A noxious pigweed, the highly productive Palmer amaranth has been added to South Dakota’s list of prohibited noxious weed seeds. Seed for sale within South Dakota may not contain prohibited noxious weed seeds, including Palmer amaranth, in any amount.
Palmer amaranth was first spotted in South Dakota in 2014. Infestations are mostly in the central part of the state. One new infestation discovered last year in Potter County appears to have come mixed with millet seed.
Minnesota and North Dakota farmers have been finding the weed in their fields as well. Some came in with cattle feed and some with millet plantings.
Palmer seed joins the list of prohibited weed seeds in South Dakota, which includes Canada thistle, field bindweed, hoary cress, horse nettle, leafy spurge, perennial sowthistle, and Russian knapweed.
The state also added restrictions for weed seeds in seed mixes. Noxious weed seeds cannot exceed a cumulative total of 20 per pound of seed as of Sept. 2. Restricted noxious weed seeds are highly objectionable and difficult to control in specific crops, fields, lawns, and gardens. Restricted noxious weed seeds include annual bluegrass, dodder, field pennycress, giant foxtail, hedge bindweed, musk thistle, plumeless thistle, quackgrass, spotted knapweed, wild carrot, wild mustard, and wild oats.
Seed for sale from bluestems, gramas, Indiangrass, and prairie sandreed may not contain weed seed more than 3% by weight. Seed for sale other than these grasses may not contain weed seed more than one percent by weight.
South Dakota Department of Agriculture officials encourage those buying seed to carefully examine the labels of their seed purchases and ask to see the official seed analysis report if a percentage of weed seed is listed. Doing so will help deter the spread of weeds in South Dakota, they said in a news release.