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Scout for palmer amaranth this fall
September 27, 2019

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Since palmer amaranth, the number one weed problem in the U.S., was first discovered in McIntosh County in 2018, seven more counties have identified this aggressive weed. Recently Morton County became the 8th N.D. county to identify this invasive weed. Currently, these counties have destroyed all visible plants and will be vigilantly monitoring these sites.

Palmer amaranth seeds can spread in a number of ways, including farm equipment, wildlife, wind and water. Seeds also have been found in native seed mixes used for pollinator or wildlife habitats and in hay.

Recently, county Extension offices received the following important information from NDSU Weed Scientist, Brian Jenks: "In the last 4 weeks, we have walked multiple millet fields and found Palmer amaranth. We encourage all farmers to walk millet fields and not just look from the road. Most plants cannot be seen from the road. In the picture below, can you see the two Palmer plants? One is obvious, but the other is not. The second plant is about a foot to the right of the taller plant. The long seedhead is just visible above the millet canopy.

The good news is that if caught early enough, these plants can be removed from the field before viable seed is produced and fall off the plant. Since millet generally is planted in June or July, viable seed may not be developed yet."

Jenks also says adopting a zero-tolerance policy is the only way this weed will be controlled.

The first step in managing Palmer amaranth is to look for it and identify it. Now is a good time to scout because Palmer amaranth is developing its distinctive long, snaky seed heads which can grow up to 2 feet long.

Identifying Palmer amaranth can be difficult because it resembles redroot pigweed, smooth pigweed and waterhemp. Here are some ways to distinguish Palmer amaranth from similar-looking weeds:

- Seedlings have egg-shaped leaves and may have a hairlike protrusion on the leaf tip.

- The leaves and stem have few or no hairs.

- The petiole (leaf stem) will be as long as or longer than the leaf blade.

Visit NDSU Extension's Palmer amaranth website at www.ag.ndsu.edu/palmeramaranth to learn more about the weed and how to identify it.

People who see a plant they suspect is palmer amaranth should contact their local NDSU Extension agent or an Extension specialist as soon as possible. DO NOT transport the suspect plant as this risks spreading seeds.

Schmidt is the NDSU Extension agent for Pierce County.

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