If you can’t use dicamba on dicamba-resistant soybeans, what are the alternatives?
Tom Peters, North Dakota State University and University of Minnesota Extension sugarbeet weed specialist; and Joe Ikley, NDSU Extension weed specialist, suggest several different products to control the following weeds:
Waterhemp. It is safe to assume that any waterhemp is resistant to ALS-inhibiting (Group 2) herbicides. Glyphosate resistance is also present on most acres, though not all plants will be resistant.
Glyphosate is most effective on waterhemp up to two leaves when applied at labeled rates with adjuvants. The best remaining options would be PPO-inhibiting (Group 14) herbicides. Flexstar (fomesafen), Cobra, or Ultra Blazer could all be used on small waterhemp. The addition of oil adjuvants will be important for weed control.
Flexstar cannot be applied after June 20th west of Highway 281.
Common lambsquarter. Glyphosate has historically provided variable control of common lambsquarter. Harmony (thifensulfuron) will be one of the best options left for the Xtend acres.
Kochia. Glyphosate is the best option for those who do not have glyphosate-resistant kochia. For the acres with glyphosate resistance, Flexstar is one of the few remaining options and must be applied to small plants. Flexstar will work best by maximizing spray coverage and using full rates of oil adjuvants.
Common ragweed. Glyphosate, FirstRate and Flexstar are the best remaining options for common ragweed control. North Dakota has several populations resistant to glyphosate and FirstRate, so do not expect control with either product on those populations.
Horseweed (marestail). The safe assumption for horseweed is that it is glyphosate resistant. This leaves FirstRate as the best remaining option. However, we do have some populations that are also resistant to FirstRate. Unfortunately, we are left with no effective postemergence options in Xtend soybean for horseweed populations that are resistant to both glyphosate and FirstRate.Source: NDSU, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.