2,4-D (Key Herbicide) Showing Signs Of Losing Effectiveness - Reuters [View all]

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(Reuters) - As U.S. farmers struggle to control the rise of "superweeds" choking key crop land, a leading herbicide known as 2,4-D that has shown good weed control for decades appears to be losing its effectiveness, a report from a science journal said on Wednesday.

Chemical makers have been racing to find an answer to resistance that has built up against the broadly used glyphosate-based Roundup herbicide, and they had hoped 2,4-D was at least a partial answer to the problem of how to stop weeds that can reach 6 foot tall or more and decimate crop production.

Dow Chemical unit Dow AgroSciences is seeking federal regulatory approval to roll out corn, soybeans and cotton that are genetically altered to tolerate treatments of glyphosate and a 2,4-D based herbicide by Dow called Enlist.

The aim is to wipe out weeds that have become resistant to glyphosate alone. Many critics have protested Dow's plans, citing fears of increasing weed resistance along with other environmental concerns. But Dow has said its new herbicide and 2,4-D cropping system is needed to fight back the weeds that have taken over millions of acres of key U.S. farmland.

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http://www.reuters.com/article/2012/08/15/us-usa-agriculture-weeds-idUSBRE87E13420120815