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Frequently asked questions about dicamba herbicides

Tom J. Bechman young corn field
DICAMBA CUTOFF FOR CORN: You can’t spray restricted-use dicamba pesticides in corn in Indiana after June 20.
Here’s what you need to know about all dicamba herbicides in Indiana in 2021.

If you plan to spray any agricultural dicamba product in Indiana, check out answers to “frequently asked questions” posted by the Office of the Indiana State Chemist. It’s not business as usual if you’re spraying any dicamba ag herbicide.

In an earlier article, What you should know about spraying dicamba in 2021, Bill Johnson, Purdue University Extension weed control specialist, highlighted that the cutoff date in Indiana for spraying dicamba soybean herbicides is June 20, and offered several good reasons why you would likely make your application before that date anyway.

“We’ve provided information on our website that spells out exactly which dicamba products are affected, and when they can’t be sprayed this summer,” says Dave Scott, pesticide administrator for the office. “The Indiana Pesticide Review Board [IPRB] determined dicamba to be a highly volatile herbicide, as defined by state law. That’s why there are changes.”

Find a full list of questions and answers at Purdue Extension.

Frequently asked questions

The Office of the Indiana State Chemist answers common questions about dicamba:

Which herbicides were classified as “highly volatile herbicides” by the IPRB? All Restricted Use Pesticides containing more than 6.5% dicamba are classified as HVH herbicides. An HVH is defined in state law as any herbicide capable of emitting vapors that may cause serious injury to desired plants by reason of movement of the vapors from the area of application of the herbicide to areas inhabited by the desired plants.

Is there a list of these herbicides? Yes. See this list of currently registered dicamba RUPs. The list of HVHs does not include low level dicamba herbicides that are routinely labeled for use on turf and in lawn and landscape settings. However, it does include products like Banvel and Status used in corn, and dicamba pasture herbicides.

Are there restrictions on when HVHs can be applied? Yes. First, the use of HVHs must comply with any application timing restrictions listed on the label of the product being used. In addition, HVHs may not be applied during the period from June 21 through Aug. 31. Application of an HVH during that no-spray period will constitute a violation of Indiana law, specifically IC 15-16-4-59(5).

Does the no-spray period apply to all HVHs and all target crops, or just to Engenia, Tavium and XtendiMax on soybeans? The no-spray application restriction applies to all dicamba HVHs, regardless of the target crop or site to which it is being applied. The IPRB determined that all currently registered agricultural dicamba herbicides are capable of emitting vapors from the area of application of the herbicide to areas inhabited by desired plants. Therefore, the permit requirements, including the restricted application dates, apply to all dicamba HVHs and all target application sites.

The general permit states that all certified and licensed agricultural applicators are covered by the permit to apply HVHs. Does that allow for someone without a license, spraying under the supervision of a certified and licensed applicator under state supervision rules? The labels for Engenia, Tavium, and XtendiMax require all users to be fully certified and licensed. So, direct supervision of noncertified applicators is not allowed for those products. However, for all other state RUP dicamba HVHs, the law and the general permit still allow legal use of those products by noncertified applicators being supervised by certified and licensed applicators.

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