Palmer amaranth, which can grow 3 inches a day, can release nearly a half-million seeds per plant. And because the weed is glyphosate-resistant, many growers in Southern states, in addition to spraying, have had to hire workers to go into their fields to chop down the weeds with hoes and pull them by hand.
"We're trying to get people's awareness up about these weeds," Loux said. "If we've seen Palmer amaranth in one or two sites, then it's most likely that we have it in more areas. But the more we can make people aware of it, the more we can do to slow it down in Ohio and control it because we've got to shut it down before it goes to seed."
The potential financial impact for growers is a resistance problem with yield loss because the weed competition couldn't be controlled, Loux said. Growers could find themselves in a position of having to pay $15 to $30 an acre to control it, and in some cases even higher costs have been incurred, from $20 to $40 per acre.
"If you come across what you think may be Palmer amaranth or waterhemp but you're in doubt, get it identified and we can make recommendations as to how to manage it," he said. "That could include tearing up the fields and replanting if it's found early enough in the season.
"While paying a crew to remove plants in mid-season is a viable solution though it carries a relatively high cost, the result of not doing so could be a substantial loss of income in future years."
More information about Palmer amaranth and waterhemp can be found at the OSU weed management website, http://agcrops.osu.edu/specialists/weeds.