Production Blog
Pam Smith DTN\Progressive Farmer Crops Technology Editor

Thursday 08/16/12

Pigweed Gets Loose in Illinois

COLLINSVILLE, Ill. (DTN) -- Most companies bring farmers to field days to show off a crop. On August 15, Bayer CropScience brought farmers to the field to gawk at weeds.

There are actually soybeans in this field located near Collinsville, Ill. It's hard to spot the oilseed amid the forest of Palmer amaranth. (DTN photo by Pam Smith)

Not just any weed either -- a population of glyphosate-resistant Palmer amaranth near Collinsville, Ill., has served as a test lab this summer for herbicide trials. While there was some waterhemp present, the pigweed specimens towering above the crop gathered most of the attention. Pigweed had completely overrun the soybeans in most of the plots.

The Bayer initiative is called "Respect the Rotation" -- an effort to get growers to take steps to fight the proliferation of glyphosate-resistant weeds.

Andy Hurst, Bayer CropScience product manager for the LibertyLink trait, said the company wants to give producers an intimate look at what weed resistance looks like locally and what it could mean to their farm. Southern growers have been in a full tilt war against Palmer amaranth for several years, but Midwest growers have been slower to accept the threat.

"It scared me," Delmar Volentine, who farms near Sorento, Ill., told DTN.

Southern Illinois University weed scientist Bryan Young has been conducting much of the work at the plot this summer. He said the farmer who owns the property noticed problems two years ago and the pigweed spread dramatically in a short period of time. He estimated Illinois currently has about 2,000 acres of Palmer amaranth. It has also been found in a few spots in Indiana and Michigan.

Drought affected the Collinsville area this year and Young said he irrigated the plot five times throughout the season. He figured some of the seedling Palmer pigweed might not have survived as well had the land not been irrigated. However, Palmer amaranth got an early foothold this year and it is a desert plant with a long taproot that allows it to thrive on little water. Irrigation water was also necessary to get proper activation of the residual herbicides being tested.

When Young picked up a soil sample from the field and showed growers the pigweed seeds within, the crowd muttered about leaving their shoes behind. "I washed all equipment and my shoes multiple times every time I work at this location," Young said.

Growers are urged to scout their fields this fall. Palmer amaranth may have only started getting a foothold in the Midwest, but cousin waterhemp is a bonafide resident. The key to planning a program for next season is to know what you faced this year.

Indicators of potential weed resistance include:

-- A patch of weeds occur in the same area year after year and you've noticed they are spreading.

-- Dead weeds appear next to surviving weeds after the same herbicide application.

-- Many weed species are managed, but one particular weed species is no longer controlled.

Contact your local state Extension service or state weed specialist if you suspect herbicide resistant weeds.

Pamela Smith can be reached at

Posted at 1:39PM CDT 08/16/12 by Pam Smith
Comments (3)
Glyphosate resistance to non-native Palmer Amaranth has been a growing issue for nearly a decade or more. Native to the desert SW, it's presence in the N Central plains is something that should be investigated on it's own merits. However, 2,4-D, in use in Nebraska for nearly a decade is also showing signs of resistance, as this article from the Chicago Tribune discusses: Stacking these additional traits seems to be fostering resistance even faster than it developed for Glyphosate, but again, Palmer Amaranth, a plainly desert plant, "suddenly appearing" in Illinois, is odd to say the least. It's a veritable disaster in your field, particularly the resistant varieties, which are denser, tougher and more voracious a glutton for soil nutrients than Pigweed 1.0 was.
Posted by Ric Ohge at 10:18AM CDT 08/17/12
Are there possible uses for this plant such as biomass production or feed value?
Posted by Darle Baker at 8:47PM CDT 09/07/12
Darle--An internet search turns up that researchers at New Mexico State University have looked and perhaps are still looking at the amaranthus species as a possible biomass crop. I'm guessing Palmer would be problematic in most areas though because it has both male and female plants and possible spread by pollen would make growing it near any commercial agricultural areas very unlikely/unpopular...just me thinking aloud here. As for feed, I believe nitrates can build up in it quickly when it is in highly fertile environments. It appears it is a crop that can be/has been consumed, but seems to have such a noxious weed status that encouraging it as crop seems unlikely.
Posted by Pamela Smith at 8:49AM CDT 09/09/12
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