Another option if growers prefer to apply Reflex behind the planter is to include a tank-mix partner, such as Diuron or Cotoran. This gets two modes of action on the pigweed and drives the chances for resistance way down. “ Cahoon says.

The take home message, Cahoon adds, is the value of a residual herbicide as a part of a preplant burndown application in no-till cotton. 

Residual herbicides used preplant protect growers from a failure of pre-emergence herbicides applied at planting, he says.

“Our two primary options preplant here in North Carolina include Valor SX and Diuron. However, when we saw dry weather at planting, Valor SX outperformed Diuron, so it looks like we should keep Valor SX preplant.” Cahoon says.

The North Carolina researchers explored the same treatments using both a Liberty Link and a Roundup system. Cahoon says they saw similar results when substituting Diuron for one of the PPO-inhibitors, regardless of whether glyphosate or glufosinate herbicides were used as a primary weed management tool.

With cotton acreage down this year and expected to drop again in 2013, growers are likely to put more cotton on their most highly productive land. This will put a higher premium on early-season weed management because of its well documented impact on final cotton yields.

York stresses the importance of using multiple herbicide families to improve efficacy of weed control and at the same time slow down the ever-worsening problem with herbicide-resistant weeds, most prominently pigweed.

Several new herbicide products, or more precisely combinations of herbicides and new technology, are likely to be available for cotton growers in the near future.

However, there are no new families of herbicides on the horizon. So it is critical for long-term cotton production in the Southeast to conserve the longevity of herbicide tools we currently have by using them wisely.

rroberson@farmpress.com