Since 2013, Dr. John Palumbo’s area-wide trapping network has given growers a regional view of pest movement across the Yuma Valley and lower Colorado River region. His work set a new standard for vegetable IPM in the desert Southwest—shaping how we monitor and respond to pests at the landscape level.

That same philosophy now powers a new generation of digital tools that make trapping data accessible across the western vegetable-growing region:

• Salinas Pest Map
• Imperial Valley Pest Map

Note: A mobile and desktop version of these pages are available. You can switch between versions using the option at the top of the page.

Both dashboards visualize weekly trap data for key pests like whiteflies, thrips, aphids, and lepidopterous larvae. Users can explore where and when pest activity is increasing which helps fine-tune scouting and spray timing across the landscape.

How to Use the Maps

1. Choose a pest from the dropdown list.
2. Use the time slider to scroll through the season and watch population changes.
3. Hover over trap sites to see weekly counts.
4. View charts below the map to track overall trends or compare seasons.

A Yuma version will launch later this season, integrating John’s historical trapping data to continue his vision of landscape-scale pest management in desert vegetables.

Explore the tools:
Salinas Pest Map | Imperial Valley Pest Map


To contact Macey Keith go to: maceyw@arizona.edu

Root systems are responsible for all water and nutrient uptake by the plant and they provide the physical anchoring and support of the plant structure.  Each plant and crop species has its own “personality” and growth habits, and root systems have unique characteristics among plants species.  
 
In general plant root systems constitute 30-50% of the total plant dry matter.  When post-harvest plant residues are incorporated into the soil, the root systems provide a significant contribution to that plant material and final carbon (C) contributions to the soil.
 
The first thing a seed develops in the germination process is a primary root that grows downward into the soil.  We often refer to this as the “stinger” root that extends from a germinating seed.  New cells are formed at the tip of the primary root as it extends downward into the soil forming a “thimble-shaped” cluster of cells called a root cap (Figure 1).  The root cap serves as a type of shield that helps the root penetrate the soil matrix and protect the developing root tissue.  As the root grows downward into the soil the root cap cells are sloughed off creating a slimy surface that helps lubricate the root as it extends deeper.
 
The growing point (apical meristem) for the developing root is just behind the root cap and this is the zone of new cell formation that facilitates root growth and replaces the cells that are sloughed off as the root grows through the soil.  The new cells elongate and serve to extend the roots into the soil (Figure 1).
 
The most active parts of the plant root system for mineral nutrient and water uptake are in the tiny root hairs that are formed in zone behind the apical meristem.  Root hairs are only formed in the relatively new and freshly developed root tissue.  The root hairs are extremely small, tender, and physiologically active.  Root hairs are often referred to as “feeder roots” due to their high-level of activity in securing water and nutrients from the soil for the growing plant.  In the process of transplanting, it is important to protect the feeder roots and promote their health to ensure rapid adaptation to the new soil environment.
 
Young plants have the capacity to develop basic aboveground tissue to perform sufficient photosynthesis for establishment and growth due to the plant’s ability to take up mineral nutrients and water from the soil from the root system.  Sometimes it can appear that plants are not growing rapidly while the young crop is investing energy and resources into root system development, which is the foundation for the subsequent plant growth and development.
 
The depth of the roots will vary according to the soil physical conditions and effective soil depth, soil fertility and salinity management, plant-available water, and of course the natural rooting characteristics of the plant.
 
In general, there are two basic types of plant root systems.  Broadleaf plants (dicotyledonous) and coniferous plants (gymnosperms) commonly have a taproot system the extends downward through the soil developing root branches from the primary root stem (Figure 2).
 
Grass plants and their relatives (monocotyledonous plants) produce fibrous root systems that branch extensively and radiate out into the soil from the plant base (Figure 2).
 
In general, taproots tend to be deeper with extensive branching from the primary root, develop woody tissue on older roots, and generally long-lived.  In contrast, fibrous roots tend to be smaller, short-lived, with less branching.  As roots age, they become more important in conducting nutrients and water to the growing points of the plant, both above and belowground.  In all cases, the young and freshly developed root hairs (feeder roots) are the primary zone of water and mineral nutrient uptake.
 
As root systems age, the older roots will die, and new root tissue is formed.  As dead roots are sloughed off, the discarded tissue is attacked by naturally occurring, beneficial soil organisms (bacteria, fungi, protozoa, and worms) the release mineral nutrients and produce soil organic matter.  Turnover of root tissue is an extremely important aspect of plant contributions to soil carbon (C) and organic matter.
We do not see the plant root system on a regular basis and we cannot watch root hair development.  But it is good to be conscious of root system development since all mineral nutrient, water uptake, and structural support is provided through the roots. So, it is good to review and understand root structure and function as we work to manage crop plants for optimum growth and development.

Figure 1.  Basic root tip anatomy.


Figure 2.  Examples of taproot and fibrous root systems.

On March 30th, I shared a newsletter highlighting an increase in celery samples exhibiting symptoms consistent with black heart and black streak abiotic disorders, associated in timing with the mid-March heat wave. At that time, affected plants showed elongated necrotic pitting accompanied by pronounced horizontal cracking along the inner petioles. In more severe cases, there was complete breakdown of young tissues within the heart, including petioles and emerging leaves. Importantly, diagnostic testing on those early samples returned negative results for the common viral pathogens typically considered in the differential diagnoses fitting these symptoms. 

Early black heart symptoms 


Late black heart symptoms + secondary colonization 

Black streak of celery

The YPHC has since received a new sample that changes part of that picture. This most recent submission tested positive for celery mosaic virus (CeMV). In addition to sunken discolored stalk lesions that could potentially be mistaken for early black heart or black streak, the plants in this sample exhibited severe foliar symptoms. Leaf symptoms included deformation including curling and marginal distortion. The leaves also showed distinct mosaic patterning, yellowing, and streaking, all of which are typical characteristics for viral infections. 

Sunken, discolored lesions on celery petioles 


Broad yellowing and mosaic pattern (left) and severe leaf distortion
and mild mosaic (right) on the foliage 

Mosaic, yellowing, and leaf distortion combined on the same petiole

Additional symptoms associated with CeMV can include overall plant stunting and abnormal growth habit (Greer et al. 2024). In some cases, outer petioles may distort severely and begin growing horizontally, giving the plant a flattened appearance. Symptom severity can vary depending on the strain of the virus and environmental conditions during host infection. Be on the lookout for these additional foliar symptoms if you’re seeing sunken petiole lesions as a possible indicator of viral infection. Early infections, symptoms on different varieties of celery, or symptoms caused by different viral strains of CeMV may not look identical in severity or expression as the sample photographed here. CeMV is transmitted by aphids in a non-persistent manner and may also be spread mechanically through wounds introduced during field activities (Karanfil & Randa-Zelyüt 2025). It has not been reported to be seedborne. Fungicides are not effective against plant viruses, and while insecticides may reduce aphid populations, they are generally not effective at preventing virus transmission due to the rapid transmission following the initiation of aphid feeding that occurs before the insecticide has a chance to act on the vector (Greer et al. 2024). We will continue monitoring all incoming celery samples to determine whether this represents an isolated case or a broader trend developing alongside the ongoing celery abiotic disorders.

Sources and further reading:
Greer, C., Koike, S., & Turini, T. “Celery Mosaic Virus.”  Agriculture: Celery Pest Management Guidelines. University of California Agriculture and Natural resources, 2024. URL: https://ipm.ucanr.edu/agriculture/celery/celery-mosaic-virus/#gsc.tab=0 (Accessible 4/28/2026)

Karanfil, A., & Randa-Zelyüt, F. “Celery Mosaic Virus.” Compendium of Phytopathogenic Microbes in Agro-Ecology. Springer Nature, 2025. 153–160.

If you have any concerns regarding the health of your plants/crops please consider submitting samples to the Yuma Plant Health Clinic for diagnostic service or booking a field visit with me:

Christopher Detranaltes, Ph.D.
Cooperative Extension – Yuma County
Email: cdetranaltes@arizona.edu Cell: 602-689-7328 6425 W 8th St Yuma, Arizona 85364 – Room 109 

 

We are in the process or organizing our 3^rd AgTech Field Day. The event will be held Tuesday, October 25^th at the University of Arizona’s Yuma Agricultural Center. Like last year, the workshop will feature the latest ag technologies being demoed in the field. I’ve been reaching out to multiple companies but am sure I’m not aware of all the cutting-edge technologies out there. We’d like to showcase as many innovative ag technologies as possible, so please contact me if you are interested in demoing your equipment or know someone that is. It’s an open invitation - private companies, and university and government researchers are all welcome.

Fig. 1. AgTech Field Day (2021).

Prefar 4-E (bensulide) is one of the old standard selective preemergent herbicides that have been used on lettuce for more than 50 years. It was developed by Stauffer and first registered for lettuce in 1968, acquired by Zeneca (ICI) in 1992 and its now a Gowan product since 1996. It is one of the few organophosphates (OP) that are used as an herbicide.
 
Bensulide controls weeds by interfering with the normal germination and seedling development. It inhibits cell division at the growing points of the roots and does not translocate or move upward into the rest of the plant. 
It is an emulsifiable concentrate that is applied at 4 to 6 qt. per acre and its only effective if the roots contact the herbicide soon after they have started to grow. It performs well on annual grasses, Purslane, Pigweed, and has activity on nettleleaf goosefoot and common lambsquarters.
 
Label recommendation is to spray to a well-prepared soil a uniform spray pattern in a 10-50 gallons per acre.
It is recommended to apply the higher labeled rates to heavier fine textured soils.
Prefar works much better when incorporated with sprinklers and requires high volumes of water. It also works best in coarse textured soils.
It must be incorporated into the top inch or two of soil only where the roots would be exposed to the herbicide right after they have begun to grow.
 
It was reported in this Newsletter that a 2017 USDA survey showed that Prefar is used in 11% of the lettuce in AZ and CA. For the same period in Yuma CO approximately 58% of the lettuce was treated with bensulide. 
 
The Vegetable IPM Team at the Yuma Agricultural Center will be conducting trials this produce season on the application timings and methods for this important herbicide. Will keep you updated so, stay tuned!.

VegIPM Update Vol. 17, Num. 9
April 29, 2026

Results of pheromone and sticky trap catches below!!

Corn earworm:  CEW numbers remained steady at most locations over the last two weeks. CEW is active throughout the summer and high numbers are expected leading into the next produce season.

Beet armyworm:  BAW activity remained steady over the last two weeks. Historically adult BAW is collected through the summer, although numbers are lower compared to Mar-Apr seasonal highs.

Cabbage looper:  Cabbage looper moth activity remained steady over the last two weeks. Numbers are expected to decrease as temperature gets warmer.   

Diamondback moth: Adult DBM numbers continued to decrease across most locations. Based on other years data, DBM numbers are expected to continue decreasing as cole crops acres decrease.  

Whitefly: Adult activity remains steady across all locations, about average for this time of year. Expect numbers to continue increasing as temperatures warm up.  

Thrips: Adult thrips activity remains steady across locations. Historically, western flower thrips numbers peak in May.  

Aphids: Winged aphid numbers continued to decrease at most sites in the last two weeks. Winged aphids disappear from our traps after April as temperatures become too hot for aphids.  

Leafminers: Adult leafminer activity decreased over the last collection. Leafminers are collected in our traps throughout the summer.