Delayed Weed Control Options in Cotton

Rainfall throughout the state has delayed weed control applications resulting in weeds that have become larger than desired and more difficult to control.  Several calls have come in regarding sequential application options for management of glyphosate-resistant pigweeds and other species.  Weed management options are listed below depending on the technology containing in the crop in your field.

In Bollgard II/Roundup Ready Flex Cotton:

Glyphosate (32 fl oz/ac of a fully loaded product or equivalent) + Staple LX – 2.6 fl oz/ac.  Staple LX and Dual Magnum cannot be tankmixed.  Limited pigweed activity.

Glyphosate (32 fl oz/ac of a fully loaded product or equivalent) + Envoke – 0.15 oz/ac.  You may add a metolachlor (Dual Magnum, etc.) or Warrant to this application if you need residual weed control.  Cotton must have 5 leaves prior to applying Envoke.  Limited pigweed activity.

If you do not add a residual herbicide in the first application, make a second glyphosate application a week to 10 days after the first with a residual herbicide in the tank.  If a residual herbicide is added in the first application, a second application may still be needed for optimum weed control and should be made 10-14 days after the first application.

In Widestrike Roundup Ready Flex Cotton:

Glyphosate (32 fl oz/ac of a fully loaded product or equivalent) + Staple LX – 2.6 fl oz/ac.  Staple LX and Dual Magnum cannot be tankmixed.  Limited pigweed activity.

Glyphosate (32 fl oz/ac of a fully loaded product or equivalent) + Envoke – 0.15 oz/ac.  You may add a metolachlor (Dual Magnum, etc.) or Warrant to this application if you need residual weed control.  Cotton must have 5 leaves prior to applying Envoke.  Limited pigweed activity.

Liberty – 29 fl oz/ac – follow the initial application with a second application in ten days.  Keep in mind injury may occur from these applications.  If a third application is needed, yield loss will likely occur; however, yield losses from lack of weed control versus from potential herbicide injury should be considered on a field by field basis.  In addition, keep label restrictions on total product usage per season in mind.  If a residual herbicide is needed, do not tank mix with Liberty on Widestrike cotton as injury will likely occur.

In Glytol/Liberty Link Cotton:

Glyphosate (32 fl oz/ac of a fully loaded product or equivalent) or Liberty + Staple LX – 2.6 fl oz/ac.  Staple LX and Dual Magnum cannot be tankmixed.  Limited pigweed activity.

Glyphosate (32 fl oz/ac of a fully loaded product or equivalent) + Envoke – 0.15 oz/ac.  You may add a metolachlor (Dual Magnum, etc.) or Warrant to this application if you need residual weed control.  Cotton must have 5 leaves prior to applying Envoke.  By label, Liberty and Envoke cannot be tankmixed.  Limited pigweed activity.

Liberty – 29 fl oz/ac.  Liberty may be applied up to three times per season at 29 fl oz per application.  Up to 43 fl oz/ac may be applied in a single application; however, the second application is restricted to 29 fl oz/ac and a third application is not allowed by label.  Dual Magnum (or equivalent) or Warrant may be added to Liberty for residual weed control.