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Serving: West
Palmer amaranth closeup SDSU
WEED ID: If you see unusual weeds on your farm, such as this Palmer amaranth, be curious and get it identified. It could be a species new to your area.

Curiosity pays off when it comes to weeds in your field

Don’t ignore that pigweed if it doesn’t look right; ask for help identifying it.

Every year, we see interesting things in the field that re-establish what is “normal.”

For example, prior to 2017, narrowleaf hawksbeard occurred in insignificant areas of fields and along roadsides in western North Dakota, but widespread infestations occurred in Canada and Montana. In 2017, heavy populations and widespread distribution of narrowleaf hawksbeard occurred in North Dakota. You probably have seen it if you live in Williams County. It’s the plant that overwinters in the rosette stage and forms an elongated stem with yellow flowers in the spring.

Recently, a homeowner found a plant specimen identified as narrowleaf hawksbeard in Grand Forks County, N.D. How did a weed of the West find its way to the East?

Another example is waterhemp. Waterhemp belongs to the botanical Amaranth family, which also includes other pigweed species found in North Dakota and Minnesota, including redroot pigweed, Powell pigweed and smooth pigweed.

Waterhemp plants are either male or female. Thus, male plants produce only pollen, while female plants produce only seed. This type of biology leads to cross-pollination, or the fertilization of female plants with pollen from one or more male plants. Cross-pollination can greatly increase the genetic diversity of a population, and with genetic diversity comes a wide range of morphological and biological characteristics.

Seeds produced by female waterhemp plants are small and usually germinate from very shallow depths in the soil (1/2 inch or less). The number of seeds produced by female waterhemp plants can vary depending on many factors. Waterhemp has been a “game changer” due to its wide period of germination and emergence and due to its herbicide resistance.

Most agriculturalists associate waterhemp with the eastern portion of the state of North Dakota or areas east of U.S. Highway 281. However, in 2018, waterhemp was identified in central and western areas of North Dakota. Last year, a homeowner from Beach, N.D., sent in a sample that was identified as waterhemp.

Once again, how does a pigweed that is common in the east find its ways to Beach, one of the most westerly communities in North Dakota?

Weeds spread by natural methods including wind, water and animals. They are also spread by humans on vehicles, attached to equipment such as combines or tillage, and in contaminated seed or feed. Following the 2017 drought, large quantities of hay baled in Wisconsin, Kansas and Nebraska were shipped to North Dakota. While the intent was positive, it is possible that donated and purchased hay contained weeds and weed seed.

Be curious about the weeds you observe in fields, pastures and gardens. Ask for assistance in identifying weeds if your pigweed doesn’t look like other pigweeds in your community. Call your county agent and ask your crop consultant or ag-retailer. Call a state Extension specialist. But, above all, be curious.

Peters is a North Dakota State University and University of Minnesota Extension sugarbeet agronomist

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