What is in this article?:
• The three keys to managing pigweed are: Start clean, overlap residual herbicides, and manage escapes.
• To manage pigweed the seed bank must be stable or decreasing every planting season to achieve sustainability.
FAILING TO MANAGE glyphosate resistant weeds for just one year can lead to a big problem
Not a cheap option
“On about 10,000 acres of cotton, we kept an overlap of residual herbicides and used different families of herbicides. It’s not cheap to overlap these herbicides, but it cleaned up most of our land.
“We still had a few fields with pigweed and we used hot-spot treatments to try and get to zero tolerance on pigweed. On the escapes we did have, we used hand labor to remove those weeds from our fields.
“We didn’t quite make it to zero tolerance, but it was a big improvement and it showed up in our cotton quality and yield. It takes a lot of work and it’s not cheap, but you can control pigweed. And, controlling them is a lot cheaper than losing the numbers game to pigweed,” Flowers says.
Wannamaker says he has made pigweed a top priority since he first began growing cotton. “My son told me, “Daddy I can’t believe you’d walk a half mile across a cotton field to pull up one weed.” “I knew when Roundup Ready cotton came to the farm there would be more cotton acres, because we could control pigweed, he adds.
The South Carolina grower says he applies glyphosate in February or March to burn down pigweed that survived the winter. He comes back right before planting with Gramoxone for a second burn-down.
“It’s real important to get the Gramoxone down close to planting, because we are susceptible to having rain at that time of the year and Gramoxone, rain and pigweed just don’t go well together, Wannamaker says.
He applies Reflex right behind the planter. Then, he comes back with a hooded application of Gramoxone and Valor — not on all his acreage.
“We have what I call families of pigweed that survive from one year to the next. So, in June I hire a crew to come in and clean up these areas. If we miss it with chemicals, we turn to hand labor — it’s costly, but it’s the only way we’ve been successful in managing pigweed,” the South Carolina grower adds.
“I think you have to have the attitude that I don’t want one pigweed in my cotton. We make it as hard as possible for a pigweed to grow to be an adult — it’s a numbers game we don’t want to play,” Wannamaker says.
Smith, who has preached the evils of Palmer pigweed across the Cotton Belt for the past few years, says taking a zero tolerance to these weeds is important. “I had one grower tell me, my grandfather farmed this land and my grandchildren will likely farm it, and I’m not going to let pigweed prevent that from happening.”
“That’s the kind of attitude a farmer had better have, if he is planning on managing pigweed in an environment in which more and more weeds are tolerant of the No. 1 herbicide used to kill them,” the Arkansas weed scientist says.
Smith asked the 200 or so cotton farmers to raise their hand, if they are growing less cotton than they were 10 years ago. Acknowledging that no one raised a hand, Smith says, “Like it or don’t, farmers are planting more acres, and they can’t go back to the size operation they had before we had glyphosate tolerant cotton plants,” Smith says.