What is in this article?:
• The next family of herbicides to enter the fray against herbicide resistant weeds was the family of PPO-based products that includes such popular cotton herbicides as Valor and Reflex.
• Losing these herbicides to resistance problems would severely hamper efforts by Southeastern cotton farmers to manage any combination of weed problems that includes pigweed.
THIS RESEARCH field in North Carolina is a good example of what not to do in managing herbicide resistant Palmer pigweed.
Losing families of herbicides in the ongoing battle against Palmer pigweed is tantamount to sending modern-day warriors out to fight battles with a bow and arrow.
And, winning the war against herbicide-resistant weeds is critical to the continued profitability of cotton production in the Southeast.
No-till production systems, combined with nearly exclusive use of glyphosate for weed control in the mid-1990s, dramatically changed the way cotton was grown in the Southeast. The combination allowed growers to use less labor and resulted in a switch from small to large acreage operations, especially cotton, in the Southeast.
The change in cotton production systems didn’t come without costs, and unfortunately many growers in the area have been paying a high price to stay in the game when resistant Palmer amaranth pigweeds occur.
Acetolactate synthate, or ALS-inhibiting herbicides, like Envoke and Staple are frequently used to manage a number of commonly occurring weeds in cotton.
Early on in the battle against Palmer amaranth pigweed, growers basically lost this family of herbicides in some areas of the Southeast due to widespread resistance by a number of weed pests, most prominently Palmer pigweed.
The well-documented resistance by pigweed to glyphosate provided a double-whammy for cotton and soybean growers, leaving them with few options. Or, more correctly, with fewer options that didn’t require lots of money and/or time to use.
The next family of herbicides to enter the fray against herbicide resistant weeds was the family of PPO-based products that includes such popular cotton herbicides as Valor and Reflex. Losing these herbicides to resistance problems would severely hamper efforts by Southeastern cotton farmers to manage any combination of weed problems that includes pigweed.
In the Southeast, so far so good with PPO herbicide use in cotton weed management.
Growers have been quick to recognize the potential future challenges of growing cotton and soybeans without this family of herbicides and most have limited the use of PPOs, especially in areas prone to glyphosate resistant pigweed.
However, a few hundred miles away, the news isn’t so promising. Waterhemp is a close cousin to Palmer amaranth and nearly a decade ago researchers documented resistance to multiple herbicides, the latest being PPO inhibitors, in soybeans in Illinois.