In a worst-case situation, escaped Palmer amaranth – aka Palmer pigweed – often requires direct human intervention. In other words, using muscle power to take weeds out of the field.
And if you really want to put a zero-tolerance control program in place, expect to add a degree of manual labor to your weed management program. Escapes are inevitable, especially when farmers are on the front end of Palmer infestations and they have missed key signals that resistance has crept into fields.
Allowing even a few plants to make it through can lead to wider pressure going forward. Palmer pigweeds that deposit seeds will set farmers up for years of headaches, extra costs and other penalties. These include lower yields due to competition, heftier chemical budgets, plus added wear and tear on harvest equipment when pigweeds gain any kind of size.
Granted, manual weeding might seem like a stupidly simple task. But Palmer pigweed brings a new set of complexities to the field, and it may force you to rethink how you go after escapes.
#1. Palmer’s Ability To Return From The Dead.
With the spread of resistant Palmer, U.S. farmers and crop advisors have witnessed a very unsettling trait. Like a cat with 9 lives – or perhaps a zombie with roots – a Palmer pigweed left for dead can quickly come back to life.
Laying your chopped pigweeds in row middles is only asking for trouble, says Tom Barber, Arkansas Extension Weed Specialist. With soil contact and moisture – from irrigation or rain – Palmer can actually root from the node. Think of it as the Lazarus effect, no seed required.
“It will make small plants from each node, in fact, and each of those can grow up into a seed head,” Barber adds.
#2. Chopping Demands Attention And The Right Hoe.
Whacking away at weeds with a hoe seems like a basic kind of chore. But with Palmer’s strong urge to survive and aggressive root system, you can’t do a halfway job and expect perfect results.
“If you’re hoeing pigweed, you have to cut it deeply below the soil line to be effective,” says Barber.
A durable field hoe is also an important part of chopping, Barber adds.
When Arkansas farmers first encountered these hardy pigweed escapes in the last decade “it was actually tough to find a good hoe that could last,” Barber recalls. “If you’re going to chop them out, you can’t just use your standard garden hoe. Use a hoe that you can sharpen and re-sharpen and then re-sharpen some more.”
Some of the best hoes for pigweed are made out of disk blades, he adds. Whether it’s a hoe made on the farm or a manufactured implement, both can use recycled tillage blades for the business end of the tool.
#3. Pulling – The Ultimate Remedy.
Jeff Gunsolus, University of Minnesota weed scientist, stresses to his farmers the need to pull Palmer, plus move it out of the field and destroy it altogether.
His advice is simple enough: “Weed it, bag it, drag it and burn it.”
He’ll quickly tell you that the “drag it” part shouldn’t be taken literally, but those two words emphasize the need to totally remove the weed from the field.
Gunsolus believes this is the best approach for his growers to prevent further spreading of seed. Minnesota’s first confirmed instances of Palmer turned up in 2016 in Yellow Medicine County, and Gunsolus would like to minimize further finds. Pulling up plants should remove enough of the root system to keep them from rebounding.
In his 40 years as a weed scientist, Gunsolus says that Palmer is the only weed species he believes should be eradicated. The weed’s overwhelming march in the lower Corn Belt and South prove to Gunsolus that Palmer can’t be taken lightly.
Chuck Farr, an Arkansas crop consultant, says that in many cases it’s actually easier to pull pigweeds than to chop them out, especially if the ground is moist following rain or irrigation.
“The crews pull them, put them in trash bags and carry them to the edge of the field where the farmer loads them on a trailer, hauls them off and burns them,” says Farr. “We like getting them out of the field – zero tolerance.”
If pigweeds are in the advanced reproductive stage and might drop viable seed when handled, carefully bagging plants is even more important, Farr and others say.
Guy Collins, cotton Extension associate professor at North Carolina State University, also advocates hand pulling.
“Completely remove the plant from the ground, shake the dirt off the roots and turn the plant completely upside down and slip it into a large garbage bag,” he says. “If the plant has seed on it, you definitely need to remove it from the field.”
Collins always takes into account Palmer’s “strong will to survive” and sees pulling as the best way to deny plants a second chance.
“Chopping is more effective than doing nothing,” says Collins, “but keep in mind that a chopped plant can survive. When you pile up a bunch of them outside of the field and set them on fire they’re not coming back later.”
Realistically, not every Palmer pigweed can be easily yanked out of the soil. If it’s had enough time to grow, the plant’s root system may be too robust for easy extraction. Pulling a big plant out of dry, hardened soil often won’t be possible, either. In those cases, nothing beats a sturdy field hoe or even a shovel.
#4. Know When To Stop Spraying.
When farmers first encounter Palmer escapes they often assume something went wrong with the application and they spray again. It doesn’t work, and pigweeds go unfazed by the treatment. Spraying yet again won’t help, either. In the meantime, more pigweed might have emerged.
It’s important to recognize that resistance, in fact, is in place and hoeing and/or pulling are the last option.
One control objective should be to prevent Palmer from emerging until the canopy closes, says North Carolina’s Collins. After closure, cotton farmers have a few post-emergence options that can eliminate Palmer – provided it’s smaller than 3 inches in height or less, he says.
“Then if we have escapes, those are the ones we need to hand weed,” he continues. “Taking them out when they’re small is important – not only because of their effect on the current crop, but for weed management the following year.”
#5. Be Prepared To Pay.
Even before Roundup Ready crops rolled onto the market, “cotton chopping” crews had already started fading from the Southern landscape. But by the time glyphosate resistance turned into a full-blown problem, that labor pool was mostly gone. And with bigger equipment and further reliance on herbicides, few farmers had enough labor to make a dent in the problem.
With Palmer pigweeds scattered across hundreds of acres, nobody could keep up, and farmers weren’t sure who to call to hire a crew.
Now, though, hand removal of escapes is standard operating procedure on many Southern farms. Those growers, in fact, keep numbers stored in their cell phones for preferred chopping crews or labor contractors.
Hand weeding or chopping have become a line item in some growers’ cropping budgets.
Of course, farmers find all kinds of ways to pull together a crew on a spot basis – putting family to work, hiring high school kids or turning it over to regular employees during slow times.
But for many growers enough escapes develop to require a labor crew – typically migrant workers – who can move through fields and quickly dispatch Palmer pigweeds.
One source for these crews tends to be area vegetable producers who contract with migrant crews at harvest. Those workers and/or their labor contractors try to squeeze in as many hours in the field as possible during the season.
Depending on local needs, similar opportunities may exist.
For example: Clarkedale, Arkansas, producer and ginner Allen Helms makes arrangements to bring in his seasonal cotton gin crew a few weeks early every year to pull weeds. The weeding gives them a chance to pull in extra income on the front end of their seasonal migration.
These are Mexican citizens working through federal permits. They often return to work for Helms year after year, so he has a good deal of confidence in their work ethic not readily available in the local labor market.
“They want to work as many hours as they can and as many days as they can over a 4- to 6-week period,” says Helms.
Overall, weeding costs vary. Arkansas consultant Chuck Farr estimates that his clients spend $5 to $7 an acre chopping pigweed in cotton and soybeans in most years.
But if things get out of hand, costs increase – often dramatically. When PPO resistance suddenly exploded where Roundup Ready cotton had been planted, farmers spent upwards of $100 an acre on hoeing and pulling in worst-case situations, Farr says.
Herbicide failures or delayed applications likewise can lead to mass escapes and the need to call in crews. If rain stalls farmers from making overlapping residual herbicide applications after emergence, escapes are almost a given in fields with a history of heavy Palmer pressure.
Chopping crews usually enter his part of the state as early as July, Farr specifies. “That’s when you start seeing some escapes. We use the term ‘big weed’ to indicate we’re about to get aggressive with pulling and chopping Palmer.”
In the last decade the idea of manual weeding stemmed from panic as Roundup applications began failing. Now, it’s just a matter of course, says Farr.
“We’ll say, ‘Let’s go in and ‘big weed’ everything.’”