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My yard is about 6 years old (new house). When we put the yard in, the seed was equal parts Fescue, Rye, and Kentucky Bluegrass. We live in NE Ohio.

About 2-3 years ago, we started getting these bright green (almost neon in color) patches all over the yard. We don't do too much for fertilizer, put down Scott's Winterguard in the fall and the Scott's Spring (yellow bag) in the late spring. But that's about all we do.

Any idea what this is and how to go about getting rid of them?

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UPDATE: Close up pictures to help determine the kind of grass.

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    are those patches of grass dead? or just changed in colour? (Sorry cant tell from photo) – Seanland Jun 23 '11 at 14:56
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    It could be a dog that pees over there. – baka Jun 23 '11 at 17:32
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    Do you live near a golf course or play golf often? Could be poa or bentgrass - I have a similar issue. If this is the case, best way to get rid of it is to dig it out & replace with sod. – Brian Jun 23 '11 at 18:10
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    Dog marks (and I guess this would have to be a bitch) are usually a yellow dead grass 'fertilizer burn' surrounded by a halo of enhanced growth. – winwaed Jun 23 '11 at 18:18
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    Years later, the patches still exist, but are must less prevalent. I did nothing special to treat this. The rest of the yard seems to be slowly taking it back over. – Mike Ohlsen Jun 1 '17 at 12:42
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It is difficult to be sure, without the help of a close-up, but if the patches look like this or this, the problem is likely to be Poa Trivialis.

Poa trivialis is a perennial grass that spreads by stolons forming light green patches in the turf. It is best adapted to shady, moist, or overwatered sites, and because of this, it often appears in mixtures with Kentucky bluegrass and perennial ryegrass recommended for shady areas. Two theories persist about how Poa trivialis is introduced to a turf stand. Some believe that Poa trivialis grows naturally over most of the world and Poa trivialis seeds or stolons can germinate after lying dormant for many years, thus contaminating a turf stand. Others believe that it is introduced as a contaminant in turf seed and seed producers growers have since self-imposed Poa trivialis growing and shipping restrictions to help prevent this.

Control

There is no selective control of Poa trivialis today, though scientists are trying to develop one. Nonselective control with glyphosate or glufosinate followed by reseeding may offer the best chance of control.

Article by Purdue University

Apparently, its growth can be discouraged by deep but infrequent watering, good drainage, mowing 3" or above and heavy traffic.

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    this seems very likely. i will get a close up and post – Mike Ohlsen Jun 23 '11 at 18:41
  • uupdated post with closer pics – Mike Ohlsen Jul 1 '11 at 16:13
3

yea, it's a different type of grass. if you let it grow, you'll see it grows similar to onion grass or a beach grass. If you want to get rid of it, let it grow, which will help you identify it, pull it out, and reseed.

I deal with this type of grass as well. I deal with it little by little, pulling it out, and dropping some soil, and reseeding.

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I have exactly the same thing in my shaded and often damp back yard in the Buffalo/Niagara region. I also used a fescue/rye/blue grass mix when originally planted 4 year ago, if that makes any difference.

Since I live about 100 yds. from a golf course fairway I suspect it is Poa or another bent grass as others have suggested. I'll probably dig it out and reseed during the fall growing period.

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It's possible you might have dropped some fertilizer when you were spreading it. This can cause certain grasses to thrive and others to die off.

(Comments added to the question after this answer makes it appear this isn't the case. This is a common reason for patches to look different, however, so I'll leave the answer here in case some future person comes along with a similar problem.)

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You might consider Tenacity (http://www.greencastonline.com/product/tenacity-herbicide/overview)> It will kill lots of grassy weeds without killing the good turf.

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It could be creeping bent grass. If it comes up in a sheet when you pull it, it’s creeping bent grass. Can’t be sure but it looks like some spots in my lawn.

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