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Waterhemp Identified Along the Red River, East of Grafton, ND (08/13/15)

It just keeps moving north! I walked along the Red River and a field adjacent to the Red River near state road 17, east of Grafton, ND and positively identified waterhemp last week.

Waterhemp Identified Along the Red River, East of Grafton, ND

It just keeps moving north! I walked along the Red River and a field adjacent to the Red River near state road 17, east of Grafton, ND and positively identified waterhemp last week. Our idea is waterhemp probably moved north in river water and found agricultural fields during spring flooding. According to Shawn Kasprick, Agronomist with Simplot, the river last flooded in this area in 2013, which may account for plants found in a field adjacent to the river.

What does this mean for Farmers? It means farmers must continue to implement the weeds management strategy, beginning with vigilant scouting and positive identification of weeds. Waterhemp is difficult to identify in the vegetative stage but is easy to identify once it gets larger and begins to flower. Begin by examining the stem and leaves. Redroot pigweed, smooth pigweed and powell amaranth have very fine hairs on stems and leaves throughout the plant. Waterhemp stem and leaves are smooth and contain no hairs. The flowering structure will also help to differentiate between waterhemp, redroot pigweed, powell amaranth and smooth pigweed. The flowering structure is branched and very compact and thick with redroot pigweed and powell amaranth. However, the length of redroot pigweed branches are much shorter, only 2 to 3 inches in length as compared to 4 to 8 inches with powell pigweed. Waterhemp and smooth pigweed have a highly branched flowering structure. Flowers are much more open with waterhemp and are located near the top of the plant and at the tips of branches.

As always, ask for help from your extension specialist, the county agent or your Ag retailer or consultant if you need help with weed identification. A wonderful on-line pigweed pictorial guide is available for download at the following link:  https://www.bookstore.ksre.ksu.edu/pubs/S80.pdf.

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Tom Peters

 Extension Sugarbeet Agronomist

NDSU & U of MN

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