Flexstar GT 3.5 is formulated to "combat weeds that are difficult to control with glyphosate alone or are resistant to glyphosate and ALS-inhibitors" (see fact sheet) with two active ingredients and two modes of action.
"Flexstar GT 3.5 is one of the few post-emerge products that has good activity on resistant weeds, such as waterhemp and giant ragweed," said Kevin Carlson, Federated's senior agronomist, adding that "it really needs to be set up with a good pre-emerge herbicide" (see article above).
Dale Hecht of Syngenta recommended Boundary® 6.5 EC herbicide as a solid pre-emerge herbicide choice to pair with Flexstar GT 3.5 post emerge to give "full season attention" (see fact sheet) to the most resistant weeds in soybeans. Boundary 6.5 EC (also with two modes of action) helps control early season grass and broadleaves, and also fits well in a resistance management program.
Boundary 6.5 EC followed by Flexstar GT 3.5 couples with the Liberty Link® soybean system to add both plant growth and yield potential. Hecht noted that adding 1 pt./ac. of Dual with the Flexstar GT 3.5 post application can further boost residual control.
Talk to your Federated Agronomist to learn more about pre- and post-emerge herbicide options for your soybean fields this year.