Indiana Soybeans: Dicamba – Wind Speeds and Label Restrictions

©Debra L Ferguson Stock Photography

©Debra L Ferguson Stock Photography

Now that we are in the middle of July and most herbicide applications in corn and soybean should have ended, we wanted to take a look back at June this year. Specifically, we wanted to look at the weather this past June with regards to the labels for Engenia, FeXapan, and Xtendimax.

Last year we used weather data from the Agronomy Center for Research and Education (ACRE) near West Lafayette to determine how many hours were available to legally apply these products. This year, we installed new weather stations at Throckmorton Purdue Agricultural Center (TPAC) in Lafayette.

A few improvements with our new weather stations are that we have the ability to measure for temperature inversions, and that we have our wind gauge placed 3 feet above the ground, which would be about the maximum boom height for a postemergence application of those three products.

As a reminder of some of the limitations on these product labels, we can only make applications when the wind speed is between 3 and 10 MPH, and the Office of the Indiana State Chemist (OISC) and herbicide registrants also include a wind gust over 10 MPH as a label violation.

Applications are prohibited during a temperature inversion, and applications can only be made between sunrise and sunset. We are also not supposed to make applications within 24 hours of a forecast rain event. Knowing that applicators were given the ability to use their preferred weather source for rainfall predictions, and the hit-and-miss nature of many of our rain events this year, we did not include the 24 hour restriction when we calculated spray hours this June.

To determine the legal hours in June for this year, we combined the weather station data with the rainfall events at TPAC and how often the farm (i.e. Pete) was able to get their commercial sprayer onto a field for any type of pesticide application. When we packaged everything together, there were 47 hours across the month of June to legally apply Engenia, FeXapan, and Xtendimax at TPAC this year.

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