Even if you are planting RR2 Xtend® soybeans, the answer to this could be “I’m undecided.” Some growers are planting RR2 Xtend® soybeans in 2017 and using their existing herbicide plan without dicamba. These growers are willing to let first year experiences improve their knowledge base for dicamba use in 2018. However, there are good reasons to use dicamba in a preplant or postemergence program. The increasing spread of herbicide-resistant weeds have lowered the performance of many herbicide programs.
Consider some of the following before integrating dicamba into your Xtend® soybean system:
- Be sure to read and understand the dicamba labels and stewardship guidelines. Assess fields now to determine if some should not be treated with dicamba due to sensitive surroundings. Other fields may be at risk from frequent wind direction on the day of application.
- While we use the term “dicamba” throughout this discussion, only three dicamba products are labeled for use in Xtend soybeans: XtendiMax, FeXapan, and Engenia. Use of other dicamba products is an off-label application.
- Some growers will be planting non-Xtend and Xtend soybeans. If dicamba use is a planned program, ensure that planters are cleaned out before switching seed traits and dicamba is applied to the right fields.
- Each of the labeled dicamba choices have frequently updated websites listing new approved tank mixes, adjuvants and nozzles. You are required to check the label within 7 days of application for any changes or updates.
- If you’re planning to use a custom applicator for dicamba applications, be aware that some will not be spraying dicamba on soybeans this year. Other applicators may have higher rates for dicamba use.
- Consider your weed spectrum and compare weed control ratings between dicamba and your current herbicide choices. Also, acknowledge weed resistance to certain herbicide groups in your area. Dicamba has excellent control ratings for marestail, giant ragweed, and waterhemp.
- Your current herbicide program may be effective. However, using dicamba could reduce the selection pressure for resistance to certain herbicides due to their continuous use or overuse. An example of this is the reliance on HG14 herbicides (Valor, Flexstar, Cobra/Phoenix) for weeds that are resistant to glyphosate and ALS inhibitors. Continued use of HG14’s is pushing weeds to become resistant to 32 herbicides used in corn and soybeans. Substituting dicamba for fomesafen or Cobra in the postemergence treatment can sustain many of the other HG14’s.
- Dicamba may be more cost effective versus postemergence combinations of glyphosate + fomesafen (Flexstar etc.).
- Dicamba can be a better and more consistent herbicide in preplant burndown. There are no plant back restrictions if your using an approved dicamba on Xtend soybeans.
- Keep in mind that failure to use any new technology judiciously can result in selection for resistance and possibly reduce their utility rapidly.