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Focus on Soybean Webcast--Spray Drift

The current production environment of herbicide-resistant (HR) weeds, HR crops, and new herbicide technologies has resulted in increased incidence of damaging offsite herbicide movement and the subsequent need to mitigate this negative aspect of herbicide use and application. The mitigation of this offsite drift is necessary to ensure the longevity of current and forthcoming new weed control tools.

The Nov. 29, 2018 issue of PMN Update (Issue 190) provides the link to a webcast that provides timely information about this subject for soybean producers.

The “Focus on Soybean” webcast, titled “Minimizing Herbicide Drift”, is presented by Dr. Travis Legleiter, Extension Assistant Professor of Weed Science at the University of Kentucky, Princeton.

In this presentation, Dr. Legleiter hones in on application and environmental factors that are known to enhance physical (non-vapor) herbicide drift, and how these factors can be avoided (uncontrollable factors) or modified (controllable factors). Highlights from the presentation follow.

•   Influencers of drift (physical or droplet drift), both those outside of producer control [weather (wind speed, air temperature and humidity, air stability/inversions)] and those within producer control (droplet size, height of spray release above the crop canopy, time of spraying, nozzle pressure and type) are discussed.

•   Class of droplet size (< 200µm most subject to drift) and its relation to drift potential are thoroughly examined and evaluated.

•   Types of nozzles needed to create consistent droplet size are shown schematically (two-stage-with-air-induction nozzles preferred), with a detailed description of how they work to reduce drift.

•   How boom height contributes to drift by controlling the time droplets are in the air.

•   Slower sprayer travel speeds (usually <15 mph) needed to prevent vortexes behind the sprayer.

•   Buffer strips to contain movement of spray particles within the target field.

This presentation is very timely since it coincides with the recent re-registration of dicamba herbicides. Even though producers are already keenly aware of the need to control offsite movement of all herbicides, this narrated presentation provides a very concise video summary of the factors contributing to this process, and the tools they can use (especially nozzle types) to reduce the likelihood of offsite drift of herbicides during application.

Composed by Larry G. Heatherly, Nov. 2018,