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K-State Turf and Landscape Blog

Not Your Father’s Knotweed

(By Jared Hoyle, KSU Turfgrass Research and Extension)

For the past couple years I have posted on prostrate knotweed (Polygonum aviculare) control in turfgrass systems.  Guess what… it is that time of year again.  I have been seeing knotweed germinate all across campus and in areas where turf is thin.  Knotweed can grow in compacted soils where turf can’t survive. So after you get control of that knotweed make sure you aerify to relieve the compaction (Check out my recent post on aerification – http://blogs.k-state.edu/turf/new-aerating-your-lawn-ksre-publication/) and get some healthy turfgrass growing.

There are going to be some new products coming to the market soon that we have tested on prostrate knotweed that have shown excellent control.  So keep a lookout for new broadleaf herbicides (Hopefully they will be out either late this year or early next year).  When they hit the market you will hear all about it and next year when I post about knotweed control hopefully they will be released and I can add it to the list!

If you didn’t get your preemerge out in the fall for control and you have a history of knotweed it is time to go out and attack the knotweed and other broadleaf weeds you have lingering around.  These weeds are easier to control now when they are young compared to when they get mature.

Below is the Knotweed Control Turfgrass Selfie Series Video I did last year but here are the take home messages;

  • Early germinating summer annual
  • Likes compacted soils/flooded areas
  • 2,4-D = fair control
  • 2,4-D + triclopyr or dicamba = excellent control
  • metsulfuron can be used in warm-season turf
  • PRE applications must be done in the Fall

Always remember to READ THE LABEL for the correct rate, turfgrass tolerance, and specific instructions before application!!!

***Mention of trade names or commercial products in this article is solely for identification purposes and does not imply recommendation or endorsement, nor is criticism implied of similar products not mentioned by Kansas State University.***

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