Four extension weed specialists (from Purdue University, University of Illinois, and Ohio State University) have released a bulletin with five additional suggestions to reduce off-site movement of dicamba. This is in response to the EPA’s label for dicamba use that was released at the end of October.
In addition to the eight label restrictions the EPA detailed in its updated label for dicamba use, the bulletin provides five additional recommendations, citing, “one can do everything “per the label” but still have offsite movement.”
- Do not spray when the forecast indicates wind gusts will exceed 10 mile per hour. It is impossible to predict when a gust of this magnitude will happen nor how long it will last. Gusts that reach 30 mph can move spray particles and vapor for great distances.
- Reduce boom heights to the 24-inches above the target height limit specified on the label. Simply reducing the boom height from 48 to 24 inches has been shown to reduce the distance traveled by drift particles by 50%. One of the most effective ways to safely lower the boom height without running the boom into the ground is to reduce sprayer travel speed. Also remember that any travel speed over 15 mph is off-label. The labels also now recommend that travel speeds be reduced to 5 mph when making applications on the field edges.
- Avoid application when temperature exceeds 80 degrees. Assuming that these dicamba products have some potential for volatility, the risk of this occurring increases with temperature.
- Consider applying dicamba only preplant, preemergence, or very early postemergence. Over 90% of the offsite movement complaints resulted from postemergence applications. Our assumption is that applications earlier in spring will have less likelihood to cause problems even where dicamba moves, due to the absence in many cases of any developed vegetation to injure. Temperatures are also likely to be lower when applied preplant/preemergence versus postemergence, possibly reducing the risk of movement via volatility.
- Have conversations with neighbors to know what crops and technologies are being planted around Xtend soybean fields. Many offsite movement cases in 2018 occurred where neighbors planted Xtend and non-Xtend soybean adjacent to each other. Knowing what sensitive crops are in the vicinity of your Xtend fields will enable better decisionmaking about use of dicamba in a given field.