Tumbling Nimblewill

WENDY WOLPERT

Dig in with the Mas­ter Gardeners

It has been a slow, cold spring in Delaware County. Lawns all across the county lay dor­mant well into April, wait­ing for the right con­di­tions to break dor­mancy and begin to grow. Finally, we’re recov­er­ing from the one-two punch of last year’s hot, dry, long sum­mer and cold, snowy, long win­ter. Our lawns are finally turn­ing green and we can see what lived through the tough weather.

A lot of lawns around the county had brown patches of dead-looking grass this spring. In some cases, these were in areas that seemed green and lush when the rest of the lawn was really strug­gling last year. In drought-stricken sum­mers, when your turf is really strug­gling, “warm sea­son” and annual grassy weeds some­times get a chance to thrive. Crab­grass, fox­tail, quack­grass, and nim­blewill were all invad­ing and enjoy­ing the heat and lack of com­pe­ti­tion last sum­mer. As home­own­ers tried to beat the heat with extra water­ing, nim­blewill got its ideal con­di­tions of mois­ture and heat while the blue­grass, rye­grass and fes­cue was pro­tect­ing itself by lying dormant.

Sim­ply dri­ving across the county this spring, I saw many big, tan patches of nim­blewill (Muh­len­ber­gia schre­beri). “Nim­ble Will” is a mat-forming, warm sea­son, peren­nial grass. Like the com­mon names of many weeds, he gets a nick­name based on his growth habit. Over the course of the sea­son, this nim­ble grass will prac­ti­cally som­er­sault across a lawn if con­di­tions are right.

Nim­blewill will start by seed. As a warm-season grass, it likes to start in a warmer soil tem­per­a­ture than our lawns, which are cool-season grasses. In the early part of its life, the blades of nim­blewill are short and upright. This early growth is a lush green, so it blends right in with the rest of the grass in your lawn. This time of year, when you mow at least once a week, you often won’t see new patches of it at all.

How­ever, as the plant matures the growth pat­tern changes. The stems bend over and lay on the ground. These stems will actu­ally take root and begin to send up new, shorter leaves. Before you know it, you have a dense, low grow­ing mat of this grass form­ing. The mature leaves are a gray-green color. It gets eas­ier to see, the older the plant becomes. These patches will be a dis­tinc­tive tan color from the first hard frost until well into late spring.

Many peo­ple mis­take this tan patch in their lawn for signs of grub dam­age in the early spring. To test for grub dam­age, the old “field test” is to grasp the grass and give a lit­tle tug. If it comes up eas­ily, like a car­pet, the wis­dom is that you might have grubs. This advice is cer­tainly a good way to check in July or August, when grub dam­age com­bines with heat and drought stress to kill por­tions of the lawn. Test­ing for grubs in this way is best done before the first hard frost in the fall, before warm-season grasses go dor­mant for the winter.

If dor­mant nim­blewill got estab­lished last year, it would have formed a dense mat. That mat of grass has a weak, fibrous root sys­tem. Once it gets cold, this grass pulls up very eas­ily, espe­cially when dor­mant. So, if you go out and tug on a patch of this grassy weed while it is still brown, you’ll get hand­fuls of it. Large, mat-like areas will come out of the ground with lit­tle effort. Just because a mat of grass is brown and gives you no resis­tance does not mean you have grubs, espe­cially if you saw no sign of prob­lems in that area last year. If it was green until frost, it is much more likely a grassy weed.

For more infor­ma­tion, visit oardc.ohio-state.edu/weedguide/singlerecord.asp?id=90 or ohioline.osu.edu/hyg-fact/4000/4002.html.

Wendy Wolpert is an OSU Exten­sion Delaware County Mas­ter Gar­dener Volunteer.

Posted by Master Gardener on May 21 2011. You can follow any responses to this entry through the RSS Feed. Comments can be made below.