As you plan for the season, it’s important to know how EPA’s new Endangered Species Act risk mitigations might impact pesticide planning and use.

As EPA registers new pesticides or reviews registrations of existing ones, they evaluate expected impacts on federally listed threatened and endangered species. When a pesticide is predicted to adversely affect a listed plant or animal species or their critical habit, one or both of two outcomes are possible:

1. Broad label requirements to reduce potential impacts of pesticides on listed species and other non-target organisms by reducing runoff and/or spray drift.
2. Geographic-specific use limitations communicated through

Bulletins Live! Two.

As you plan your pesticide program, be sure to review current product labels to anticipate any endangered species requirements.

 

Runoff Mitigation Points

• Does the pesticide require runoff / soil erosion mitigation points? Check the pesticide label. (Tip: Look for a header such as “Mandatory Runoff Mitigation” or search for the word “points.”)

• Exemptions. No points are needed for fields with systems that capture runoff and discharge, certain application methods such as soil injection, spot treatment < 1,000 sq. ft., or chemigation applied under non-permeable plastic mulch.

• Yuma County applications qualify for 6 mitigation relief points.

• If more points are required, consult EPA’s Mitigation Menu website and consider using their Worksheet to ensure adequate points can be attained to use the pesticide. Mitigation points are based on several factors, field characteristics, participation in conservation programs, application parameters, and more.

 

Endangered Species Bulletins

• Is an Endangered Species Protection Bulletin required? Check the label under “Directions for Use.” If required, access the Bulletins Live! Two website. Enter or navigate to the application site using the map; select month and year of application; enter the product EPA Registration Number.

• Print bulletin. If a Pesticide Use Limitation Area (PULA) appears in the map view, click the colored area of the PULA to turn the red “Printable Bulletin” button green. Click the green button to download or print the bulletin.

• If your field(s) are located inside a Pesticide Use Limitation Area (PULA), follow the bulletin guidelines for limitations on pesticide use. If your fields are outside the PULA, follow label requirements and keep a copy of the bulletin for your records.

• PULAs in Yuma are found along the Colorado and Gila Rivers in production areas for certain Dicamba products. These require both a 310-foot in-field wind-directional spray drift buffer and a 57-foot omnidirectional in-field buffer for fields found within the PULA.

• Plan ahead. You can access and print Bulletins up to 6 months prior to an application. Consider entering registration numbers for the main pesticides in your program, then generate a bulletin for each month and year you expect to apply the pesticide. Keep these with your records in case an application is needed.

 

Want a Deep Dive on This?

There will be a Laws & Regulations CEU opportunity on September 3 in Yuma, where this topic will be covered in detail.

• 4 CA DPR L&Rs CEUs and 4 AZ CEUs (pending approval)
• This is a great chance to learn how to stay compliant and ask questions directly.

 

For more info, contact Dr. Al Fournier at Fournier@cals.arizona.edu

The Colorado River Compact of 1922 was formally negotiated among the basin states (Figure 1) to define how much water from the Colorado River can be used by each state on an annual basis. In 2007, basin states negotiated interim guidelines to deal with Colorado River water shortages and determine the reductions for each state depending on the elevation of water in Lake Mead. Another series of agreements have included Colorado River water allocations to Mexico.
 
After more than 20 years of drought, reduced flows in the Colorado River are now resulting in some serious steps to arrest the decline of the major storage reservoirs, Lakes Powell and Mead. The Drought Contingency Plan (DCP) Authorization Act was agreed to by the lower basin states (Nevada, California, and Arizona) and signed into law on 16 April 2019.  Participation from Mexico was determined through a U.S. – Mexico agreement.  The DCP outlines a process, dependent upon triggers related to the water level in Lake Mead that is intended to protect the Colorado River system through voluntary reductions and increased conservation. Similarly, there is an Upper Basin DCP involving Colorado, New Mexico, Utah, and Wyoming.  The lower basin DCP will extend through the end of 2026 and consists of increasing reductions in Colorado River use in Tiers 1, 2a, 2b, and 3 at Lake Mead elevation levels of 1,075; 1,050; 1,045; and 1,025 ft. above sea level, respectively.
 
With the water level in Lake Mead below 1,075 ft. above sea level, the Tier 1 water allocation reductions have been called into action by the Bureau of Reclamation beginning in January 2022.  
Arizona will suffer the biggest cuts because it agreed in the 1960s to take the lowest priority among the Lower Basin states.  According to the DCP, Tier 1 requires a 512,000 acre-foot (AF) reduction in Arizona’s 2.8M AF annual allocation.  This reduction is primarily being taken from the agricultural irrigation districts associated with the Central Arizona Project (CAP), primarily impacting agricultural areas in Pinal County.  It is important to note that urban/metropolitan and tribal water allocations are not reduced in Tier 1 conditions.
 
Even with the DCP reductions, there are still valid concerns regarding the rate of decline of Lakes Mead and Powell with a continuation of existing weather patterns.  As a result, representatives from Nevada, California, and Arizona have been working on an additional plan to provide further reductions of water use from the Colorado River with a goal of achieving an additional 500,000 AF to leave in Lake Mead.  This would serve to nearly double the conservation of Colorado River water and further reduce the rate of decline in Lake Mead.  For California, this would mean they will take water reductions prior to reaching DCP levels that would trigger their mandatory cuts.
 
This new proposal is being referred to as the “500+ Plan” and it would be entirely voluntary among entities in the lower basin states to participate.  It is estimated that $100M will be needed to implement this plan for further reductions in Colorado River water allocations from the three lower basin states.  For example, this plan would include payments to farmers for fallowing land to save water.  The water agencies from these three states are working to find the money to support this effort and Arizona has pledged $40M to support the plan.  California and Nevada have the plan under review for funding and additional funding could possibly come from the federal government to make this work.
 
In the past two decades, the flow of water in the Colorado River has declined nearly 20% below the 20th century average.  As a result, extractions from the Colorado River have exceeded inputs and in time this catches up with us.  These plans are important for everyone living in the desert Southwest with a dependence on the Colorado River.  Therefore, all steps to conserve this valuable source of water are critical.  In Arizona, approximately 70% of the water is diverted to agriculture and our efforts to provide good stewardship and management of our water resources are always important and increasingly so under these circumstances.
 
Reference:
Colorado River Drought Contingency Plan: Arizona Implementation. Central Arizona Project
https://library.cap-az.com/documents/departments/planning/colorado-river-programs/CAP-FactSheet-DCP.pdf

Figure1. The Colorado River watershed of seven western U.S. states and 2 Mexican states.  Source: USGS.

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 ‘Meerkat’ was seeded, then sprinkler-irrigated to germinate seed Jan 13, 2025 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 CO₂ backpack sprayer that delivered 50 gal/acre at 40 psi to flat-fan nozzles.

Downy mildew (caused by Peronospora farinosa f. sp. spinaciae)was first observed in plots on Mar 5 and final reading was taken on March 6 and March 7, 2025. 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-ft²areas within each of the four replicate plots per treatment.  The number of spinach leaves in a 1-ft²area of bed was approximately 144. The percentage were then changed to 1-10scale, with 1 being 10% infection and 10 being 100% infection.

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 most effective control against the disease include Orondis ultra, Zampro, Stargus, Cevya, Eject .Please see table for other treatments with significant disease suppression/control.  No phytotoxicity was observed in any of the treatments in this trial.

Yesterday, we initiated our first trial of the season examining the use of band-steam for controlling Fusarium wilt of lettuce. The premise behind this research is to use steam heat to raise soil temperatures to levels sufficient to kill soilborne pathogens. For Fusarium oxysporum f. sp. lactucae, the pathogen which causes Fusarium wilt of lettuce, the required temperature for control is generally taken to be > 140°F for 20 minutes.

In our multi-year study, we are using a 35 BHP steam generator mounted on a custom designed elongated bed shaper to inject steam in the soil (Fig. 1). Trials conducted last fall show the technique holds promise. Fusarium colony forming units (CFU) were reduced from 2,600 in the control to 155 in the 0.75 mph travel speed and 53 in the 0.5 mph travel speed treatments, respectively (Fig. 2).

Fusarium load at the site where this week’s trial was conducted is reportedly high and we’re looking forward to obtaining good results. We’re also planning a second trial later this month at the Yuma Ag Center that is also focused on Fusarium wilt of lettuce control.

Stay tuned for results of all our trials examining the efficacy of using steam heat to control Fusarium wilt of lettuce, sclerotinia lettuce drop, pythium and weeds.

As always, if you are interested in seeing the machine operate or would like more information, please contact me.

Acknowledgements
This project is sponsored by USDA-NIFA and the Arizona Specialty Crop Block Grant Program. We greatly appreciate their support. A special thank you is extended to Larry Ott and Gila Valley Farms for allowing us to conduct this research on their farm. Fig. 1. Prototype band-steam applicator/bed shaper operating in Wellton, AZ. Fig. 2. Effect of band-steam applied at two travel speeds on Fusarium colony forming units (CFU) in the soil.

Fig. 1. Prototype band-steam applicator/bed shaper operating in Wellton, AZ.


Fig. 2. Effect of band-steam applied at two travel speeds on Fusarium colony
forming units (CFU) in the soil.

Malva (malva parviflora) is one of the oldest and most pervasive weeds that that we deal with here. It is also known as little mallow or cheeseweed and is in the same family as cotton, okra and hibiscus. It is often classified as a winter annual but survives all year in this region. It has a deep taproot and can grow in compacted clay or sand and in freezing conditions and high temperatures It provides a refuge for insects and diseases that can damage several crops.

Malva is easy to identify both as a seedling and mature plant. The seedlings are distinctively  heart shaped and the mature plant is broad and palm shaped. It is very vegetative and can grow to 6 ft.

The deep tap root of this weed makes it difficult to cut out after it is established. Its response to herbicides id somewhat unusual. It is very sensitive to contact herbicides that do not move into the plant. These include Goal, Sharpen Gramoxone , Rely,Aim and others. However, it is not sensitive to systemic herbicides like 2,4-D and Glyphosate. It reproduces from seed and can be controlled preemergence with many of the same preemergence herbicides used in cotton like Prowl or Treflan. The seed pods are wheel shaped which is where the name cheeseweed comes from. Each seed pod contains 10 to 12 seeds

Area wide Insect Trapping Network   VegIPM Update, Vol. 15, No. 17, Aug 21, 2024
 
Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:           
CEW moth counts decreased areawide; about average to previous years.
 
Beet armyworm:         
BAW moth counts are up in south Yuma valley and Dome valley; about average for August

Cabbage looper:           
Cabbage looper numbers are low consistent with previous years and higher temperatures.
 
Diamondback moth:      
DBM moths were not caught in any trap; average for this time of the year.
 
Whitefly:                      
Adult movement continues to decrease, average for this time of the year.
 
Thrips:                          
Thrips adult activity continues to decline, average for August.
 
Aphids:                       
Aphid movement is absent and consistent with what we typically see during the summer.
 
Leafminers:                  
Adult activity declining and average for August.