Dicamba-Resistant Soybeans

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

A number of fields have been planted with Xtend soybeans, but not necessarily with the intention of spraying dicamba. However, with the weather and all, some folks might consider using dicamba. Remember, only labeled formulations of dicamba can be applied to Xtend soybeans. Anyone who applies these products must have undergone training. If you have undergone training, be sure you go through the checklists to be sure you can meet all the criteria required for application. Application timing is from sunrise to sunset and do not apply if the wind is very still (this could indicate a temperature inversion). Apply if wind speed is between 3 and 10 mph. Do not apply the wind is blowing towards a susceptible crop. Maintain at least 110-foot buffer, and boom height cannot exceed 24 inches above crop canopy. MOREOVER, there are more restrictions, so refresh your training before you decide to spray.

The new formulations of dicamba were developed to reduce volatility, but the issue of volatility has not been eliminated. We know high temperatures can cause these products to volatilize. We saw volatility with these products when they were applied to wheat stubble and air temperatures were 95°F.

With more research and experience with these dicamba formulations, we will have a better understanding of off-target movement and can provide better guidance on their use in this region. However, until that time be cautious about their use. If you are considering use of dicamba be sure to read and follow the label, be sure the applicator has received the proper training, follow the guidelines, and most importantly use common sense. Do not just consider “can I spray it” but also give serious thought to “should I spray it”.