Navigating a post-glyphosate landscape, part II

The lives of farmers have never been easy. To an increasing degree, they are working to balance the demands of farm profitability against higher expectations among public watchdogs and policy makers for enhanced standards of environmental stewardship.

The ensuing battle with glyphosate-resistant pigweed only underscores this fact. During the past couple of decades, glyphosate has conferred many advantages on farmers. The potent product, used in tandem with genetically modified, glyphosate-resistant row crops, such as cotton and soybeans, has enabled producers not only to deal with weeds more efficiently and cheaply but also to adopt environmentally friendly tillage practices.

Weed resistance has changed all this.

As the New York Times reported earlier this month, a growing number of producers, especially in the South, are being forced to spray fields with older, comparatively less effective herbicides. Some have even been forced to resort to tillage and hand weeding.

"The economics of crop control have played a major role in the methods to control weeds," says Michael Patterson, an Alabama Cooperative Extension System weed scientist and Auburn University professor of agronomy and soils.

"However, glyphosate-resistant weeds have changed this equation and caused farmers to add more inputs into the system."

The renewed challenges have led some producers to wonder if it's possible to turn a profit in the absence of this standby product.

One Georgia farmer quoted in the article even likened weed resistance to a notorious 20th century cotton pest.

"If we don't whip this thing, it's going to be like what the boll weevil did to cotton," said Louis Perry Jr., chairman of the Georgia Cotton Commission and a Moultrie farmer.

That raises a pertinent question: Is weed control achievable in what is essentially a post-glyphosate era?

Some experts still believe it is.

"The short answer is yes," says Stephen Powles, professor of plant biology at the University of Western Australia, who is also a grain grower and glyphosate user.

Even so, he says this should be grounded in the realization that glyphosate is a "precious resource for current and future harvests."

For some producers already dealing with severe weed resistance, it's too late. But for many others, glyphosate remains a viable option, at least for producers willing to make more judicious use of the chemical.

"This will call for diversifying crops and giving glyphosate a rest by using other herbicides and non-chemical weed control tools that make sense. Diversity offers the best chance of saving glyphosate."

Blake Hurst, a northwestern Missouri producer, already has adopted such a strategy. In an interview in the New York Times, Hurst says he hasn't noticed a serious weed-resistant problem on his farm because he's using Roundup only every other year, while also using crop protection chemicals with various modes of action to reduce the risk of weed resistance.

Still, fully anticipating an increase in the levels of weed resistance in the future, he plans to reduce Roundup applications in the future to maintain the chemical's effectiveness.

Meanwhile, Scott M. Swinton, a professor of agricultural, food and resource economics at Michigan State University, advises farmers to borrow a page out of Sun Tzu's "The Art of War," the New York Times reports.

Swinton says a big part of a weed control strategy should involve understanding crop weeds and their vulnerabilities. Much as the wise warrior inflicts surprise on his enemies, producers should impose the same element of surprise on their cropland weeds.

Even so, study requires time, and it behooves farmers to take the time to study and consider their weed challenges. Strategies may involve a combination of crop rotation tillage and rotation, he says.

For his part, Patterson says rotation will be an integral part of the post-glyphosate landscape.

"Crop rotation — with the concurrent rotations of herbicides rotated with each crop — offers an opportunity to control glyphosate-resistant weeds with herbicides that kill based on different modes of action than glyphosate," Patterson says.

Yet again, economics must be factored in too.

"If this rotation crop doesn't fetch a high enough price, it isn't going to be a viable option," Patterson says.

TAGS: Management
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