July 3, 2012

Windmill grass (Choris verticillata)   has been moving into Iowa in the last few years.  This summer I am seeing more of it than ever.  This is a spreading, warm-season weed with a light green color.  It gets its name from its distinctive seedhead that looks like a windmill.  The seedhead will detach from the plant when the seed is mature and it will roll like a tumbleweed and spread its seed to other turf areas.  It is also known as tumble windmill grass in some regions.

Roundup will kill it non-selectively, but it is a great seed producer and it will come back.  The new herbicide Tenacity (mesotrione) is labeled for it.  I have not tried this yet myself, but I hear that it works well if you are persistent.  If anyone has experience with this, let me know.

I took the pictures below this morning near Nevada, Iowa.  This is typical of where it occurs.  I generally see it along curb sides and in compacted area, although it can show up in more open turf areas.



Nick Christians Professor

Nick Christians, Ph.D. – University professor of turfgrass management, Iowa State University, Department of Horticulture, Ames, IA, and adjunct faculty, Department of Agronomy, Iowa State University, Ames, IA. Dr. Christians received his B.S. from the Colorado State University ...