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

Chile (Capsicum annuum) is an important crop in the desert Southwest. The Capsicum annuum species is the most common group of chiles that we encounter and these chiles are common in our southwestern diet. The New Mexico type chile (aka, Anaheim) is the most common type of chile crop in the desert Southwest including production ares in southeastern Arizona, southern New Mexico, west Texas, and northern Chihuahua, Mexico.

There are five domesticated species of chile peppers. 1) Capsicum annuum is probably the most common to us and it includes many common varieties such as bell peppers, wax, cayenne, jalapeños, Thai peppers, chiltepin, and all forms of New Mexico chile. 2) Capsicum frutescens includes malagueta, tabasco, piri piri, and Malawian Kambuzi. 3) Capsicum chinense includes what many consider the hottest peppers such as the naga, habanero, Datil, and Scotch bonnet. 4) Capsicum pubescens includes the South American rocoto peppers. 5) Capsicum baccatum includes the South American aji peppers (Guzman and Bosland, 2017). Some examples are shown in Figure 1 and some other chile pepper species as well.

Figure 1. Capsicum annuum pod types include A) Asian, B) Cayenne, C) Chile de Arbol,
D) Chiltepin, E) Hungarian Paprika, F) Jalapeño, G) New Mexican, and H) Poblano. A
Capsicum baccatum pod type is I) Aji. Capsicum chinense pod types are J) Bhut Jolokia,
K) Habanero, and L) Scorpion. A Capsicum pubescens pod type is M) Rocoto and a
Capsicum frutescens pod type is N) Tabasco. Source: Guzman and Bosland, 2017.

Crop Phenology
Understanding of the basic stages of plant growth in relation to time or age (crop phenology) and basic crop needs, i.e., water and nutrients, is an important part of crop management. There is a strong relationship among the phenological, morphological and physiological changes that occur with crop development. Understanding what is going on physiologically within a plant at various stages of growth and development is critical in efficiently managing crop inputs such as water and plant nutrients.

Plants respond to environmental conditions and temperature is the primary developmental force in plant development when water is not limiting. Heat units (HUs) can be used as a good measure of “thermal time” that drives plant development. Thus, HUs can be used as a management tool for predicting and identifying stages of growth and physiological needs. We can then use that information for more efficient timing of irrigation and nutrient inputs to crop and pest management strategies. Figures 2 and 3 describe the basic HU concept with upper and lower thresholds.

Crop phenology models describe how crop growth and development are impacted by weather and climate and provide an effective way to standardize crop growth and development among different years and across many locations (Baskerville and Emin, 1969; Brown, 1989).

People still use days after planting to estimate stages of crop development but HUs are more accurate and reliable. As a result, HU based methods of predicting and tracking crop growth can be more consistently and effectively used in crop production systems.

The use of HU-based phenology models is most applicable in irrigated crop production systems where water is a non-limiting factor. Water stress will alter phenological plant development and it is a major source of variation irrespective of temperature conditions.

Chiles are a warm season, perennial plant with an indeterminant growth habit that we grow and manage as an annual crop. The fruiting cycle begins at the crown stage of growth (Figures 4 and 5) and continues until the plant reaches a point of “cut-out” with a hiatus in blooming as the plant works to mature the chile fruit that the crop has set and established.

Figure 6 describes the basic phenological baseline for New Mexico – type chile and was developed from field studies conducted in New Mexico and Arizona (Silvertooth et al., 2010 and 2011; Soto et al., 2006; and Soto and Silvertooth, 2007).

Heat units accumulated after planting (HUAP) for any date of planting to the present date can be easily accessed in the Arizona Meteorological Network (AZMET) website.

https://azmet.arizona.edu/

In the 2025 season, New Mexico-type chiles in southeastern Arizona experienced a good start to the season after planting. In tracking a set of New Mexico-type chile varieties, their development is tracking very closely to the HU model shown in Figure 6. For example, crown formation and first flowers have been consistently observed at approximately 1,300 – 1,450 HUAP among numerous New Mexico type varieties in southeastern Arizona this season. Many fields are progressing through peak bloom consistent with Figure 6 and early set fruit is maturing nicely as well.

Figure 2. Typical relationship between the rate of plant growth and development and
temperature. Growth and development cease when temperatures decline below the
lower temperature threshold (A) or increase above the upper temperature threshold (C).
Growth and development increases rapidly when temperatures fall between the lower
and upper temperature thresholds (B).


Figure 3. Heat unit calculation with the sine curve method using upper and lower
temperature thresholds (Brown, 1989). The 86/55 ºF thresholds are used, consistent
with most warm season crops.

Figure 4. Photo of a New Mexico chile plant with crown formation and the first fruiting
branch shown withing the red circle.

Figure 5. Photo of a New Mexico chile plant with crown formation and early first fruiting
branch development. Source: Courtesy of Mr. Ed Curry, Pearce, AZ.


Figure 6. Basic phenological guideline for irrigated New Mexico-type chiles.

References
Baskerville, G.L. and P. Emin.  1969.  Rapid estimation of heat accumulation from maximum and minimum temperatures. Ecology 50:514-517.

Bosland, P.W., E.J. Votava, and E.M. Votava. 2012. Peppers: Vegetable and spice capsicums. Wallingford, U.K.: CAB Intl.

Brown, P. W.  1989. Heat units.  Bull. 8915, Univ. of Arizona Cooperative Extension, College of Ag., Tucson, AZ.

Guzmán, I. and P.W. Bosland. 2017. Sensory properties of chile pepper heat - and its importance to food quality and cultural preference. Appetite, 2017 Oct1;117:186-190. doi: 10.1016/j.appet.2017.06.026.

Silvertooth, J.C., P.W. Brown, and S. Walker. 2010. Crop Growth and Development for Irrigated Chile (Capsicum annuum). University of Arizona Cooperative Extension Bulletin No. AZ 1529

Silvertooth, J.C., P.W. Brown and S. Walker. 2011. Crop Growth and Development for Irrigated Chile (Capsicum annuum). New Mexico Chile Association, Report 32. New Mexico State University, College of Agriculture, Consumer and Environmental Science.

Soto-Ortiz, Roberto, J.C. Silvertooth, and A. Galadima. 2006.  Crop Phenology for Irrigated Chiles (Capsicumannuum L.) in Arizona and New Mexico. Vegetable Report, College of Agriculture and Life Sciences Report Series P-144, November, University of Arizona.

Soto-Ortiz, R. and J.C. Silvertooth.  2007. A Crop Phenology Model for Irrigated New Mexico Chile (Capsicum annuum L.) The 2007Vegetable Report. Jan 08:104-122.

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.

It is with sadness and a sense of loss that we share the news that our friend and colleague, John Palumbo passed away last weekend. John and I have been office mates so to speak, only two doors apart, for the past 17 years. What I will miss most about John is his presence. Warren Buffet said that a key to becoming a better person was to surround yourself with people that are better than you. In other words, hangout with people who had traits and characteristics that you admire and want to emulate. John was one of those people. He made you want to be a better person. We will miss you, John. RIP.

My name is Mazin Saber, and I serve as an Associate in Extension specializing in Weed Management at the School of Plant Sciences, University of Arizona/Yuma County Cooperative Extension, based at the Yuma Agricultural Center. My work focuses on developing innovative site-specific weed management strategies tailored to specialty crop systems in desert agriculture, aiming to establish effective and sustainable weed control programs. I currently lead a new weed control research initiative at the Yuma Agricultural Center.

My academic background includes a Bachelor’s degree in Agricultural Mechanization and a Master’s degree in Agronomy from the University of Basrah, Iraq. I also hold an M.E., and Ph.D. in Agricultural and Biological Engineering from the University of Florida, where my doctoral research focused on designing automated mechanical intra-row weed control system for row crops.

Previously, my research has involved quantitative assessment of crop water-use and salt balance in the Lower Colorado River region. By utilizing advanced tools such as Eddy Covariance to measure evapotranspiration across 14 major crops over multiple seasons on commercial farming, I have contributed to improving water use efficiency and enhancing the sustainability and competitiveness of desert agriculture.

As I build my weed management program, I am conducting an assessment survey to identify the most pressing weed management challenges. Your feedback is crucial to ensure this program meets your needs. Please take a few minutes to complete the survey using the link below.

https://uarizona.co1.qualtrics.com/jfe/form/SV_4Od09r4hPLThLz8

I am available for any discussions about weed issues on your farm and I am happy to arrange field visits or ride-alongs to better understand your specific challenges. Please feel free to reach out to me directly.

Email Mazin

To better support our stakeholders with pest management, we are launching an Insecticide Resistance Monitoring Program in Calvin’s Lab. This initiative will include seasonal insecticide efficacy bioassays using the most commonly used insecticides. We will target key pests of major crops grown in Arizona, with a particular focus on those affecting vegetables and citrus crops.

A major goal of this program is to establish baseline susceptibility data for Plinazolin’s target pests in vegetables and citrus crops. This will enable us to monitor potential changes in susceptibility over time and make informed, timely adjustments to pest control strategies.

Insecticide resistance monitoring is a critical component of Integrated Pest Management (IPM). Understanding the baseline susceptibility of insect pests is essential for early detection of resistance and the long-term success of new insecticide modes of action. It is especially important to gather this data for Plinazolin before its widespread adoption in our region.

To support this effort, we will collect insects from vegetable- and citrus-growing regions throughout Arizona. Your collaboration is essential. We will reach out to request access to field sites where we can collect target insect populations. Additionally, we encourage you to contact us directly if you experience insecticide control failures or suspect resistance in your fields.

Our current target pests include:

• Diamondback moth

• Beet armyworm

• Cabbage looper

• Western flower thrips

• Citrus thrips

• Aphids

• Whiteflies

 

Please let us know if there are additional pests you would like us to consider.

Thank you for your continued support. We look forward to working with you to address Arizona’s most pressing pest management challenges.

In Yuma's arid agricultural landscape, selecting the right cover crops can significantly influence soil health, water management, and overall sustainability. Two notable options gaining attention among growers are Sudan grass and Sesbania. Sudan grass, a warm-season annual grass, is widely valued in Yuma for its ability to rapidly establish, providing excellent soil protection against erosion and wind. Its extensive root system enhances soil structure, boosts organic matter, and improves moisture retention, crucial for subsequent crops grown in desert conditions. Sesbania, a fast-growing legume, offers additional benefits. It excels at fixing atmospheric nitrogen, naturally enriching the soil and reducing the need for synthetic nitrogen fertilizers. Its deep taproot system penetrates compacted soil layers, improving water infiltration and reducing salinity levels, a common challenge in Yuma's agriculture.

Which Cover Crop Should You Choose?
The decision between Sudan grass and Sesbania depends largely on specific farm goals and challenges. If rapid establishment, erosion control, and increased organic matter are primary concerns, Sudan grass is an excellent choice. However, if the goal is to address soil fertility, nitrogen fixation, and salinity issues, Sesbania may be more beneficial. Using either Sudan grass or Sesbania as a cover crop in Yuma promotes healthier soils and supports sustainable farming practices, benefiting growers economically and environmentally. Considering these cover crops can be a strategic move toward enhanced agricultural productivity and long-term soil health in the region.

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

 

Corn earworm: CEW moth counts remain at low levels in all areas, well below average for this time of year.

Beet armyworm: Trap increased areawide; above average compared to previous years.

Cabbage looper:  Cabbage looper counts decreased in all areas; below average for this time of season.

Diamondback moth: DBM moth counts decreased in most areas. About average for this time of the year.

Whitefly: Adult movement beginning at low levels, average for early spring.

Thrips: Thrips adult counts reached their peak for the season. Above average compared with previous years.

Aphids:  Aphid movement decreased in all areas; below average for late-March.

Leafminers: Adults remain low in most locations, below average for March.