We’re excited to announce that the Proactive Resistance Management (PRM) app is officially live as of today! This tool has been many years in the making, with countless hours dedicated to reviewing and editing Arizona’s 1080 pesticide use data to ensure accuracy and reliability.

The PRM app translates community-scale pesticide use into easy-to-read charts that show temporal refuges—the periods when whiteflies are not exposed to a given mode of action. By visualizing these refuges, growers and PCAs can diversify chemistries, preserve susceptibility, and make more confident decisions for whitefly management across all crops.

If you’d like to learn more, or to schedule a tutorial on how to use the app with your farm or PCA team, please reach out to me.

To ensure the app is being used by the IPM decision makers—you must request access to use the app.

Request access here: http://PRM.extension.arizona.edu

Figure 1. Example temporal refuge chart from the Proactive Resistance Management
(PRM) web tool for a specific date and locality in Yuma, Arizona. Each colored bar
represents the proportion of temporal refuge (0–1) for a given Mode of Action (MoA) during
successive 90-day look-back periods. Higher refuge generally indicates fewer days of
exposure of whiteflies to that MoA, and thus lower resistance risk. These results are
interpretive, not prescriptive — refuge is one factor among many (including efficacy, crop
stage, and economics) that must guide product choice.

Click here to read more about the PRM app and learn how to put it to work in your fields.



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

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%). Lettuce was seeded, then sprinkler-irrigated to germinate seed on Nov 28, 2023 on double rows 12 in. apart on beds with 42 in. 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, which contained two 25 ft rows of lettuce. Plants were thinned Jan 17, 2024 at the 3-4 leaf stage to a 12-inch spacing. 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.

Powdery mildew (caused by Golovinomyces cichoracearum) efficacy trial treatments were made on January 27, 2025, February 12, 2025, and February 24, 2025, and disease was first seen on February 26,2024. Disease rating was done on March 19, 2025. Disease severity was determined by rating 10 plants within each of the four replicate plots per treatment using the following rating system: 0 = no powdery mildew present; 0.5 = one to a few very small powdery mildew colonies on bottom leaves; 1 = powdery mildew present on bottom leaves of plant; 2 = powdery mildew present on bottom leaves and lower wrapper leaves; 3 = powdery mildew present on bottom leaves and all wrapper leaves; 4 = powdery mildew present on bottom leaves, wrapper leaves, and cap leaf; 5 = powdery mildew present on entire plant. These ratings were transformed to percentage of leaves infected values before being statistically analyzed. Yield loss due to rejected lettuce heads would likely begin to occur on plants with a powdery mildew rating above 2.0 (percentage of leaves infected value of 40).

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. The most effective fungicides were Procure, sulfure(liquid), V6M-5-7, Luna sensation, Quintec and Merivon.

In previous articles (Vol. 11 (13), Vol. 11 (20), Vol. 11(24)), I’ve discussed using band-steam to control  plant diseases and weeds. Band-steaming is where steam is used to heat narrow strips of soil to temperature levels sufficient to kill soilborne pathogens and weed seed (>140 °F for > 20 minutes). The concept is showing good promise. This past season, three trials were conducted examining the efficacy of using steam for disease and weed control in Yuma, AZ. In the studies, steam was applied in a 4-inch-wide by 2-inch-deep band of soil centered on the seedline using a prototype band-steam applicator (Fig.1). The band-steam applicator is principally comprised of a 35 BHP steam generator mounted on top of an elongated bed shaper. The apparatus applies steam via shank injection and from cone shaped ports on top of the bed shaper. 
Trial results were very encouraging as the prototype applicator was able to raise soil temperatures to target levels (140°F for >20 minutes) at viable travels speeds of 0.75 mph. Steam provided better than 80% weed control and significantly lowered hand weeding time by more than 2 hours per acre (Table 1). Results also showed that Fusarium colony forming units (CFU) were reduced from 2,600 in the control to 155 in the 0.75 mph and 53 in the 0.5 mph treatments, respectively (a more than 15-fold reduction). A significant difference in Fusarium wilt of lettuce disease incidence was not found, however disease infection at the field site was low (< 2%) and differences were not expected. At 0.5 mph, fuel costs were calculated to be $238/acre which was considered reasonable and consistent with the values reported by Fennimore et al. (2014).

An unexpected finding was that plants in steam treated plots appeared to be healthier and more vigorous than untreated plots (Fig. 2). This trial is still in progress and it will be interesting to see if this improved early growth translates into increases in crop yield.
In summary, early trial results are showing good promise for use of band-steam as a non-herbicidal method of pest control. We plan on conducting further trials in this multi-year study. If you are interested in evaluating the device on your farm and being part of the study please contact me. We are particularly interested in fields with a known history of Fusarium wilt of lettuce and/or Sclerotinia lettuce drop that will be planted to iceberg or romaine lettuce.
As always, if you are interested in seeing the machine operate or would like more information, please feel free to contact me.

Acknowledgements
This work is supported by Crop Protection and Pest Management grant no. 2017-70006-27273/project accession no. 1014065 from the USDA National Institute of Food and Agriculture, the Arizona Specialty Crop Block Grant Program and the Arizona Iceberg Lettuce Research Council. We greatly appreciate their support. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.
A special thank you is extended to Mellon Farms for allowing us to conduct this research on their farm.

References
Fennimore, S.A., Martin, F.N., Miller, T.C., Broome, J.C., Dorn, N. and Greene, I. 2014. Evaluation of a mobile steam applicator for soil disinfestation in California strawberry. HortScience 49(12):1542-1549.

Click link below or picture to see the band-steam and co-product applicator in action! 

Weeds are one of the most visible of all agricultural pests. They can’t move or hide and once established often stick up over the crop. Just one weed in a 10 acre field is annoying to look at. With insects and diseases, the damage is often more visible than the pest. That is not the case with weeds. A moderate weed infestation is approximately 10 weeds per square foot. If a herbicide produces 90% control, that leaves 1 weed per square foot or 43 weeds per acre. Without an untreated check, this can look like the herbicide failed!  It is easy to leave an untreated spot in a field and it is well worth doing. Many applicators do so unintentionally because of skips, powerlines and other causes. They help determine crop injury and weed control. Here are some examples of what various levels of control looked like from one of our cole crop trials:

VegIPM Update Vol. 16, Num. 23

Nov. 12, 2025

Results of pheromone and sticky trap catches below!!

Corn earworm: CEW moth counts down in most traps over the last two weeks; about average for early November.

Beet armyworm: BAW counts increased across all locations, above average for early November.

Cabbage looper:Cabbage looper trap counts increased over the last two weeks. Overall, CL numbers this season have been higher compared to last year and above average for this time of the year.

Diamondback moth:Adult activity increased in a few locations; consistent with previous years.

Whitefly:Adult activity remains high in Welton area, for all other locations, about average for early November.

Thrips:Thrips adult activity slightly increased in a few locations; higher numbers compared to last year.

Aphids: Winged aphids continue to increase across most locations; about average for early November.

Leafminers: Adult activity continues to decrease in all areas, below average for this time of season.