Crop & Pest Report

Accessibility


| Share

Waterhemp in Roadside Ditches (07/30/20)

In my travels across southeast North Dakota the past two weeks, I have observed an abundant amount of waterhemp in our roadside ditches.

In my travels across southeast North Dakota the past two weeks, I have observed an abundant amount of waterhemp in our roadside ditches. The grass in many of these ditches is thinned or completely missing in spots, and waterhemp is the most prevalent weed that is filling that bare ground. This likely goes back to severe flooding last summer and fall that resulted in standing water in the ditches for days to weeks. These flooding events also likely moved waterhemp seed from the fields themselves into the ditches. By now, much of the waterhemp in these ditches is flowering and setting seed. If left unmanaged, this will be another source of waterhemp seed production which can contribute to problems in future years in nearby and adjacent fields.

wdsci.1 2

At this point in time, many herbicides will not completely control this waterhemp. Mowing will control some plants, and reduce the amount of viable seed produced compared to letting these areas go. An application of 2,4-D or dicamba can also help control these weeds. Many crops are well into their reproductive stages, so potential of off-target movement of auxinic herbicides should be considered. These areas will also likely be infested with waterhemp in future years, and some longer-term management options should be considered. First, overseeding or reseeding the bare areas with a competitive grass can help suppress waterhemp in future years. Pairing an aggressive groundcover with an auxinic herbicide such as 2,4-D, dicamba, or aminopyralid (Milestone) can provide greater waterhemp control in these areas. The worst thing we can do is let these areas continue to go to seed in future years and further propagate the waterhemp infestations across the state.

 

Joe Ikley

Extension Weed Specialist

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

USDA logo

Creative Commons License
Feel free to use and share this content, but please do so under the conditions of our Creative Commons license and our Rules for Use. Thanks.