New broad-spectrum herbicide for rice weeds gets name: Loyant

“There are a few things coming from industry that are going to make weed control interesting,” says Hunter Perry, field R&D scientist for Dow AgroSciences. “We are excited about Loyant because it has robust activity on a variety of weeds – grasses, sedges and broadleaves – and because of the resistance aspect.”

​Rinskor active attracted a lot of discussion when it was mentioned along with several other new herbicide active ingredients for weed control in rice at the Roy J. Smith Barnyardgrass Workshop in Stuttgart, Ark., last spring.

Now that Dow AgroSciences has given it a commercial name – Loyant – it’s likely to attract even more discussion as it winds its way through the registration process at EPA over the next two years, according to DAS specialists.

“There are a few things coming from industry that are going to make weed control interesting,” says Hunter Perry, field R&D scientist for Dow AgroSciences. “We are excited about Loyant because it has robust activity on a variety of weeds – grasses, sedges and broadleaves – and because of the resistance aspect.”

Dr. Perry said many of the susceptible weeds Loyant will control also have a resistant counterpart, such as barnyardgrass. “It has developed resistance to multiple modes of action as has flatsedge and other weeds. Loyant has controlled those resistant biotypes of those weeds so it’s exciting to have a new herbicide coming that can perform that way.”

Some biotypes of barnyardgrass are resistant to ALS inhibitors, some to propanil and some to quinclorac or Facet. “There are a few biotypes out there that are resistant to Clincher herbicide, but those are few compared to the others,” says Perry.

Rotate modes of action, crops

“So, basically, weed scientists across the Mid-South are recommending you tank mix and rotate modes of action as much as possible. Rotate crops, as well. Rice and soybeans in rotation would allow you to use a couple of new modes of action in there to allow you to pick up barnyardgrass between the rice growing seasons. It can be done, but the populations that are developing resistance to multiple modes of action are becoming more difficult to control.”

As a result, weed control is becoming more expensive for those growers at a time when profit margins don’t allow for additional expense. Growers are having to burn down with one group of herbicides, apply pre-emergence herbicides and then spray multiple modes of action pre-flood and hope they don’t have to come back with a post-flood application.

Having worked closely with Loyant in its early stages of development, Jason Norsworthy, a University of Arkansas professor of weed science, says farmers need a new solution to the multiple resistant barnyardgrass issues they face.

“It’s not uncommon to find resistance to ALS herbicides, propanil and quinclorac within the same field. In these cases, there are not many options left, and that’s why there’s a lot of talk and excitement around new chemistry,” he says. “We’ve done greenhouse work that demonstrates Loyant is very active on quinclorac-, propanil- and ALS-resistant barnyardgrass.”

Besides barnyardgrass, Loyant will provide control of ALS-resistant rice flatsedge, smallflower umbrellasedge, and it has activity on the ALS-resistant yellow nutsedge. “It’s an excellent material for control of aquatic weeds, many of which are ALS-resistant,” says Dr. Norsworthy. “I think it has a very strong play with common resistant weeds in rice.”

Wide window of application

Loyant can be applied from two-leaf rice to late boot stage, says Dow AgroScience’s Perry. “Weed sizes will be dependent on the weed species. It will control tillered barnyardgrass; up to 8-inch in height broadleaves; and up to 4- to 5-inch sedges.”

As for application timing, Loyant can be applied pre-flood or post-flood. “Loyant can perform very well pre-flood before putting a permanent flood on the field,” says Perry. “Just like most post-flood applications with other herbicides, you want to bring the water down to expose at least 70 percent of the weed so that when you do spray, you’re getting good herbicide coverage.”

The Loyant formulation will have a low use rate and low adjuvant requirement. Loyant herbicide is expected to offer excellent crop safety and fit well in Clearfield and conventional rice systems.

“Dow AgroSciences is committed to providing rice growers the ability to produce clean fields today and protect their future yield,” says Perry. “We are excited for the addition of Loyant herbicide, which will help to broaden our existing strength on rice weed control.”

Research indicates Loyant’s broad spectrum of control will include:

Grasses – Barnyardgrass, broadleaf signalgrass, junglerice and suppression of tighthead sprangletop;

Broadleaves – Hemp sesbania, pigweed, jointvetch, eclipta, dayflower, ducksalad, grassy arrowleaf, redstem and numerous other broadleaf weeds;

Sedges – Yellow nutsedge, smallflower umbrella sedge and rice flatsedge.

Because Loyant has minimal residual herbicide activity on grasses, Perry says growers should consider tank-mixing Loyant with a residual herbicide when there is significant delay between application and flooding.

“The closer you get to establishing the permanent flood, the less important the addition of a residual herbicide may be because the floodwater should help prevent the next flush of weeds from emerging,” he noted.

For more information on Loyant, visit

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.