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Barnyardgrass in Agricultural Fields (08/06/20)

Is it me or is there more barnyardgrass in wheat and soybean fields in 2020 than other years? Of course, you have observed barnyardgrass on the side of roads, in ditches, wetlands, and even in lawns.

Is it me or is there more barnyardgrass in wheat and soybean fields in 2020 than other years? Of course, you have observed barnyardgrass on the side of roads, in ditches, wetlands, and even in lawns. However, I believe it is less common in agricultural fields in North Dakota and Minnesota. Perhaps we can credit its prevalence to weather conditions, especially moist conditions carrying over from fall 2019.

Barnyardgrass is a summer annual grass that begins to germinate in May or at the same time as foxtail species. Barnyardgrass produces a prolific number of seed, capable of producing more than 750,000 seeds. Thus, it is safe to assume we will have large barnyardgrass seedbanks in our soil for years to come. Barnyardgrass is an annual grass easy to identify. It lacks a ligule and auricle and has flattened stems. These three characteristics make it easy to identify when young and before flowering. Roots are fibrous and shallow. Tillers often form adventitious roots or roots formed from any non-root tissue and where they touch the soil.

Barnyardgrass flowers in July to September. The seed head is a coarsely branched green to purplish panicle. Spikelets are single seeded, barbed along the nerves, and can have a long terminal awn. Barnyardgrass plants are killed by the first hard frost, but the large thick stems and fan shape of the tillers may remain in the landscape well into winter.

A brief review of the 2020 North Dakota Weed Control Guide reveals many herbicide options for controlling barnyardgrass. Soil applied, herbicides from site of action (SOA) 3, 15 and 27 and postemergence herbicides from SOA 1, 2, 9, and 10 control barnyardgrass. I was pleasantly surprised to read that Liberty provides excellent barnyardgrass control as barnyardgrass is not a weed I would consider a real strong suit for the LibertyLink system.

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Tom Peters

Extension Sugarbeet Agronomist

NDSU & U of MN

 

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