Newly introduced Loyant offers new mode of action for troublesome weeds

loyant logoWith the introduction this season of Loyant with Rinskor Active from Corteva Agriscience, growers have a new mode of action to add to their weed-management toolbox, according to a news release.

This takes on more importance because of the growing problem of herbicide resistance in weeds. According to the International Survey of Herbicide Resistant Weeds, the Mid-South accounts for more than 90 of the 160 unique herbicide-resistance cases documented nationwide. Of those, 29 cases are found in rice.

Rinskor Active is Corteva’s brand name for florpyrauxifen-benzyl, the active ingredient in Loyant.

It controls a broad array of grasses, broadleaf, sedge and aquatic weeds and belongs to the Weed Science Society of America’s Group 4. Loyant also controls weeds resistant to other modes of action.

Arkansas rice consultant Brent Lassiter says resistance is common in his area of Northeast Arkansas, including documented cases of pigweed resistant to ALS, PPO and glyphosate herbicides.

“Resistance management is a big deal and something we’ve been dealing with for a long time,” Lassiter said in the release. “Pigweed is especially robust and adaptive to its climate. ALS resistance is increasingly a challenge for rice growers. ALS-resistant flatsedge is becoming a real issue, as is tough-to-control nutsedge, barnyardgrass and other grasses.”

Loyant brings a new class of chemistry, controlling ALS-, glyphosate-, ACCase-, PPO- and triazine-resistant biotypes as well as other Group 4-resistant weeds in rice, according to the release.

“Rinskor active, the new active ingredient in Loyant, has an alternative binding site from other Group 4 herbicides,” Ryan Miller, Mid-South market development specialist and new technology specialist for Corteva Agriscience, said in the release. “That means it is able to control not only susceptible species but also species with resistance to Group 4 herbicides such as quinclorac.”

The evolution of resistance has significantly increased rice production inputs and associated costs.

Barnyardgrass is one of the most troublesome weeds in rice. In Arkansas, researchers have identified biotypes resistant to both PSII inhibitors (ureas and amides) and synthetic auxins, or groups 7 and 4, respectively, according to WSSA information.

In Mississippi, researchers have found barnyardgrass populations resistant to four different modes of action: ACCase inhibitors, ALS inhibitors, PSII inhibitors and cellulose inhibitors. They belong to groups 1, 2, 7 and 26, respectively, according to WSSA.

University of Arkansas Extension research has found a heavy barnyardgrass infestation in rice can result in a yield reduction of 30 percent to complete crop loss. By rotating effective modes of action, growers can protect their yields while at the same time protecting currently registered products.

“Utilize multiple effective modes of action to prevent herbicide resistance and protect current technologies,” Miller says.