systemic and often can be isolated from tissue well away from the roots. The vascular damage we see in the roots is the defense mechanism of the plant to impede the movement of pathogen. 
 
Disease management include planting clean seeds/transplants, use of resistant cultivars, crop rotation, soil fumigation, soil solarization, grafting, biological control. An integrated approach utilizing two or more methods is required for successful disease management.

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/.
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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.

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,

Integrated pest management (IPM) involves the utilization of a combination of several tactics for the effective management of pests. This concept was developed by entomologists and is currently adopted by pest managers to target many kinds of pests, including insects, weeds, and pathogens. Most IMP tactics fit well in both conventional and organic crop production. It is not uncommon that most pest management techniques that are approved for organic crop production are not very effective as a stand-alone tactic. Therefore, it is essential to use a combination of pest management techniques that will complement each other to control the pests adequately. This is like a many little hammers approach, where each of the management tactics is a little hammer hammering on the pests. When planning your IPM programs targeting pests in organic crop production, it is important to consider planting resistant/tolerant varieties, scouting regularly, implementing economic thresholds (when possible), practicing cultural control, physical/mechanical control, and biological control, and applying biopesticides when necessary. 

• Resistant varieties: Resistant varieties are crucial for effective IPM in organic crop production. When available, the use of resistant varieties should be the first line of defense against pests. Resistant varieties help save on production costs and mitigate environmental impacts associated with insecticides and their applications. 

• Cultural control: Cultural control includes cropping systems (trap cropping and push-pull), planting date (early planting or late planting), crop rotation, and growing of crop varieties with early maturity traits. Implementing trap cropping and/or push-pull systems can cause the diversion of insect pests. Early or late planting, crop rotation, and variety with early maturity traits can favor the avoidance of damaging insect pest pressures. 

• Scouting: Proper and timely scouting helps determine the levels of pest infestations, allowing the pest manager to trigger control action in a timely fashion. Scouting also helps to prevent unnecessary insecticide applications. 

• Economic thresholds: The economic threshold determines the pest or injury level at which control action should be taken. The economic threshold works side by side with scouting. This helps to determine when a management action should be triggered, allowing a reduction of unnecessary insecticide utilization, which will consequently help in delaying or mitigating resistance. 

• Physical/mechanical control: This method includes establishing physical barriers, plowing, and sanitation (elimination of volunteer crops and other potential hosts). Plowing can help to bury soil insect pests deep into the ground, directly kill them, and expose soil insects to adverse weather conditions, birds, and other predators, which will adversely impact these pest populations. 

• Biological control: This method involves using insect pests’ natural enemies, including predators such as spiders, lady beetles, syrphid fly larvae, big-eyed bugs, pirate bugs, lacewing larvae, and parasitoids such as parasitic wasps and flies. 

• Biopesticides: Biopesticides are based on botanical extracts, entomopathogenic fungi, entomopathogenic bacteria, or entomopathogenic viruses that have adverse effects on insect pests. Entrust, Bt, Pyganic, AZA-Neem, M-Pede, Celite, and Venerate are commonly used insecticides for insect pest control in organic crops grown in Arizona. 

The implementation of IPM permits to manage pests economically while preserving the environment and reducing negative impacts on human health. In other words, IPM aims at managing pests in an economically viable, socially acceptable, and environmentally safe manner. It is important to note that all the IPM tactics are not always viable in all situations (IPM is not a one-size-fits-all). Therefore, the management techniques choice for an IPM program should be done on a case-by-case basis. 

Area wide Insect Trapping Network   VegIPM Update, Vol. 15, No. 21, Oct 16, 2024

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

Corn earworm: CEW moth counts increased in most traps; about average for early October.

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

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

Diamondback moth: Adult activity increasing, particularly in the Yuma and Dome Valleys.  Above average for this time of season.

Whitefly: Adult movement increasing Tacna, Dome Valley and Yuma Valley; overall about average for early October.

Thrips: Thrips adult movement picking up in all areas, overall activity above average.

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

Leaf miners: Adult activity light in all areas, about average for this time of season