BY DAVID SMITH Journal & Courier
LAFAYETTE, Ind. - A fast-spreading, herbicide-resistant weed with a villainous-sounding name is spreading noxious roots in 17 Indiana counties and may have a toehold in Tippecanoe, a Purdue University weed scientist says.
Palmer amaranth has been confirmed in 17 Indiana counties - up from seven last fall - and is no longer confined to the northwestern part of the state, Bill Johnson, Purdue professor of weed science, told the Journal & Courier (http://on.jconline.com/18Uwhim). It's been spotted in several counties next to or near Tippecanoe County.
Palmer amaranth is no ordinary weed. It packs a trio of characteristics that pose potentially costly challenges to producers, particularly soybean farmers, wherever it is found.
"One or two plants in an 80-acre cornfield can cause a train wreck the following year," Johnson said.
The plant can grow to abundant proportions, up to 7 feet high, rivaling giant ragweed in its ability to compete for sunlight, water and nutrients and reduce crop yields.
As if that weren't enough, a single plant can produce up to a million seeds.
"We really don't have another weed that can grow this rapidly and produce this much seed," Johnson said.
To top it off, Palmer amaranth is resistant to the two most common soybean herbicides, including Roundup, currently in use.
Controlling the weed requires an expensive cocktail of three or four herbicides at a cost of $50 to $60 an acre, compared to $15 to $20 an acre for less resistant weeds, Johnson said.
Clark Howey, who farms 700 acres of corn and beans just north of Odell in southwestern Tippecanoe County, said $50 to $60 to protect an acre of beans is a "very significant cost."
"That would be about the same price of beans to plant," he said.
The weed is not yet resistant to common corn herbicides.
Johnson encourages farmers to be vigilant and to attack the weed immediately with herbicides or by plucking it by hand - "Anything you can do to prevent it from going to seed."
Gary Kerkhoff, another Tippecanoe County farmer, said he hasn't yet encountered the weed, but he wouldn't necessarily recognize it if he did because it's unfamiliar and can be mistaken for common pigweed.
"That's our biggest problem, being able to identify it," Kerkhoff said.
Tippecanoe is not on the official list of counties where Palmer amaranth has been confirmed - yet.
Johnson has a hunch, however, based on indirect evidence.
"We're pretty sure there's some in the southern part of the county," he said