Dicamba Update: FMC on Tank-Mix Partners, Nozzle Selection, and Concerns About a Late Spring

Editor’s note: Last week, FMC announced three more herbicides — Authority Supreme, Spartan 4F, and Spartan Charge — have been added to the XtendiMax herbicide with VaporGrip Technology website page and to the Engenia herbicide website page as approved tank-mix partners. CropLife Field Editor Matthew J. Grassi caught up with FMC Regional Technical Service Manager Gail Stratman to learn more about what this latest news means for applicators.


CL: What is the impact of these tank-mix partners?

Dicamba Update: FMC on Tank-Mix Partners, Nozzle Selection, and Concerns About a Late Spring

Gail Stratman

These tank-mix options from FMC provide growers with effective tools to manage difficult weeds and help protect dicamba technologies from resistance selection by reducing the need for multiple in-season applications to control later flushes of emerging weeds.

For example, Authority Supreme herbicide is an excellent foundation herbicide for a number of different herbicide-tolerant crop systems including: Roundup Xtend, Enlist, and LibertyLink. It combines the newest Group 15 herbicide along with the longest residual Group 14 herbicide for a powerful residual combination.

CL: Are there any best practices on handling/mixing these newly approved FMC herbicides with the dicamba herbicides?

Nothing additional is required. These FMC products have been cleared for use because they have been shown not to cause adverse effects and do not increase drift or volatility when tank mixed with these dicamba herbicides.

CL: How important is nozzle selection in this system?

It’s extremely important to use the proper nozzles for dicamba tank-mix applications to minimize drift potential and maximize efficacy through proper spray coverage. There are no additional requirements for the FMC tank-mix partners. Just follow what is on the label for the dicamba product you are using.

CL: Now that FMC is fully approved to “ride along” with XtendiMax or Engenia in the tank, any thoughts from FMC on how we need to deploy this tool sustainably so that we don’t lose it to resistance?

A good pre- and post-herbicide program is the best way to curb and manage resistant weed populations. We must deploy a strong pre-emergent herbicide program with multiple modes of action that target a broad spectrum of weeds, like the Authority brand herbicides. That way we don’t rely on dicamba as the primary weed control tactic and increase the selection pressure for resistant weeds. We need to start clean, always use dicamba in tank mixes, apply when weeds are small, and don’t rely on a single mode of action. Traits should not change the way we control weeds.

CL: What concerns do you have about weather this spring?

If we have a late spring, farmers may abandon their pre-emergence or planting-time herbicide applications. That means more weeds will emerge and be subjected to selection pressure for post-herbicides like dicamba. Pre-emergence herbicide applications have to take a higher priority than in the past. With higher levels and greater frequency of resistant weeds, some of the tools we relied on are no longer viable. Executing a strong pre- and post-herbicide program has never been more critical for optimizing yields.

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