Palmer amaranth has been confirmed in four more North Dakota counties.
First found in a row-crop field in McIntosh County this summer, it has been identified in Benson, Dickey, Foster and Richland counties.
Tom Peters, NDSU Extension sugar beet agronomist, said the likely sources were seeds carried by migratory birds, a used combine, an alternative feed source purchased out of state, custom combining and grain cleaned out of railroad cars.
Contaminated seed, wildlife, water, wind, potting soil, hay from other states and native seed mixes used for pollinator or wildlife habitats are among other ways Palmer amaranth seeds can spread.
Once someone contacts Extension about suspected Palmer amaranth, the field will be investigated to determine what the plant is. If necessary, samples will be sent away for DNA testing.
Additional information can be found at www.ag.ndsu.edu/palmeramaranth.