TAKEAWAY
A new tool provides guidance for optimalapplication of insecticides and other chemicals.
The toolkit can improve pesticide usefulness, lower costs, help manage pesticide resistance, protect pollinators and beneficial insects, and aid understanding of insecticide exposure to humans through the air.
Chemical insecticides can expose farm workers, rural homeowners, and others to toxins in the air, due to a process called volatilization. It happens when insecticide transfers from the leaf surface to a vapor in the atmosphere, due to light energy breaking down chemical bonds.
USU’s PesticideToolkit website is helping farmers understand and plan for that process. The toolkit can improve pesticide usefulness, lower costs, help manage pesticide resistance, protect pollinators and beneficial insects, and aid understanding of insecticide exposure to humans through the air.
Insecticides harm insects for only a certain amount of time after being applied. Over time, the concentration in the leaves of crops decreases. The change in concentration in leaves over time depends on several factors. Those include the nature of the insecticide but also weather conditions (such as air temperature, wind speed, light intensity, and cloud cover) and crop characteristics (such as the length of the leaves). Insecticide behavior varies because these factors change with field location, season, and time of day.
To account for the complex interactions of these factors, the publicly-available model can predict insecticide behavior under given meteorological and crop conditions.
We designed the website for use by growers, sprayers, bee managers, extension services, pesticide regulators, and scientists. Users enter an insecticide, crop, and insect of interest. They then access weather information for the current day or manually enter weather details. They can use default values for leaf and soil properties or select their own.
The website creates a graph showing the change in insecticide concentration over the next seven days. If toxicology data is available, it will also show how long it takes for concentrations to no longer be harmful to the insect of interest (whether that’s the targeted pest or a beneficial insect, like a pollinator).
This feedback helps farmers apply pesticides at the right time while avoiding potential negative health effects.
Table 3.F.1 Use cases for USU Pesticide Toolkit
| Farmers | Regulators | Researchers |
|---|---|---|
| Farmers can get a site- and condition-specific prediction of pesticide concentration after application. This can guide application timing based on the active ingredient of the pesticide. | Regulators can investigate recommendations for the preharvest interval (PHI), the re-entry interval (REI), and other timelines that are dependent on the rate of pesticide dissipation. | Researchers can assist with planning field work. The simulation of field work can guide decisions about sampling times as well as indicate conditions to record over the study. |
References
- Hageman, K. (2021). "Pesticide Toolkit". Utah State University Department of Chemistry and Biochemistry https://pesticidetoolkit.usu.edu/