Help with grassy bright green weed?

noremorse63April 19, 2013

Hi, I really need help in determining what kind of weed/grass this is and then how to kill it. A little background is that we just bought this house last year and it was a short sale so it had tons of weeds and crabgrass. After doing a good job of controlling them this year--very few dandelions, just some henbit now--I have these bright green, fast growing spots in the yard. Since I just got the house, I have been overseeding with straight Kentucky Blue grass, hoping to fill in some dead spots in the yard. I have attached some pictures. I need advice on what the best course of action is since it appears to be spreading. I have no idea what grass is currently in--really dark green though. Thanks-D

Oh, I am in North Eastern Maryland, it says Zone 7 when I did the calculator.

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That looks like poa annua to me. Tenacity may help control it. It goes to seed heads soon--so bag your grass. Using a pre-emergent starting late summer can help reduce it next season.

    Bookmark   April 19, 2013 at 2:18PM
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Thanks, that is what I was leaning towards after reading these forums. I always cut the lawn before it has a chance to get to seeds and I actually don't even have bagger --it is about a 1 acre yard.

SO what is the best pre-emergent? Do I use granules, or spray?

Finally, where do I get these good products? I have even tried the local feeds stores and while they have some different brands than the big boxes, they don't have tenacity or certainty or anything like that? Thanks again

    Bookmark   April 19, 2013 at 2:22PM
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Tenacity and Certanty are post emergents and can be purchased on the internet if unavailable locally. I think attacking with a pre- emergent is more effective and less expensive route to take.. And there is alway RU. Lol
As far as a pre-emergent to use in late summer to reduce next years crop of poa, any granular will do--Dimension, Halts, Evade etc.
Good luck.

    Bookmark   April 19, 2013 at 5:12PM
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It looks like poa trivialis, not poa annua. Unfortunately it is very hard to control. Tenacity isn't very effective against it, and I have heard that even using Round Up is no guarantee that it will be killed permanently. It's a perennial, so preemergents aren't really any use. Certainty is a very strong herbicide that can harm the turfgrass as well as undesirable weeds and I think it isn't for use on cool season turf anymore. The good news is that it will go dormant in the summer. When it does, use a thatch rake to pull up the stolons and throw them away. The ones you miss will green up again in the fall.

    Bookmark   April 20, 2013 at 1:06AM
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Hold on before treating! That's not Poa Annua (annual bluegrass), it's Poa Pratensis. The spikelet and seed heads of Poa Annua or Poa Trivialis have a maximum height of 4"-5" and the stems are way to thick to be Poa Annua. Before reading your post completely, I was going to tell you that the Poa Pratensis may have been mixed in with your seed, particularly if it was a cheaper seed. Then, I read your post thoroughly and realized that you planted Kentucky Bluegrass and there's the result. Poa Pratensis is the scientific name for Kentucky Bluegrass. The surrounding turf is a higher quality Fescue, which appears to be a Tall Fescue variety. The higher quality fescues are darker and slower growing than Kentucky Bluegrass. The color difference will diminish as the bluegrass matures.

I have the same problem in my own personal yard at this time, because the water authority replaced my water meter and seeded the area around it with KBG, which grows twice as fast as the Tall Fescue cultivars I have in the lawn.

Fortunately, as it matures the difference will be less evident, but by all means stop seeding with the KBG. Also, definitely don't use Certainty. Certainty is labelled for sedges and Poa Annua or Poa Trivialis, but it is also labelled to kill Fescue (which is your lawn type). As for the Tenacity, it's fine for Poa Annua suppression in Fescue, but again that isn't the weed in the picture and KBG is perfectly tolerant of Tenacity.

I added a link with a picture of Annual Bluegrass in Bermuda to give you an idea of how it looks in the lawn and to go with the picture of the sprig of Annual Bluegrass that I pulled as an example. If you do a good search for Poa Pratensis I'm sure you'll find images that show grass very similar to what you're seeing in your lawn. One sure-proof way of knowing is to check for rhizome activity, which is why you're seeing dense patches like the one in your picture. KBG produces determinate rhizomes, while Annual Bluegrass doesn't produce rhizomes at all.

Here is a link that might be useful:

    Bookmark   April 20, 2013 at 1:15AM
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Quick edit there, I just noticed that I lumped Poa Trivialis in with the Poa Annua on the max height. This was a mistake. Certainty controls both varieties, but the Poa Trivialis matures to a height more similar to Kentucky Bluegrass. The Poa Annua is the much lower grower, usually reaching it's maximum height of 5" just before it dies off in mid to late Spring.

    Bookmark   April 20, 2013 at 1:26AM
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Thank you all for the advice. I do have some other kinds of grassy weeds too--they are smaller with whitish tips/seed heads, not quite sure. If I remember correctly from last year, this faster growing bright green stuff seems to die off in the summer, so I will then treat with a pre-emergence if I can find any at the big box stores,I can't even find regular Scotts Halts--it is always the weed/feed with Halts in it but not the straight stuff. Then I will re-seed this fall with a tall fescue.

Are there any recommendations as to where to get a good quality seed instead of Lowes/Home Depot? I really like the dark dark green and want to keep it and spread it to the weak spots.

Thanks again for the help, this has been driving me crazy!--D

    Bookmark   April 20, 2013 at 7:34AM
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Serenitylawnservice's advice is incorrect. The bright green grass you have pictured is not Poa pratensis, commonly called Kentucky bluegrass. Kentucky bluegrass generally grows slower than tall fescue and perennial rye, and is typically dark green, not the light green as shown in your pictures. Kentucky bluegrass can and does go to seed, but it is usually once a year, and lasts a few weeks. Those seeds are not viable, as they require months to harden and mature. The fast growing light green stuff (poa trivialis) is a perennial that goes dormant in the summer (turns brown and disappears) but will return with cooler weather in the fall. Poa trivialis at lawn heights rarely develops seed heads, but it spreads via stolons. The shorter light green patches with lots of whitish seed heads is poa annua. Poa annua is an annual (typically, although perennial varieties exist). It should die off this summer, but the seeds will lie in wait for cooler weather in late summer/early fall. They will germinate when soil temps fall below a threshold value, but not grow to maturity. The will wait till spring to continue their growth, and seed production (some poa annua germinates in spring and seeds in fall, but it is usually a small amount). If you want to overseed your lawn there are many good seed sellers on the internet that sell the newest varieties of turfgrass. For tall fescue The Hogan Company carries a lot of great cultivars. Bullseye is one of the best available. If you want to over seed with Kentucky bluegrass you can use Hogan, but there are others as well like Williams Lawn Seed (ask for Dennis), Pawnee Buttes, Newsom Seed, L.D. Oliver, etc. Kentucky bluegrass has many different cultivars, and classes. For MD you should pick ones that do well in your area. A good all around cultivar that tests very well is Bewitched. Hope this helps.

    Bookmark   April 20, 2013 at 10:22AM
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Proper diagnosis is important in forming a plan.

To know for sure identify a few grass parts and compare. I included a link with a diagram to help you to know what to look for on the plant. In the picture (I tried zooming in to be sure, but I couldn't see it well enough) I can see that the plant parts necessary for ID are all there. So the question is Rough Bluegrass (Poa Trivialis) or Kentucky Bluegrass (Poa Pratensis).

1) Ligule- Trivialis has a 4-6 mm membranous ligule; Pratensis has a Short membranous ligule

2) Auricle- If it has an auricle we're both wrong as this is absent on bluegrass cultivars

3) Sheath- Trivialis has an onion-skin appearance

4) Collar- Pratensis has a narrow collar

5) Mid-rib- Pratensis will have a prominent mid-rib

6) Growth habit- Trivialis will produce stolons, which remain above ground. Pratensis spreads with rhizome activity, which generally remain below the surface.

Here is a link that might be useful: Parts of a grass plant

    Bookmark   April 20, 2013 at 11:14AM
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I try to be nice on these forums, but I disregard that rule when someone posts misinformation and a link to their company with every post. So let's get a few things straight. From what I can tell, you operate a lawn service company in the Atlanta area. Anyone in the lawn service business who can't tell the difference between Kentucky bluegrass and poa trivialis, or who doesn't know the difference, really shouldn't be offering advice. Anyone who thinks that the water authority would put down KBG seed in the Atlanta area to reseed an area is ignorant (it is unlikely that any town authority would use straight KBG to reseed). This statement you wrote: "The surrounding turf is a higher quality Fescue, which appears to be a Tall Fescue variety. The higher quality fescues are darker and slower growing than Kentucky Bluegrass." is incorrect, as I mentioned earlier. While it is not the rule for every single KBG cultivar, Kentucky bluegrass is almost always as dark as tall fescue, and slower growing. It also is slow to establish, and would look nothing like the picture the OP provided. Also, newly seeded KBG would not show much in the way of rhizome activity, and checking for activity is not a very practical method of identification.

As this is a forum, you can post whatever you want, but you are doing a disservice to it by posting incorrect information in combination with trying to drum up new customers for your business. I'm not sure why the moderators have allowed you to continue this practice, hopefully they will catch on to your charade.

    Bookmark   April 20, 2013 at 1:03PM
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I don't serve the Maryland area, so I don't understand the assumption that you've made regarding drumming up business. I'm exclusive to Atlanta. I do regularly answer questions, because I enjoy the profession. If it was drumming up business, I would be exclusive to GA posts, which I'm not. Not to mention that advising someone on DIY methods isn't exactly a marketing strategy most service companies are eager to adopt. Perhaps if I was trying to sell a product, that logic would make sense. The one occasion that I helped a local poster, I recommended a couple of landscapers and vendors that I've seen do work in the area. There again, no benefit to me, so your conclusion about my motivation is incorrect.

As for which variety of Bluegrass, I mainly responded to this post when I saw the Certainty reference to prevent the original poster from investing in a high dollar herbicide that would damage their turf. Based on the fact that the Kentucky bluegrass was recently planted, I still suspect that it is the grass they're seeing as it would be less mature and brighter in color than the surrounding established turf. The only way to properly identify it is to inspect the plant parts that I described above. I am more focused on providing tips that help the homeowner make a proper identification, than I am on gambling with a guess, or making it a contest of who's the best troubleshooter. So, if they inspect the plant parts and find it to be Rough Bluegrass, your diagnosis was correct and they'll know what they're dealing with.

    Bookmark   April 20, 2013 at 1:38PM
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Then why do you post "Here is a link that might be helpful" at the bottom of most of your posts (the first ones of the thread), which link right to your website's home page? How is that helpful? Regardless of where you are, it is still advertising. I don't read posts only from Connecticut, and just because a poster is in MD, doesn't mean the thread isn't read by someone in the Atlanta area. If you want to be helpful, that's fine, just don't include a link to your business home page.

Your misinformation is another topic altogether. It's one thing that you give out wrong information, it's a lot worse when you are in the business. That makes you look ignorant. While young Kentucky bluegrass is generally a bit lighter when newly germinated, it is nothing like what's shown in the OP's pic in color, or growth habit, and it certainly wouldn't outgrow an established tall fescue lawn. I am not gambling on a guess, my opinion is based on what I see and what I know about grass. It could very well be that the weed in question is not poa trivialis, but from the information given, it's the most probable one. KBG is the least probable.

    Bookmark   April 20, 2013 at 2:16PM
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Actually, the "here is a link.." is automated by gardenweb any time you add a link. As a habit, I prefer to give people context about where the answer is coming from. As you can see, I don't hide the business name or web site. It allows readers to decide for themselves whether or not I'm credible. On occasion I refer people to their extension agent, which is a service that is often under utilized. I do recognize that in a world that is driven by bottom lines, it is hard to imagine giving information with no gain, but I've been doing this sense I left the corporate green industry. My first class as an independent was teaching landscapers how to get started in the certification process for applying pesticides in Georgia (laws, study materials, etc.). I taught the class for free. I still get questions from other businesses on a weekly basis. I even compare notes with some of my former corporate colleagues from time to time (I occasionally had the opportunity to do field testing, so even though I'm out of it now, I still get questions on newer products).

As for the question on the KBG vs. Rough BG, I wasn't being absolute in my answer, and I didn't see your post until I posted mine (I think we were probably typing them out at the same time, I'm just more long-winded). I even considered the possibility that it might be Kentucky 31 that was planted, which is sometimes confused as Kentucky Bluegrass rather than Tall Fescue. The main goal of the post wasn't a definitive distinction, but mainly to make sure the homeowner did not make the mistake of applying Certainty. Certainty is sometimes confused with the label for Manage, which was once the leader in sedge control. However, unlike Manage, Certainty will kill Tall Fescue. What's more, if it is a variety of KBG or K31, an herbicide isn't really necessary, as it will blend much more effectively once it matures.

I hope this serves to dispel some of your assumptions, but that's totally up to you at this point.

    Bookmark   April 20, 2013 at 11:46PM
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Well I have waited longer than normal to moe and the bright grass is kind of going to seed. I guess it doesn't really matter what it is since I plan on putting down a good pre-emergent as soon as it goes dormant in the summer. I have learned my lesson though using the cheap crap grass preventers from Lowes/HD, I thought they were all the same, I had no idea that other versions would also control the grassy weeds. I still have a long way to go--even after all the weed feed, crabgrass preventers, etc, I still have henbit and dandalions too! Not as bad as last year, but still there.

I was looking at the Hi Yield granules--any opinion on those?

Thanks for the information on the grass--I had no idea what kind it was, I just really like the deep dark green and since that was how KBG was described on the bag, I thought that was what I should over seed with.

    Bookmark   April 22, 2013 at 6:31PM
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Kentucky bluegrass is dark green, that bright green grass is not Kentucky bluegrass. Do a little googling and I bet you find it using a grassy weed ID key. Good luck.

    Bookmark   April 22, 2013 at 8:06PM
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dchall_san_antonio(8 San Antonio)

noremorse, we discourage granular herbicides. We prefer spot spraying with liquid herbicides designed for the target plant. Grassy weeds and broadleaf weeds (dandelion and henbit) are different and require different herbicides. For broadleaf weeds a 2-4,d product like Weed-b-gone works well and will not affect your grass. For grassy weeds they also make Grass-b-gone. That stuff will kill all the grass it lands on (at least theoretically). So if you spray it into that yellow-green mess, it will kill the fescue and KBG underneath. The KBG will recover but the fescue will not.

I'd like to thank tiemco and serenity for carrying on one of the most civil disagreements I've seen here in forever.

    Bookmark   April 22, 2013 at 10:37PM
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You can find better pre-emergents at suppliers like John Deere/ Lesco (they've merged) than the home improvement stores. I agree with dchall, in my own findings granular pre-emergents don't perform as well as the liquid. The field testing that that the manufacturers site (so take that with a grain of salt) suggest that they perform about the same. If you're after grassy weeds, such as crabgrass, dimension is a great pre-em. If you're seeing a lot of both grassy and broadleaf, Prodiamine is a good alternative. The advantage with Prodiamine is that it is much cheaper to manufacture and has a number of generic versions. The 2-4D that Dchall mentioned is definitely a safe alternative in cool-season grasses for broadleaf weeds. Another, if you have trouble with crabgrass this season is Quinclorac. Quinclorac has the major advantage of being safe on Fescue even when it has just been seeded. To my knowledge it is the only herbicide that can boast that. If you mix it with a methylated seed oil, you have a good crabgrass control. The only odd exception is crabgrass that is in the intermediate stage, between newly emerged and mature quinclorac won't give any control during this period.

As for the bright green grass, it isn't uncommon when you've been seeding so see color differences. Tiemco is correct about KBG being a dark green when it matures. There is a definite possibility that what you've seeded has come up much darker than what was there before. I ran across this today with a Fescue lawn that I seeded last Fall. The cheaper Fescue that was in the lawn looked much brighter than the cultivars that I used which included Speedway, Davinci and Blackwatch. So it's entirely possible, that the brighter colored grass was a lower quality Fescue, such as K31 that was there before. All the same, make sure that you don't over-do the seeding, which can lead to over-crowding and cause die-back or pythium blight in the up-coming months. Also, it's good to use a blend. There are a number of improved varieties of both bluegrass and fescue on the market today, which offer advantages over the older cultivars. For example, you can buy a mix of thermal blue, which is 10% bluegrass and the other 90% is made up of 3 different Fescue cultivars. It's highly drought tolerant and disease resistant.

Either way, good luck and thanks for sharpening our skills with your question.

    Bookmark   April 23, 2013 at 1:43AM
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Siduron is also safe on new seed. It's the active ingredient in Scott's Step 1, and I can attest to it's safety as I used it on mine without issue. Mine was obviously granular, but I'm sure there is a liquid-based Siduron product.

    Bookmark   April 24, 2013 at 7:54AM
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I have read most of the reply's and it seems to be disagreement on what it is. The picture appears to be what I have. The grass is dark green and the light green appears as one plant or a group. When the lawn is cut the light green is about an inch longer after the first day. I have asked Scotts to get rid of it and they spray and the weed turns white and goes but it is not gone for ever. I am looking for the same thing scott uses that is sold on the market. I have not seen it go dormant. Are their any sugguestions?

    Bookmark   August 30, 2013 at 1:11PM
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I'm in Minnesota and this stiff, bright green, faster-growing reed-like grass is in part of my yard that is most wet.

They have a Stalky stem and grow in 2-3-4 blade little clumps, It has a center vein. I've found a couple hidden in my garden and they can get quite tall. (12 inches?)

It is NUTSEDGE! Mine It is not Blue Grass or any of these other names.

Ortho makes a spray for it that works quite well, but may kill grass around it. Since mine is now controlled, as a result of sodding, I just pull them out from root as they pop up. Spray is called NUTSEDGE Spray.

Good luck.

    Bookmark   July 28, 2014 at 7:43PM
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Adding Photo of NUTSEDGE

    Bookmark   July 28, 2014 at 7:50PM
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The original pic is not nutsedge! It definitely looks like POA trivialis to me. Believe me, I had my share of nutsedge and that is not it. I have tried tenacity on the Trivialis but it always seems to come back. It is a horrible grassy weed and hope that some better treatment options will be availae in the future for it.

    Bookmark   October 9, 2014 at 3:34PM
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