Farmers and the agriculture industry can’t stand another year like 2017 in terms of off-target movement of herbicides, especially dicamba products, Bill Johnson says. The Purdue Extension weed control specialist contributed information about limiting off-site movement in the 2018 Ohio, Indiana and Illinois Weed Control Guide, available now.
Others contributing included Bryan Young and Joseph Ikley from Purdue; Mark Loux, Doug Doohan, Anthony Dobbels and Bryan Reed from Ohio State University; and Aaron Hager from the University of Illinois.
You can order the guide by calling 614-292-1607 or visiting [email protected]. Recommendations based on the label and additional recommendations for dicamba are presented on pages 137 through 140 in the guide.
Here is a summary of five key recommendations offered by weed scientists:
1. Don’t spray when weather forecasts indicate wind gusts will exceed 10 mph. Johnson recognizes that it’s impossible to predict when a wind gust of this magnitude will happen, or how long it will last. It’s a fact that gusts that reach 30 mph can move spray particles and vapor for great distances.
2. Reduce boom height as much as possible. This one is a big deal, Johnson says. Boom height is a major factor in determining how much particle drift can occur. Simply reducing boom height from 48 inches to 24 inches can reduce the distance traveled by particles by 50%. The maximum boom height specified on current labels is 24 inches.
Specialists say one of the safest ways to reduce boom height without running the boom into the ground is to reduce travel speed. Any travel speed over 15 mph is off-label for the new dicamba products, and label recommendations now call for reducing travel speed to 5 mph when applying on field edges.
3. Avoid application when temperature exceeds 80 degrees F. Odds of problems increase when you spray at temperatures above 80 degrees, Johnson says. The specialists conclude in the guide that “assuming that these dicamba products have some potential for volatility, the risk of this occurring increases with temperature.”
4. Consider applying dicamba only preplant or very early postemergence. The specialists believe that applications earlier in the spring are less likely to cause problems even if dicamba moves. Their data indicates that 90% of off-site movement complaints resulted from postemergence applications. There is less, if any, sensitive vegetation to injure early in the season. Temperatures are also likely to be lower when applied preplant, they note in the guide, “possibly reducing the risk of movement via volatility.”
5. Talk to your neighbors. Know what crops and technologies are being planted around Xtend soybean fields, Johnson says. If there are fields of tomatoes or organic crops in the vicinity, you certainly want to know about it. Many off-site movement cases in 2017 occurred when neighbors planted Xtend and non-Xtend soybeans next to each other.
Knowing what sensitive crops are in the area where you will apply dicamba products is part of your responsibility of using the product, the specialists note.