Editor’s note: Iowa State University Extension weed specialist Bob Hartzler summarizes the high points of the recent reregistration of over-the-top dicamba products and the new rules that come with the new five-year labels. It is by no means all inclusive. Links to three product labels are included at the bottom.
Most people are aware that Environmental Protection Agency approved new labels for the dicamba products used on dicamba-resistant crops. The following describes major changes in the labels and important restrictions. The labels only describe use on the dicamba-resistant crops, therefore eliminating some of the confusion on earlier labels.
Major changes to dicamba use on dicamba-resistant soybean
• Must use volatility-reduction agent.
• Apply before June 30 or up to R1 stage, whichever comes first. The Engenia label doesn’t have the R1 cutoff, so in some situations Engenia could be applied later in the season than Xtendimax.
• Always maintain a 240-foot buffer between last treated row and downwind field edge (roads, mowed grass, tolerant crops can be included in the buffer). The previous label required a 110-foot buffer at 22 ounces and a 220-foot buffer at 44 ounces. The 44-ounce rate has been eliminated from the label.
• Apply only one hour after sunrise through two hours before sunset.
• Apply when wind speed at boom height is between 3 and 10 mph.
• Do not apply during temperature inversions.
• Do not apply product if sensitive crops or certain plants are in an adjacent downwind field.
• Do not apply if rain is expected in next 48 hours that may result in runoff.
• Maximum boom height of 24 inches, maximum ground speed of 15 mph.
• Dicamba-specific training still required.
• 57-foot omni-directional buffer required in counties with endangered species (In Iowa, Hardin County and several counties in NE IA are affected by this).
This list isn’t comprehensive, just a quick summary of the label. I assume other products will have similar restrictions.
Bayer Xtendimax w/VGT label
Syngenta Tavium Plus Vapor Grip