The 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 commonly used insecticide class. No surprise there. Over the past 15 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, plant bugs and some Lepidopterous larvae and adults (looper and corn earworm). The overall use of OPs and carbamates continues to decline and decreased slightly compared to 2018-19. Methomyl (Lannate) usage was similar to the previous three years, but acephate usage noticeably decreased on spring lettuce this season lighter thrips pressure. 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 15 years, averaging over 2 sprays per treated acre, and remained high in 2019-20. 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 usage increased by about 20% on fall lettuce in 2019. Another important class of chemistry used in fall and spring lettuce are the neonicotinoids (the 3rd most used chemistry in lettuce in 2019-20) 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, but usage last season decreased significantly where it was used on less than 80% of lettuce acres. The usage of imidacloprid on both fall and spring lettuce has increased markedly since 2009, but usage decreased last season where it was used on less than 70% pf lettuce acers. Although less Movento was used on fall and spring lettuce in 2019-20, it remains second most applied product for sucking insect control. An increase in Sequoia was reported in spring 2020 and was to about 45% 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 commonly used insecticides on fall and spring lettuce this past growing season, go to Insecticide Insecticide Usage on Desert Lettuce, 2019-2020.

Please provide the common and scientific name for this insect.

This time last year we were experiencing extremely high fertilizer prices that were continually rising.  Fertilizer prices had been steadily increasing throughout 2021 and then experienced an acceleration after the Russian invasion of Ukraine in February 2022.  Throughout the desert Southwest and across the nation, high prices have continued for fertilizers used in crop production agriculture over the past year.  Now in early 2023 fertilizer prices are starting to decline but are still relatively high compared to prices two years ago.  These patterns are shown in Figure 1.
 
There are at least four important lessons or messages from these recent experiences with global fertilizer prices and the impacts at the field level in crop production systems.  First, many people have come to recognize that among global nitrogen (N), phosphorus (P), and potassium (K) fertilizer producers China, Russia, and Belarus are major players and are consistently in the top 10 (Figure 2).  Our awareness has been heightened in response to the diminished supply available to U.S. markets from these three nations in the past year.  The U.S. ranks fourth in overall N, P, and K fertilizer production.
 
Secondly, as fertilizer use has increased in many parts of the world in the past 60 years, the U.S. now represents only 10% share of the global use of N, P, and K fertilizers (Figure 3).  
 
The third point that has been emphasized and has become increasingly clear to the crop production industry, is the connection between fertilizer production input costs, particularly natural gas, and fertilizer prices (Figure 4).  Fertilizer production facilities require a large amount of energy to convert the raw chemical materials into their applicable farm-use state. This is very important in terms of N fertilizers. 
 
Regarding prospects for global fertilizers, experts in the industry have the common variance in points of view but there seems to be a general agreement that higher prices have been a function of reduced supply and that was further exacerbated by the Russia-Ukraine war, the loss of a major port for Belarus potash fertilizer, and the P fertilizer supply constraints from China (Baffes and Koh, 2023).
 
These pressures are not going away soon, but the impacts have diminished in recent months.  The constraints on supplies of P and K fertilizers are expected to continue for quite some time into the future.  Price reductions have been most notable for N fertilizers, primarily due to lower natural gas prices in Europe compared to 2022.
 
Crop Nutrient Management
The fourth point of emphasis regarding fertilizer prices and desert crop production systems has been the shift towards more conservative management of fertilizers in the field.
 
Developing a conservative approach to nutrient management is often considered a risky venture in crop production systems, particularly with a short season crop like a leafy green vegetable that has a premium on quality as well as yield. However, under high fertilizer price conditions and/or tight supply, there is a greater incentive to develop and employ a more conservative approach to nutrient management.
 
To maximize nutrient management efficiency, the 4R concept of plant nutrient management and application can be helpful.  The 4R concept consists of applying:
 
 1.   The Right fertilizer source at the
 2.   Right rate, at the
 3.   Right time and in the
 4.   Right place
 
Along with the 4R nutrient management approach, an assessment of plant-available forms of the nutrients present in the soil by evaluating soil tests with appropriate indices is a good step in the development of a more efficient nutrient management program.  Then splitting nutrient applications, particularly mobile nutrients such as N in line with crop uptake and utilization patterns are good steps towards higher fertilizer use efficiency by the crop.  Thus, timing, methods, and rates of nutrient applications are critical (i.e., 4R management).
 
In agriculture we know quite well that we have no control over markets and the costs of crop production inputs.  However, we can control these inputs in the field, and we do have some tools at our disposal that can be helpful in the process.
 
References:
Baffes, J, W. C. Koh.  2023.  Fertilizer prices ease but affordability and availability issues linger.  5 January 2023, World Bank.  https://blogs.worldbank.org/opendata/fertilizer-prices-ease-affordability-and-availability-issues-linger
 
Crawford, A, F. Jomo, E. Elkin, and M. Bristow. 2023.  World’s fertilizer market in turmoil.  Bloomberg, Farm Progress, 20 February 2023.  https://www.farmprogress.com/crops/world-s-fertilizer-market-in-turmoil
 
Quinn, R. 2023.  DTN retail fertilizer trends.  DTN Progressive Farmer, 15 March 2023.  
https://www.dtnpf.com/agriculture/web/ag/crops/article/2023/03/15/anhydrous-uan-move-even-lower?referrer=NLSnapshot

Figure 1.  Average weekly retail prices for anhydrous ammonia (82% N), for
2021, 2022, and through 10 March 2023.  Source: DTN/Quinn, 2023.


Figure 2.  Ranked nitrogen, phosphorus, and potassium fertilizer production by
country.  (FAO and Bloomberg graphics).  Crawford et al., 2023.



Figure 3.  Pattern of U.S. share in the global nutrient market since
1961.  Source: Farm Bureau.


Figure 4.  Fertilizer input cost trends, 2019-2022.  Source: Bloomberg; World
Bank.  Baffes and Koh, 2023.

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.

With the advent of low-cost computing systems that can identify and locating crop and weed plants in real-time, there’s been an explosion in the interest, investment and development of technologies for robotic/automated weed control. A quick internet search will reveal over 50 companies or university research groups working in this space. You are probably familiar with many of these as they are domestically based and have been discussed in previous articles, but there are also numerous efforts being made in Europe that may be of interest. One of these is highlighted here. In future articles, I’ll discuss additional technologies. 
Andela Techniek & Innovatie¹ is a Dutch company who appears to be making good progress with an innovative robotic weeding machine (Fig. 1). The solar powered device spans 29.5 feet and is equipped with 12 robotic delta arms for removing in-row weeds (Fig. 2). A camera-based imaging system is used to differentiate crop plants from weeds and provide coordinates of targeted weeds to the delta arms. Each delta arm is equipped with an end-effector that uses heat to kill the weed when it comes into contact with it. A company video showing the device operating in carrot and onion crops can be found by clicking here or on the images below. 
Stay tuned!

 

Fig. 1. Andela Techniek & Innovatie1 solar powered robotic weeding machine. (Photo credits: Andela Techniek & Innovatie)


Fig. 2. Delta arms and end effector of Andela Techiek &
Innovatie¹ robotic weeding machine. (Photo credits:
Andela Techniek & Innovatie)

Do you know the botanical families of all the small acreage specialty crops grown in the low desert?
The family is an important factor in deciding what type of herbicides can be used for weed control in our crops. For some of us it has been difficult to keep track of the families. I found a table published in this Newsletter by our Applied Weed Science maestro Barry Tickes. 

Hope you like the chart with the botanical families of many of these crops and herbicides that might be used on them.

Botanical Family	Crops	Possible herbicides (check label)
Brassica	Bok Choy, Napa, Mizuna, Kale, Kohlrabi, Turnip Greens, Mustard, Tatsoi, Arugula, Radish, Daikon	Prefar, Trifluralin, Dacthal, Stinger, Poast, Select
Umbelliferae	Cilantro, Celery, Coriander, Parsley, Dill, Parsnip, Fennel	Prefar, Lorox, Poast, Prometryne
Aster	Endive, Escarole, Chicory, Radicchio	Prefar, Trifluralin, Kerb, Fusilade, Poast, Select
Amaranth	Spinach, Chard, Beets	Roneet, Dual Magnum, Poast, Select

 

Area wide Insect Trapping Network   VegIPM Update, Vol. 15, No. 20, Oct 2, 2024
 
Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:             
CEW moth counts low in most traps; below average for this early produce season. 
 
Beet armyworm:         
Trap counts decreasing in most areas, and below average for late September
 
Cabbage looper:          
Cabbage looper trap counts low in all locations, typical for mid-late September.
 
Diamondback moth:   
Adult activity beginning to pick up in Dome Valley.  Overall, typical of late September with minimal monsson activity.
 
Whitefly:                       
Adult movement most active in Dome Valley; overall below average for mid September
 
Thrips:                          
Thrips adult movement light; overall activity typical for September. 
 
Aphids:                        
Aphid movement absent so far; anticipate activity to pick up when winds beginning blowing from N-NW. 
 
Leafminers:                  
Adult activity light in all areas, about average for this time of season.