Progress Against Pigweed


A decade and nearly $1 billion have been spent on the management of glyphosate-resistant Palmer amaranth by Geo-rgia cotton producers. Who could have known in 2004 when we couldn’t kill a pigweed with Roundup in Macon County, Ga., that our entire agricultural industry was beginning the process of changing forever. Many have called Palmer amaranth a superweed. Some have called it a cancer. I believe it’s simply a biological stud.

Regardless of what the weed is called, the decade-long war has required more herbicides, more tillage, more hand weeding, more cussing, and greater expenses than ever imagined.

Many often ask if there is a silver lining from our struggles; the answer is clearly yes. The transformation of the, let’s say, occasional untimely producer who relied a little too much on Roundup to a very knowledgeable, aggressive and timely producer has been amazing. Not only has this transformation led to much better farmers, it has led to much greater, and often exceptional, control of Palmer amaranth. However, an economically sustainable solution continues to elude us.

Several critical steps that have proven successful across the state often include the following:

• Producers are diversified and do not rely exclusively on a herbicide program. Hand weeding (92 percent of growers), tillage and/or cover crops are implemented in conjunction with the herbicide program across the board. Producers who rely exclusively on a herbicide program to control Palmer amaranth may not survive in Georgia.

• Herbicide programs are extremely diverse with the average cotton program including five to seven herbicide modes of action on every acre.

• Herbicides are applied at appropriate rates and are not applied at sub-lethal, non-recommended, rates.

• When economical, rotation to crops such as corn or sorghum allows a crop more competitive with the weed to be grown while using effective alternative chemistries not used in cotton.

• Producers never plant into fields with emerged Palmer amaranth; if they do, they usually end up starting over after being forced to conduct heavy tillage.

• Equipment sanitation is employed whenever feasible. Some producers in Georgia are doing so well that it is critical to not re-infest fields that have been nightmares in the past.

• Seedbank management has been one of our greatest successes and perhaps the greatest success. More than 90 percent of Georgia cotton farmers have hand-weeded their crops for at least the last four years.

Several other factors have influenced our success. First, at least in Georgia, the consistent and uniform message from Extension, consultants, industry, dealers and distributors has been essential in the overall success. Our ability to disseminate the same message to our producers over the last decade was remarkable.

Also, I must mention the importance of the Roundup Rewards program for cotton developed by Monsanto many years ago. The Rewards program has primarily supported products recommended by Extension. I can assure you that management programs developed by university Extension are not based on a rewards program; they are based on sound, repeatable science. Thus, for a Rewards program to support science while helping producers implement effective (usually residual) herbicides into a system is admirable.

Our challenges in Georgia are still great. Some producers continue to struggle in controlling Palmer amaranth while all producers continue to struggle controlling the weed economically. Regardless, our producers should be proud of their successes as we cooperatively search for more economically sustainable solutions.

– Stanley Culpepper, Tifton, Ga.


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