Within a seven to 10-month lifespan, a single plant can churn out 500,000 to 1 million pinhead-size seeds. Just a few escapes equates to several million seeds jumping into the soil bank.
Walking fields in Coahoma County, Miss., for more than 40 years, consultant Bob Stonestreet is highly familiar with the Palmer threat. “We stay on pigweed early with herbicides, but anytime you deal with Mother Nature, nothing is foolproof. A lot of it boils down to money and time,” he says. When he finds Palmer escapes, Stonestreet ties colored tape on the ends of rows to mark the spot for removal by farm workers. He sees a variety of methods used to control Palmer. “Most farmers are forced to use some form of hand removal, but every operation is different,” he says. “Beyond choppers, I’ve seen designated labor riding the turn rows in a truck, actually intent on finding pigweed.”
Armed with traditional hoes, farmer Scott Flowers, Mattson, Miss., runs two eight-man weed chopper crews from 6 a.m. until noon. Paid by the hour, 16 employees working rows through mid-August exacts a big financial bite, but the alternative is risky. Flowers held back on chopping crews in 2015 and paid for it with yield-affecting weed infestations in some fields. In 2016, he’s spent the most money of his career on weed choppers—a necessary evil. “You can’t get all the pigweed with chemicals. Chopping crews are a tool I wish I didn’t have to use, but let pigweed go one year and then you can’t catch up the next year,” he says.
Palmer should be cut below the soil surface to prevent regrowth, says Jason Bond, Extension weed scientist, Mississippi State University. “Pulled pigweeds should be taken off-site and preferably burned, but if a producer at least gets pigweeds out of the field, that’s better than nothing,” Bond says.
In 2009, Kevin Bradley, University of Missouri Extension weed scientist, started documenting the spread of Palmer from the Bootheel to 32 counties across the state. He sometimes sees seeded Palmer piled on turn rows, an ineffective means of removal. “Sure, it temporarily keeps pigweed out of the rows, but seed remains and will wind up right back in the same fields,” he notes.
The logistics of controlling Palmer post-emergence are extremely difficult and ignoring an outbreak can be disastrous. “Without question, the pigweed footprint is expanding across the state,” Bradley adds. “This is not one we want to deal with, but we can’t go back and close the barn door.”