Syngenta has announced that the Envoke herbicide label has been amended to include fall/early winter application in cotton, providing a needed tool for effective residual control of glyphosate-resistant horseweed and most winter annuals.

“Providing growers with the tools they need to effectively control weeds, including those that are resistant to herbicides such as glyphosate, is a primary focus for Syngenta,” said Scott Hendrix, Syngenta cotton crop manager. “We are excited about this new addition to the Envoke label and are confident based on trial results it will greatly enhance weed management programs.”

Controlling tough winter weeds prior to germination or while they are small is imperative in preventing weed competition and crop yield loss.

“Fall applications are going to be one of the more consistent ways of controlling horseweed,” said Larry Steckel, University of Tennessee Extension weed scientist. “Trying to burn down large horseweed that got its start the summer of the previous year or early in the fall is going to be hard with anything. If a grower catches these populations early with a residual herbicide, he is going to be way ahead of the game.”

Applied at the low rate of 0.10 ounces per acre, Envoke offers pre-emergent residual control of glyphosate-resistant horseweed and tough winter annuals including shepherd’s purse, henbit and annual bluegrass.

For control of emerged weeds, Envoke at 0.10 ounces per acre may be tank-mixed with Gramoxone Inteon, Touchdown HiTech, Touchdown Total, Roundup brands and other glyphosate products as well as synthetic auxin herbicides such as dicamba and 2,4-D. Always add 0.25 percent v/v NIS to Envoke applied alone or in tank-mixes for emerged weed control.

“We’ve looked at fall-applied products at various rates for two years,” said Steckel. “We have gotten very, very good residual control of horseweed with low rates of Envoke.”

Syngenta and university cooperator trials have confirmed that even in heavily infested fields, a fall application of Envoke provides effective knockdown and long-lasting residual activity, setting the stage for a clean start at planting and improved crop emergence.

Cotton may be planted three months following a fall/early winter application of Envoke. Consult the Envoke label and labels of all tank-mix partners for rotational restrictions and application requirements.

“We have been looking for a way to thin the horseweed populations in the fall so they are manageable in the spring. Although Valor provided sufficient control through the end of January, it was breaking by mid-March. Envoke was certainly superior in level and length of control,” said Dan Poston, Mississippi State University Extension weed scientist.