Herbicide resistant weeds have changed the way Georgia cotton farms manage their crop and the potential exists that similar situations may develop across the Cotton Belt if farmers fail to heed lessons Georgia growers have learned.

Stanley Culpepper, Georgia Extension weed specialist, described the Georgia experience with amaranth species during the recent Texas Plant Protection Association annual meeting in College Station.

“Amaranth species resistance is changing the way we grow cotton across the belt,” Culpepper said. “We’ve seen significant changes the last five years because of this ‘super weed.’”

He said resistance came on rapidly in Georgia. “In 2004, we had resistance on one farm,” he said. “In 2005, we identified resistance in 2 counties. In 2009, we have 13 counties with resistant weeds.”

He said the problem occurs across the Southeast and Mid-south. “Growers created resistance with selection process by using only glyphosate herbicide,” he said.