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Watch what you plant: Some native seed mixes contaminated with invasive weed

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Palmer amaranth
Palmer amaranth can shoot up as high as 7 feet, and just one plant can produce 500,000 to 1 million tiny seeds.
Courtesy of Bruce Potter | University of Minnesota Extension File

The Minnesota Department of Agriculture wants landowners to pay more attention to what seeds they plant this spring.

Native seed mixes contaminated with the invasive Palmer amaranth are a big concern for the agency.

"The reason that we're so focused on Palmer amaranth is because of its potential to impact corn and soybean production," said Denise Thiede, a program supervisor in the plant protection division.

The invasive plant first sprouted in Minnesota in 2016 in a field planted with a native seed mix. It's now found in four counties, where efforts have been undertaken to eradicate the plant before it can get established.

The plant spreads aggressively and is often herbicide resistant, so it can take over fields and reduce corn and soybean yields.

Seed mixes that contain native plants for use in conservation or pollinator habitat often come from a variety of sources and the Department of Agriculture has yet to trace the source of Palmer amaranth in the contaminated seed mixes.

"What I have seen in these investigations is that land owners are really unaware of the labeling law, and in some cases they have allowed unlabeled seed to be planted on their property," said Thiede.

Landowners should always ask a seed vendor for label information before buying seed. Likewise, Thiede said, landowners should make sure any seeding contractors use properly labeled seeds and never buy seed without a label.

"Landowners are the first line of defense, and they have information at their fingertips to help prevent this contamination."