By Jeremy Ross, Extension soybean agronomist, and Gus Lorenz, Nick Seiter, and Nick Bateman, Extension entomologists
Over the last few weeks there have been many questions about the legality of mixing insecticides with desiccants applied to soybean. There are several desiccants approved for soybean including Gramoxone, sodium chlorate, Aim 2EC, and Sharpen. There are no issues when mixing insecticides with Gramoxone, Aim 2EC, or Sharpen that we are aware of and the label does not prohibit mixing any insecticide with those products. However, a common practice is to mix Gramoxone with sodium chlorate. The sodium chlorate label specifically says “This product should not be mixed with insecticides or other organic materials, unless specifically recommended, because a fire or explosion may occur.”
While safety is the number one concern, according to the formulation specialist at Drexel, the only potential issues with fire or explosion hazards when mixing insecticides with sodium chlorate specifically refers to the mixing with organophosphate insecticides such as acephate. They have indicated there are no concerns when mixing with pyrethroid, neonicotinoid insecticides or combinations of the two. Additionally, the Arkansas State Plant Board has interpreted the label wording of “unless specifically recommended” as a legal recommendation in situations where insecticides are deemed necessary by practitioners such as University of Arkansas Agricultural Specialists, as long as they are not in the organophosphate class.
With recent outbreaks of Redbanded stink bug in Arkansas and the Midsouth and their ability to cause damage to soybean very late in the season, it is necessary to provide control measures commonly as late as desiccation timing. In situations where this occurs, it would be deemed a common and economically sound practice to mix certain insecticides with desiccants including sodium chlorate.