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Communications > Sustainability Plus > Posts > Tennessee Valley Growers Face "Now or Never" Scenario with Resistant Pigweed

The lyrics of the Elvis Presley classic could be readily applied to the plight of Tennessee Valley row-crop producers battling the spread of Roundup-resistant pigweed: "It's now or never."

The reality couldn't be any more clear-cut or the stakes any higher: Producers must find some way to control the spread of the weeds this year or face dire consequences next year.

A lot is at stake, including an environmentally friendly cropping system that has been in place now for more than a generation and that, in addition to affording growers tremendous costs savings, has also conferred immense environmental advantages on the Tennessee Valley.

Until now, glyphosate, commonly known as Roundup, made this environmentally friendly, cost-effective cropping system possible. Glyphosate, used in tandem with row crops genetically altered to resist over-the-top applications of this herbicide, enabled farmers to reduce costly crop tillage and, in some cases, eliminate it entirely. The environment benefitted too: In addition to saving producers lots of money, reduced tillage also prevented topsoil erosion as well as chemical runoff into surface water.

The emergence of a pigweed genotype resistant to glyphosate applications changed all of this. As producers notice more and more of this resistant weed rising above their crop canopies, they're wondering if this cost-effective cropping system will be feasible in coming years.

One expert is still holding out hope, though he says much of this will depend on how well farmers manage to contain the spread of the weed this year — one reason why he believes 2010 may be remembered as a make-or-break year.

"In my opinion, if we can control these weeds before they reach the numbers they have in south Georgia, we can retain our conservation tillage practices, at least, for the most part," says Eric Schavey, an Alabama Cooperative Extension System agronomy agent who is working with growers in the Tennessee Valley.

Prevention is everything, he says.

Right now, only patches of resistant pigweed are turning up in Tennessee Valley fields — small enough to contain if farmers are willing to do whatever it takes, including hand pruning.

"Those who have only two or three plants — how hard is it to go out and prune these by hand?" Schavey asks.

In cases where the weeds have grown beyond a handful, he says herbicide treatments are warranted, even if this means killing some of the crop too.

"You will be better off killing this pigweed along with whatever yield you have in this infected area than doing nothing and allowing these weeds to carry over into next year," he says.

Why the need for such a ruthless approach? Because of these weed's awesome reproductive potential, Schavey says.

"We're talking about a single plant producing hundreds of thousands of seeds," he says. "So, if you have already got a thousand plants in the field, well, you do the math."

Doing nothing this year will almost guarantee a field teeming in resistant pigweed next year, he says.

While Schavey remains optimistic, he believes the future of conservation tillage in the Tennessee Valley will likely hinge on how effective growers are in preventing the weed's further spread.

One characteristic associated with pigweed that affords growers with a distinct advantage: its short-lived seeds.

Pigweed seed, while unusually prolific, is viable for only three years, Schavey says.

"If we can control the weed for the next three years, we can get a handle on this and retain most of the cropping systems we have in place now."

However, barring this effective control, Schavey says growers will be forced to return to much older cropping systems that not only will require increased tillage but also costlier, less environmentally friendly preemergent herbicides — not an appealing option to growers who are already struggling to contain costs.