The cost of hand-pulling weeds could run as high as $100 per acre in fields with a high concentration of the pigweed, although he personally has not had any that were that severe. Combining herbicide cocktails has also been successful, although the additional applications also increases costs.

That presents additional economic pressure in a year in which cotton farmers already are squeezed.

“There’s not any room — the way the cotton prices are, and the chemical costs and fuel costs — it’s going to be a struggle just to get your money back,” Robinson said.

In the future, Robinson, who uses conservation-tillage practices that use minimal tilling, said he may have to examine whether more harrowing, and the additional costs that will mean, is more economical than battling the resistant pigweed later in the farm season.

“I don’t know how we’re going to handle them,” he said. “I know we’re going to have to make some changes. I don’t know what we’re going to do. We’re going to have to do something to control this pigweed.”

In the meantime Robinson is making cleaning equipment a top priority to avoid transporting the resistant pigweed.

“A cotton picker is a major cause of picking them up,” he said. “Seeds get on the head of a cotton picker. You might leave some in every field. That’s probably my biggest fear is contaminating equipment and moving them myself.”

In terms of new technology to combat the Palmer amaranth, farmers will have to wait until 2013 or 2014, said University of Georgia extension agronomist Stanley Culpepper.

That technology will come in the form of seed with genetic resistance to a chemical that can be applied to cotton.

In the interim farmers will have to use other methods of control that can increase weed control cost by three times, Culpepper said.

“The only economical program at this point is to prevent it from getting a foothold on your farm,” he said. “If you as a grower can keep it out for two or three years, that is the best thing you can do.”

That means battling the pigweed early, as a quarter inch plant with the resistance can survive a solution of Roundup applied at 10 times the normal amount, he said.

“It’s devastating our cotton industry,” Culpepper said. “In simplistic terms it means a complete change in managing weeds in Roundup-ready cotton. The ease of the program, the economics of the program are all going to go away.

“When you develop resistance to it where you don’t even slow down the growth of pigweed, you’ve lost the most economical way to control this pest.”