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Windmill Grass Rears Its Ugly Head

June 17, 2015

Here are a couple of pictures of Windmill grass (Choris verticillata) from Larry Ginger of American Lawn Care in Des Moines, Ia.  This warm-season grass is fairly new to Iowa, but I get more questions on it every year.  As it matures, it will form a large, open seedhead that looks a little like a windmill.  It spreads by stolons and by seed and increases every year in this area, particularly along city streets and on south facing slopes.  The seedhead will detach from the plant at maturity and roll over the turf like a tumble weed to spread its seed.  This is the main reason that it has spread so quickly. 
 

 

Roundup will kill it, but that will also kill the other lawn grasses.  Tenacity (mesotrione) is also labeled for it, but you will need to be persistent to completely remove it.

Search this blog for early articles on this species.

Here is a closeup of the seed head as it will appear in late summer.

Here is a comment from Doug Schryver of Sterling, IL o

 

Nick,

     I just wanted to comment on your post about Windmill Grass. One of my duties at the Park District in Sterling Illinois is Turf Management and I’ve read where the only herbicide that is recommended for Windmill Grass is Tenacity. I live in rural Whiteside County (northwest Illinois) and the soil in our neighborhood is very sandy and I’ve noticed a lot of Windmill Grass in the area. About three years ago most of our front yard was Windmill Grass and I decided to try to rid the yard of it. Each spring I usually would use a de-thatcher on the yard until I realized that it was actually just mixing the seed from the Windmill Grass into the soil and opening up the soil to the seed, so I no longer de-thatch. I used Tenacity on the yard in three sequential applications 7-10 days apart and had good luck controlling the weed. At that point our yard was very thin in that area so the rest of the season I would physically pull any Windmill Grass plants that I would see along with collecting any seed heads that would roll into the yard from a neighbor. That fall I overseeded the area with Barenbrug 50/50 RPR (Kentucky Blue/Regenerating Perennial Rye) at 7 #/m and I was able to establish a very thick carpet of turf. Now I mow at 3” height of cut, twice a week and I’m very diligent about pulling any kind of weed and collecting any seed heads when I see them and fertilizing on a regular schedule to keep a thick canopy of turf to prevent the Windmill Grass from gaining a foot hold. It was a lot of work for about a year but now I’m very happy with the result! Some of my neighbors have noticed and have asked how I got rid of that pesky weed.

                                Sincerely,

                                                Doug Schryver

 

 

 

 

 

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WINDMILL GRASS (Chloris verticillata)

September 19, 2013

 Nick Christians
September 19, 2013
nchris@iastate.edu

It's that time of year again when I'm getting calls and receiving pictures of a very annoying weed in lawns.  The weed is Windmill grass (Chloris verticillata), a warm-season grass that has thrived in the hot and dry period of late summer.  The seedheads are just now reaching full maturity and it is readily visible in dormant Kentucky bluegrass lawns.

It produces a lot of seed on the windmill-like seed head.  These seedheads will break loose when the seed is mature and it will roll across the lawn on windy days like a tumble weed and disperse the seed on surrounding areas.  Next year there will be more of it.

It is relatively new in central Iowa and we are still trying to figure out how to deal with it.

Roundup will kill it non-selectively, but it is a great seed producer and it will come back.  Tenacity (mesotrione) is labeled for it, but it will require persistence and you can expect new plants from seed in the spring.

Here are a few pictures that will help in identifying it.

This is a drawing of it from the Scotts Manuals on grass identification.
 

 

 

 

Seedhead found in a cemetery in Ames, Iowa.

 I took the next 3 pictures this morning just outside of Nevada, Iowa, in a dormant lawn in a park area.  The seedheads reach a height of 6 to 8 inches in some of the patches.

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IS IT CRABGRASS, BERMUDAGRASS, OR WINDMILL GRASS?

August 6, 2012

On July 3, I put up a post about Windmill grass (Chloris verticilatta) and on August 2 a post on Bermudagrass (Cynodon dactylon).  You will also find several posts on crabgrass (Digitaria spp) over the last two years.

Right now is early August, the seedheads from each of these species are visible in lawns.  I thought it would be a good time to get some pictures of the three species to help with identification.

Here is the seedhead of Windmill grass.  This warm-season grass has been moving into central Iowa and north for the past few years and there is quite a bit of it in Ames this yeas.  It branches off in all directions and rolls like a tumble weed when it breaks lose from the stem.  It is a little larger than most crabgrass seed heads.

Windmill grass forms a tight-knit mass of slolons in the lawn and at this time of year it is covered by seedheads.  (See picture 2)

Here is bermudagrass.  It also has a branching seedhead, but notice how each branch arises from the same point.   It is quite rare in central Iowa, although it looks like it may be expanding in this region.

This is crabgrass.   It is one of the most common weeds in Iowa.  Unlike the other two which are perennials, this one is an annual and has to come back from seed each year.  It is similar to bermudagrass, but notice how it branches off from varying areas along the stem.

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GOOD YEAR FOR WINDMILL GRASS

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.

 

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