With the produce season winding down rapidly, now is a good time to reflect on pest activity and insecticide usage you experienced this season in desert lettuce. The 2023 Lettuce Crop Losses Workshop will be held live, in-person Tuesday, May 9^th at the Yuma Agricultural Center from 11:30 until 3:00 pm (see agenda below).  Get there early as lunch will be provided.    The meeting has been approved for 2.5 CA/AZ CEUs.  Participants will be asked to complete two short surveys to document pest pressure and control tactics used on lettuce this season. This workshop has been invaluable to our Vegetable IPM Team over the past 18 years because it allows us to develop accurate “real world” data on crop losses and pesticide usage which is important to the assessment of IPM programs in Arizona. It’s also valuable to PCAs, as it can translate their efforts into economic terms for their growers and confirms their value to the lettuce industry by showing the importance of key insect pests and their cost-effective management in desert lettuce production.  
 
It's no secret, the insect activity this spring was exceptional.  Lettuce aphids and green peach aphids were abundant most of the spring, and thrips numbers were down until late in the season. As I’ve reported previously, I think this may be one of the heaviest aphid years I’ve experienced in the desert in a long time. Earlier Lettuce Insect Losses surveys from theses workshops estimated that over a 18-year period, PCA made on average 1.5 sprays on lettuce for aphids (ranging from 1.0 to 2.5 sprays). For the complete report see:  Insect Losses and Management on Desert Lettuce: An 18-year Summary.  Based on reports from PCAs this spring, it is likely that considerably more sprays were applied this spring for green peach aphid, and perhaps fewer for thrips. Also, a wide variety of insecticides products were reportedly used by PCA’s, some with mixed results. You can review the historical database of insecticides used for aphids and other insects here: Insecticide Usage on Desert Lettuce, 2021-2022  The bottom line: from a historical perspective, it would be quite useful to document insect pressure and sprays applied this year compared to previous years.   In addition to the reporting, Marco Pena will be presenting the latest results of his herbicide trials and areawide weed survey. Finally, I will be providing the latest efficacy trial results on aphids, thrips, worms, and whiteflies. So, we hope you can make it to the workshop and participate in this important process.  
 
 
Lettuce Crops Losses Workshop
 
May 9, 2023       11:30-3:00 pm
 
Yuma Agricultural Center Conference Room
 
Agenda
11:30-12:00 pm          Lunch  (It will be yummy)                                                       
12:00- 12:30 pm         Impact of IPM on Lettuce Insect Losses                                John Palumbo
12:30-1:00 pm             Individual Completion of LIL Questionnaires                       Attendees
1:00-1:30 pm              Historical Results of Insect Losses /Insecticide Usage          John Palumbo 
1:30-2:00 pm              Weed Management Research Update                                  Marco Pena
2:00-3:00 pm              Insect Management Research Update                                  John Palumbo

Every day, each of us generally consumes about 100 gallons of water for our basic needs of drinking, bathing, cooking, toiletries, etc.  (USGS, 2019; Kobir, 2024; and Philadelphia City Government, 2024).  The United States Geological Survey (USGS) estimates that the average American needs 80-100 gallons per day for basic use and consumption (indoor use).  The Arizona Department of Water Resources (ADWR) estimates that Arizonans consume an average of 146 gallons of water per day (ADWR, 2024).
 
As discussed in a recent article in this newsletter (Silvertooth, 2024) the water required to produce the food supporting an average Arizonan can range from 800 to 1,500 gallons per day.  Thus, we can use an estimate of 1,000 gallons consumed per day to support our individual food requirements (Anyabwile and Walker, 2019; Wheeler, 2022; Food Print, 2024; Michel, 2023; Smith, 2012).  
 
If this estimate of “virtual water” use is expanded to include clothing, appliances, vehicles, and other items in our common daily use the average water footprint for Americans easily comes up to 2,000 gallons of water per day (ASPE, 2022).
 
Looking at this more closely, we can see quite a wide range of water requirements to produce some common food items (Figure 1).  It is interesting to note the increasing water requirements associated with meat products and that beef is commonly found at the top of the list.

Figure 1.  Water requirements to produce some common food
items.  Source:  World resources institute, Anyabwile and Walker, 2019.

Considering daily indoor use and diet, a person can develop estimates on their own personal daily water consumption and water footprint by use of one of the water footprint calculators available on-line (i.e., Water Footprint Calculator).
 
Some good examples of water requirements (footprint) for basic food and daily use products include the following (Wade, 2024):
 

• One cup of coffee is estimated to be around 37 gallons. 
• It takes about 365 gallons of water to make Spaghetti sauce with ground beef, garlic, oregano, onion, and basil according to the USDA. 
• Sixty-five gallons of water are needed to produce a serving of rice and beans.
• The fruit in a fruit medley requires 71 gallons of water.
• It takes a total of almost 3,200 gallons of water to produce a mobile phone that includes numerous water-intensive stages, from mining rare minerals to assembling electronic components.  
• A substantial amount of water is needed to provide the ongoing charging required for electric vehicles.  This includes all the steps from the mining of lithium for batteries to manufacturing vehicle components. 
• Approximately 13,700 to 22,000 gallons of water is required to produce each of our standard vehicles.
• The data centers that support the extensive digital landscape we navigate daily require huge amounts of water for cooling systems and infrastructure maintenance.  For every 200 gigabytes of internet access approximately 40 gallons of water is needed, or about one-fifth of a gallon per gigabyte is required.
• A plastic water bottle requires twice as much water to produce the plastic than the volume of water in the bottle.
• One gallon of gasoline requires up to 2.5 gallons of water to refine it.
• One pair of leather shoes requires more than 2,100 gallons of water to produce.

 
The important point to consider is that we all use more water every day than is commonly realized.  Water is essential to support all life and it takes a lot of water to grow plants and support animals that everyone needs to live and survive.  
 
There is a strong demand for the food products shown in Figure 1 and all other food products as well.  As consumers, we are all the direct beneficiaries of 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. 
 
We commonly devour our way through tons of good food while being totally oblivious to the reality of what it takes to put it all in the markets and ultimately on our kitchen tables.  It is good for us to recognize the realities of the water requirements that support the production and provision of our food, particularly in these times of water shortages.

 
References:
Anyabwile, A. and S. Walker.  2019.  5 Ways to put food on a water diet.  World Resources Institute.  https://www.wri.org/insights/5-ways-put-food-water-diet
 
Arizona Department of Water Resources.  2019.  Water Your Facts.  Arizona Water Facts.  https://www.arizonawaterfacts.com/water-your-facts
 
Arizona Department of Water Resources (ADWR).  2024.  Conservation.  https://www.azwater.gov/conservation/public-resources
 
ASPE.  2022.  New research shows most Americans are unaware of their daily water consumption.  ASPE Pipeline.  https://aspe.org/pipeline/new-research-shows-most-americans-are-unaware-of-their-daily-water-consumption/#:~:text=Most%20believe%20they%20use%20less%20than%20100%20gallons,indirectly%20%28e.g.%2C%20the%20water%20required%20to%20produce%20food%29.
 
Food Print.  2024.  The Water Footprint of Food.  https://foodprint.org/issues/the-water-footprint-of-food/
 
Kobir.  2024.  How many gallons of fresh water do we use per day.  https://medium.com/rocklinca/how-many-gallons-of-freshwater-do-we-use-per-day-7987edf6b1bb
 
Michel, D.  2023.  Water and Food: How, When, and Why Water Imperils Global Food Security.  Center for Strategic and International Studies.  https://www.csis.org/analysis/water-and-food-how-when-and-why-water-imperils-global-food-security
 
Philadelphia City Government.  2024.  Gallons Used Per Person Per Day.  https://water.phila.gov/pool/files/home-water-use-ig5.pdf
 
Smith, T.  2012.  World Water Day: How much water do you use in a day?  Climate Home News.  https://www.climatechangenews.com/2012/03/22/world-water-day-how-much-water-do-you-use-in-a-day/
 
United States Geological Survey. 2019.  How much water do I use at home each day? https://www.usgs.gov/special-topics/water-science-school/science/water-qa-how-much-water-do-i-use-home-each-day
 
Wade, M.  2024.  Where does our water wind up?  Ag Alert, California Farm Bureau Federation.  7 February 2024.
 
Water Footprint Calculator. 2024.  https://watercalculator.org/water-footprint-of-food-guide/
 
Wheeler, M.  2022.  Did You Know’ Series: How Much Water Are We Actually Using?  Virginia Water Resources Research Center, Virginia Tech University.  https://www.vwrrc.vt.edu/2022/03/31/did-you-know-series-how-much-water-are-we-actually-using/

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.

Interested in the latest automated weeding technologies? University of California Cooperative Extension will be hosting the 2024 Automated Technology Field Day where twelve of the newest commercial and academic thinning and weed control technologies will be demonstrated in the field. Featured technologies, some showcased for the first time to a general audience, include a high voltage electric weeder that kills weed seed pre-emergence, laser weeders (two types), “smart” precision spot sprayers (four types), “smart” in-row cultivators (four types), and the UA/UC Davis smart steam applicator for killing weed seed and soilborne pathogens pre-emergence. Company representatives and university personnel will be on hand to discuss their equipment. The event will be held from 9:00 am – 12:00 noon, Thursday, June 27^th in Salinas, CA. For additional information, see the event flyer below.

Boerhavia coulteri is a flowering plant that belongs to the Nyctaginaceae or Four O'clock family known by the common name Coulter's spiderling. Its native to the desert areas of the SW in the US and North of Mexico. It is a summer annual or perennial weed producing an erect or creeping stem up to 0.7-0.8 m in length. Grows in disturbed areas, ditch banks, and roadsides.

The cotyledons are oblong,1.0-2.5 cm.

Plants are slightly pubescent with sticky resin glands toward the bases. The leaves are lance-shaped, somewhat triangular, pointed, sometimes wavy or rippled along the edges, and 5 centimeters in maximum length¹.
We have this weed in our Yuma County AZ and very abundantly in the sandy soils of the Yuma Mesa.
I added a table from a weed control experiment conduced for Boheravia erecta.
 
The Research Paper called :” The effect of herbicide tank mix on the weed species diversity
in sugarcane (Saccharum officinarum)” mentions: “All the herbicide mixes significantly controlled Boheravia with Pendimethalin. Being Pendimethalin plus Atrazine the best treatment as shown in the table below.

1. Retrieved from: https://en.wikipedia.org/wiki/Nyctaginaceae
2. Retrieved from: https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=f6c87c4485da5772f26997828b5d4eaf9e856541

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.

Diamondback moth:              

• DBM captures beginning to increase in all trap locations comparable to previous years during September.
• To date, average captures ( < 1 moths / night ) comparable to the 2018-19 growing season
• Moths have been most active in the Yuma Valley where they averaged ~ 1 moth/night in the in traps in both the north and south ends of the valley.
• Comparisons between paired fields showed that a significantly higher number of adults were trapped in transplants (cabbage and cauliflower) compared to direct seeded broccoli.
• Moth activity is 5-fold higher now than this time last year.

Diamondback

We have started our Areawide Insect and DBM Trapping Network for the 2019-20 season.

We have added another trapping location in Bard, CA.

 

Area wide Insect Trapping Network VegIPM Update, Vol. 11, No. 20, Sep 30, 2020

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

 

Corn earworm: Moth activity about normal for September but beginning to increase, particularly in Dome Valley and south Yuma Valley. 

Beet armyworm: Moths remain active throughout the desert, especially in Texas Hill and Tacna growing areas- Staring to pick up in the south Yuma Valley.

Cabbage looper: Cabbage looper activity unusually low for mid-late September. Larvae just starting to show up in some fields.   

Whitefly: Adult movement has been relatively light and about average for this time of year. Activity highest in Dome Valley. 

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: No aphids have been caught on traps thus far. Normal for this time of year.  Still early, anticipate they will begin to show up in 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.