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Waterhemp has Emerged in the Southern Red River Valley (05/19/16)

I received two images yesterday, one from near Sabin, MN and a second near Walcott, ND, confirming waterhemp has emerged in eastern North Dakota and Minnesota.

Waterhemp has Emerged in the Southern Red River Valley

I received two images yesterday, one from wdsci.waterhempnear Sabin, MN and a second near Walcott, ND, confirming waterhemp has emerged in eastern North Dakota and Minnesota. Waterhemp is in the pigweed family but typically germinates later than redroot pigweed. Waterhemp is very similar to redroot pigweed, especially when it is young. Waterhemp cotyledons tend to be wider than and not as long as redroot pigweed (rounded). First true leaves are lanceolate shaped.

I have been working on a Growing Degree Day (GDD) model to track waterhemp germination and emergence. GDDs have been used to classify weeds to simplify scouting (Iowa State University IPM-64). By tracking GDDs, it may be possible to estimate waterhemp germination and emergence in order to time application of soil-applied herbicides applied early postemergence herbicides (lay-by) in sugarbeet.

The model did not correctly estimate waterhemp germination and emergence indicating more development work will be needed. One positive, there is much greater knowledge and awareness of waterhemp in corn, soybean and sugarbeet fields than a few years ago which is providing a stronger ‘training’ data set for adjusting the model for future use in future years.

 

Tom Peters

Extension Sugarbeet Agronomist

NDSU & U of MN

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