By Ahmit Jhala, Extension Weed Management Specialist

I recently received several phone calls from growers with questions on terminating broadleaf cover crop species and broadleaf weeds using dicamba products. The growers were particularly interested in whether dicamba products such as Banvel, Clarity, and DiFlexx could be applied to terminate broadleaf cover crop species such as hairy vetch, field peas, or mixtures and broadleaf weeds such as henbit, field pennycress, or marestail immediately before planting soybean. The answer for the dicamba-based herbicides listed above is NO. This is because their labels have soybean planting intervals of 14 to 60 days, depending on the product and its use rates.

  • For example, for Clarity to be applied at 16.0 fl oz/acre, there would be a 28-day soybean planting interval after one inch of rain. If Clarity were to be applied at 8.0 fl oz/acre, the soybean planting interval would be 14 days after one inch of rain. The Clarity label also specifies: “Do NOT make Clarity burndown applications to soybeans in geographic areas with average annual rainfall less than 25 inches.”
  • If DiFlexx is applied burndown at 24 fl oz/acre or less, the planting interval for soybean is 60 days.

This longer planting interval must be applied because Roundup Ready 2 Xtend soybean is not listed on Banvel, Clarity, DiFlexx, or other dicamba products.

Dicamba-resistant soybean, also known as Roundup Ready 2 Xtend soybean, became available commercially in 2017. Three dicamba products (FeXapan, Engenia, XtendiMax) are labeled to be applied pre-plant, pre-emergence, or post-emergence (up to R1 soybean growth stage) for broadleaf weed control in Xtend soybean.

Take Home Message

  • You can use dicamba products such as FeXapan, Engenia, or XtendiMax as per label requirements in a burndown application and plant Roundup Ready 2 Xtend soybean without a planting interval.
  • You can NOT use dicamba products such as Banvel, Clarity, and DiFlexx, and immediately plantRoundup Ready 2 Xtend soybean. If you use these products, you have to maintain a soybean planting interval of 14 to 60 days, depending on the product and its use rates. Read the label. 
  • We recommend NOT using any dicamba product for spring burndown application before planting Roundup Ready soybean, Liberty Link soybean, and conventional/organic soybean.