In a previous article, I stated that:

Herbicide-resistant (HR) weed populations are the product of intensive selection pressure resulting from the continuous use of a herbicide or herbicides with the same single mode of action (MOA). The most common example of this, of course, is the selection for glyphosate-resistant (GR) weeds that has resulted from continuous use of a glyphosate-only weed control program.

Selecting and using herbicides with different MOAs should be a primary tool used for preventing and/or managing weed resistance.

Knowing and using MOA categories should be an important component of a soybean weed control program to manage weeds that are resistant to herbicides that are now available.

Selecting herbicides with different MOAs must be combined with choosing herbicides within those MOA groups that are effective at controlling targeted weeds in individual fields.

There is ample documentation to verify that few if any new herbicides are coming to market. Instead, the near-future for soybean weed management falls into two categories:

Development of soybean varieties with new herbicide-resistance traits, and

Using available herbicides in combinations or in premixes that provide multiple MOAs.

Trivence, a new herbicide product from DuPont that can be applied preplant or preemergence to soybeans, provides burndown and residual control of broadleaf weeds. Its components provide three MOAs: ALS inhibitor (Group 2), PS-II inhibitor (Group 5), and PPO inhibitor (Group 14).

Active ingredients are chlorimuron ethyl, the active ingredient in Classic (Group 2), metribuzin, the active ingredient in Sencor (Group 5), and flumioxazin, the active ingredient in Valor (Group 14).

Depending on rate of application, Trivence herbicide controls an extensive list of broadleaf weeds, including several of the species that have developed resistance to both ALS- and EPSPS- inhibitor herbicides (Groups 2 and 9, respectively).

For best burndown results, the label states that 2,4-D should be added and is required for control of some weeds. The label also states that Trivence may be tankmixed with grass herbicides to control annual grasses.

Considering the multiple MOAs of this new herbicide mix, and its mixing capability with other broadleaf and grass herbicides, this product appears to be a valuable additional tool to use against HR weeds.

The rate of application to soils with a composite pH of greater than 7.0 is restricted. This will involve acreage in the Black Belt of Mississippi. Also, varietal sensitivity to metribuzin must be considered.

Refer to the Trivence label for the complete list of weeds controlled with particular rates, guidelines for tank-mixing with other herbicides, plant-back restrictions, specific stipulations for use by geography, and disposal.

This article neither promotes nor endorses this product for Midsouth soybean producers either alone or in contrast to other similar products. Rather, it is meant to inform you of something new that may be of value to you in your production system if you contend with or want to delay and/or prevent HR weeds in your operation.

Composed by Larry G. Heatherly, Apr. 2014, larryheatherly@bellsouth.net