Hope you are all enjoying the summer so far and keeping busy. Although, we’re about 2 months away from the Fall produce season, it’s never too early to begin thinking of IPM strategies you will be using to battle key insects next season. This includes keeping track of their typical activity during June, July, and August. Below is a short discussion detailing individual pests. 
 
Aphids:    The major aphid species that are important in produce crops each spring include green peach aphid, foxglove aphid and lettuce aphid.  These species are considered cool season pests and are biologically most active during the winter and spring when temperature average around (55-65 F). We do not find them on summer crops as the high temperatures prohibit their activity. They essentially become extinct each summer only to reappear in the fall to infest crops in Oct-Dec migrating into the desert via N-NW winds that occur after the monsoons.
 
Diamondback Moth (DBM):  Another key pest that disappears each summer but for a different reason than for aphids. The host range of DBM is limited to only brassica crop and plants. Although brassica weeds are common during the winter, they occur during the summer due to high temperatures and dry conditions. Thus, like aphids, DBM populations from the previous spring season become “extinct” during the summer when brassica crops and weeds are absent. They reappear each fall migrating in on high winds associated with tropical storms from Mexico, or arrive into the region on infested brassica transplants from California.
 
Whiteflies:       A resident pest that occurs year-round in the desert. As a warm season pest, whiteflies are most abundant on fall produce crops, and seldom a problem during the winter and spring. Peak abundance occurs during the summer months on cotton, and again in September and October on fall brassica, leafy vegetables and fall melons.  Thus, it is important to control whiteflies in cotton prior to defoliation to prevent large migrations onto fall produce crops. In addition, whiteflies can be found on several weeds such as purslane, goosefoot, ground cherry, and sunflowers. Sanitation in and around fields being prepped for fall plantings is important. Preventatively, growers should consider applying soil, system insecticides such as imidacloprid or Verimark to Fall produce crops.

Beet Armyworm (BAW):  A warm-season pest that occurs year-round in the desert. They tend to reach peak abundance twice a year. Generally, the most important peak is in September and October when weather is ideal for their development, flight activity and oviposition. A second peak occurs in late spring. Activity is generally light during the summer, occurring primarily in alfalfa crops. Although BAW is known to migrate in from the south via monsoon and tropical storms, resident populations annually occur in alfalfa during the summer. Thus, to minimize BAW in fall produce crops, thorough management of BAW can potentially minimize their movement onto Fall produce crops.  Weeds are also a source of BAW (purslane, goosefoot, sunflower and Russian thistle) so sanitation in and around fields is important.
 
Western Flower Thrips (WFT):  Also a resident pest that can be found in the desert year round. WFT is most abundant on lettuce in the late spring, but peaks in abundance on alfalfa, melons and cotton is May and June. During the late summer numbers drop dramatically where thrips can be found on melons and alfalfa and weeds like goosefoot and purslane. WFT slowly move into lettuce again in early fall and are least abundant during the winter.  Sanitation of weeds during the summer can help reduce thrips abundance moving into the fall crops and weeds.
 
For more information see:   Keeping Track of Major Produce Pests During the Summer

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/

Fungal transmission of viruses: 
Several viruses have been shown to be transmitted by soil-inhabiting fungi and protists. Two of the common fungal species that transmit viruses in vegetable cropping system are Olpidium spp. and Polymyxa spp. There is specificity between the zoospores of the fungi and virus particles for successful transmission to occur. Not all soilborne fungi can transmit viruses.
 
Olipdium brassicae  is an obligate parasite, meaning the fungus always needs a host plant to survive (brassicae, cucumber, carrot, lettuce). The fungius that act as vector of s viruses survive the time in between crops by producing resting spores.  A virus that we  often see in the desert, Lettuce big vein virus, is transmitted fungus  Olpidium brassicae . Lettuce big vein virus is acquired by the zoospore (motile spores)  as well as resting spores of the fungus. 
  
The other soilborne virus  we see in the desert it Tomato bushy stunt virus is soilborne but has no known vectors. Thought it was predicted to be transmitted by a fungus Olpidium brassicae, new research findings have rules out the particular fungal vector. But there is a possibility that the virus has some soilborne vector. 
 
Common viruses with fungal vector: 
Cucumber necrosis virus: Olpidium bornovanus
Beet necrotic yellow vein virus: Polymyxa betae
Beet soilborne mosaic virus: Polymyxa betae
Beet soilborne virus:Polymyxa betae
Beet virus Q: Polymyxa betae

Nematode transmission of viruses
Two genera of viruses; Nepoviruses (Nematode transmitted polyhedral viruses) and Tobraviuses (Tobacco rattle virus) are transmitted by nematodes.  Xiphinema (Dagger nematodes), Longidorus (needle nematodes), Trichodorus and Paratrichodorus (stubby root nematode) vector transmit different species of viruses. 
 
Virus transmission by nematodes happens in 7 different but interrelated steps. 

1. Ingestion: The process where the nematode ingests the virus particle along with the plant material/sap. 
2. Acquisiton: The unique receptor in the nematode identifies the virus, so he virus particles stay intact within the nematode. 
3. Adsorption: The phenomena of the virus being intact instead of disintegrated in the nematode digestive system. 
4. Retention: Once adsorption, the virus particle can be retained in nematodes anywhere from months to even years. 
5. Release: The virus particles are released onto new plants when nematodes commences feeding on new plant. 
6. Transfer: The virus particles get transferred to new plant. 
7. Establishment: The virus particles establish themselves in the new host plant. 

 
It is a sophisticated and thankfully a very specific relationship. Not all nematodes transmit virus, neither do nematodes vector all plant viruses. Nematodes and nematode transmitted viruses are of a bigger problem in perennial agriculture system such as citrus orchards and grapevines. 
Viruses transmitted by nematodes: 
tobacco rattle virus: beans, beets, peppers, potatoes, and spinach and 100 others
tomato ringspot virus-tomato, cucumbers, 
peach rosette mosaic virus: peach, blueberries 
cherry rasp leaf virus: cherry, apple
grapevine fanleaf virus: grapes and grape hybrids

Seed transmission:  About 1/7 th of the known plant viruses are transmitted through seeds. Different viruses have different host ranges (the plants that they can infect). Tobacco mosaic virus, Cucumber mosaic virus are some viruses with a very wide host range and they may not be seed transmissible in all plants they infect. Seed transmission plays a huge role in virus epidemiology. Not only they can be a primary source of infection, leading to an epidemic in the field upon conducible environment, seed transmission is an effective way for long distance travel of the virus, thus introducing the virus to new places. You have heard of USDA regulations/restrictions on different crops, from certain foreign countries to avoid introduction of infected seeds/plant materials. 
 
Seed transmission can occur simply by contamination of seeds, as in tomato seeds by Tobacco mosaic virus. This can be readily inactivated by seed treatments. 
The second type of seed transmission occurs when the virus is present in the embryo tissue that can happen prior to fertilization or takes place at pollination. Pea seed-borne mosaic virus is a well studied plant virus in this category. 
 
 
Pollen Transmisison:  Some viruses are transmitted from plant to plant via pollen. As in seed transmission, pollen transmission has two mechanisms, gametic infection of embryo and direct infection of mother plant. 
 
Vegetative propagation: An important horticultural practice, and unfortunately a very effective method for perpetuating and spreading viruses. In clonally propagated plants, an infected mother plant which could be asymptomatic could be used to make hundreds and thousands of daughter plants, which will all have the virus. Any vegetative parts  such as bulbs, corms, runners, and cutting will be infected. 
 
Grafting: Essentially a form of vegetative propagation, once the organic union has been established and plants (Scion and Stock) function as a single plant. In experimental front, grafting is used as a virus transmission methods, when all other methods fail.

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.
 
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.