Each year, some Georgia farmers have to deal with pigweed that continues to grow after spraying with glyphosate. This usually happens due to weather conditions or improper spraying.

Specialists with the University of Georgia last fall suspected some pigweed in central Georgia were glyphosate resistant. Many field and greenhouse trials and heritability studies now show that the pigweed population in central Georgia has true resistance, says Stanley Culpepper, Extension weed scientist.

Farmers need to watch their fields carefully and remove any pigweed not hurt after a spray with glyphosate, he says. This could help keep resistant plants from spreading.

It's too early to say what long-term effect this will have on cotton production in Georgia. But if farmers are no longer able to control this weed with glyphosate, things will have to change.

Farmers may once again have to plow fields to manage pigweed, Culpepper says. This will cost them time and money.