Michigan farmers appear to have dodged a developing environmental disaster with the much-touted USDA Pollinator Habitat Initiative and Conservation Reserve Program.

The program, meant to provide habitat for pollinating insects, is spreading bad seed, including seeds of the potentially devastating agricultural weed Palmer amaranth.

That doesn’t mean, however, that Michigan is free of herbicide-resistant Palmer amaranth.

Researchers at the University of Illinois says weed scientists in at least four Midwestern states are finding Palmer amaranth, a wildly prolific seed producer that grows up to 7 feet tall and is herbicide-resistant, in the pollinator seed.

But Michigan is not one of those states, yet.

Erin Hill, weed diagnostician and cover crop specialist at Michigan State University’s Department of Plant, Soil and Microbial Sciences, tells Michigan Farmer that Palmer amaranth has not been found in the 6,034 acres of Michigan land enrolled in the USDA Pollinator Habitat Initiative and Conservation Reserve Program.

Hill, who worked with the Indiana researchers on the study, says Palmer amaranth has been in 10 southwestern Michigan counties, but none was linked to the pollinator program. “Not that we know of,” she says.

Identifying the problem
Illinois project leader, crop sciences professor Aaron Hager, says his team traced the weed seed to at least one source: pollinator habitat seed sold by a company in the Midwest.

A tag on the seed mix claims it is 100% weed-free, but this was not the case when the Illinois team germinated the seeds and grew the plants in a greenhouse.

Crop sciences professor Aaron Hager finds several species of Amaranthus, including Palmer amaranth, in seed destined for conservation program lands.

TROUBLE: Crop sciences professor Aaron Hager finds several species of Amaranthus, including Palmer amaranth, in seed destined for conservation program lands. (Photo by L. Brian Stauffer, U of I)

Hager says they found seeds of several species of the genus Amaranthus, including smooth pigweed, waterhemp and Palmer amaranth.

The provider of the bad seed is one of dozens of companies that sell seed mixes used in the USDA Pollinator Habitat Initiative and Conservation Reserve Program.

 “We're not going to name the company because we don't think this is the only one distributing weed seeds in their pollinator seed,” Hager says in a statement.

Yvonne Odom, executive director of the Farm Service Agency in Champaign County, Ill., says USDA and FSA, which helps administer the program, do not license the seed companies or inspect the seed mixes farmers use in the pollinator program.

They do review the seed tags, which are supposed to accurately represent the varieties and abundance of seeds in the mix and the presence or absence of weeds, she says.

Thus far, researchers have found Palmer amaranth growing in dozens of counties. At least 35 of 48 counties in Iowa with Palmer infestations, two in Illinois, two in Ohio and one in Indiana saw the problem first on conservation program lands.

The University of Minnesota also recently identified its first occurrence of Palmer amaranth in Minnesota, on land enrolled in the pollinator habitat program. “These are just the ones that have been detected,” Hager says.

Growers and Extension educators need proactive guidance on how to prevent the newly introduced Palmer amaranth from moving onto agricultural land, Hager says. “I don't know whether those enrolled in the pollinator habitat program are allowed the flexibility needed to control these populations,” he says.

“We don't have any issues at all with the concept behind the pollinator habitat program; it's a good program. But because of this program, we've now introduced Palmer amaranth to potentially thousands of acres of land, and we need to know what we are going to be allowed to do to try to stem the spread of it. And we need to do that quickly.”

Hager says once established, herbicide-resistant Palmer amaranth is almost impossible to stop. Some cotton farmers in the South have discovered that it can ruin once-productive farmland in only a few years.

“There are a lot of scary stories about Palmer amaranth coming from the Midsouth,” he says. “It's hard to describe this species as anything less than potentially devastating. It's put people out of business before.”

Michigan’s problem
Michigan’s battle with Palmer amaranth dates back to 2010, when a grower in southwest Michigan reported he was not able to control “pigweed” in his soybean field with Roundup. The weed was identified as Palmer amaranth.

Palmer is not native to Michigan or to other states in the northern U.S., but it is native to the desert Southwest and is one of 10 common pigweeds in the Great Plains and the Southeast U.S.

A Michigan State University report calls Palmer pigweed, as it is referred to in the South, the most competitive and aggressive of the pigweed species.

The characteristics that make growers fearful of this weed include extended emergence patterns (mid-May to late-August and early-September in Michigan); rapid growth rate; high water-use efficiency with drought tolerance; high seed production, averaging 400,000 seeds a plant; separate male and female plants leading to a high degree of genetic diversity; potential hybridization with other pigweeds; and rapid development of herbicide resistance.

Palmer amaranth has been identified in 10 Michigan sites, and many of these populations have been confirmed resistant to glyphosate and the ALS-inhibiting herbicides.

Palmer amaranth seed samples collected from a St. Joseph County Roundup Ready soybean field were confirmed resistant to glyphosate through greenhouse testing at Michigan State University. The Palmer amaranth populations had a twentyfold level of resistance to glyphosate compared with a susceptible Palmer amaranth population obtained from Tennessee.

The university says some of these plants survived a 32-times rate of glyphosate — equivalent to 5.5 gallons of Roundup PowerMax. It identified this population as also resistant to ALS-inhibiting herbicides.

Odom says participants in USDA conservation programs who suspect that they have weeds such as Palmer amaranth growing in their pollinator plots should call their local FSA administrator to report the problem and ask for guidance.

Restricted mowing and applications of herbicides, she says, will likely be recommended for infestations.