I have a 3 gallon sprayer with Tenacity (~4oz/A rate) ready to go all season. My neighbor has creeping bentgrass patches from overseeding his yard with a blend containing it. I have to periodically spray the border to contain it. That and his poa triv that keeps wanting to cross over. Depending on what grass you are seeding, you may even be able to treat the creeping bentgrass while you are seeding. Just remember though that future Tenacity applications may be needed because the creeping bentgrass likely went to seed in those patches and you likely have a seedbank in those areas.

Great, thanks for the further info!

Also, can you please confirm how much I would put in my 1 gallon sprayer?

The tenacity label (that I found online) says 1 teaspoon per 2 gallon sprayer for spot applications, so am I really just using 1/2 teaspoon in my 1 gallon sprayer?

Also, it says to put 3 teaspons of "NIS adjuvant". What is that?

Finally, how soaked do get the lawn? Do you really drench it, or a lighter spray?

Yes, 1/2 teaspoon in a 1 gallon sprayer. NIS = non-ionic surfactant. I think you can get surfactant just about any garden product retailer--sometimes under the description "spreader sticker". I know many here use shampoo or dishwasher fluid. Spray it just like any herbicide really. It does not need a drench. For my purposes, your 1 gallon should treat 1000 sq ft.

Great, thanks again!

i should add that for dense patches with no desireable grasses within, i spray liberally, almost to the point of a drench.

Hi. I wanted to follow-up as I've gone ahead and applied Tenacity. As I walked my lawn I think I have more and more creeping bentgrass that I realized, so I sprayed pretty liberally in some dense patches, and less liberally in other areas. I guess I'll know in a week or two how I did... It's my understanding that I'll most likely need a 2nd treatment in 2-3 weeks. How do I know for certain, or should I just do it anyway, especially in the dense patches? Also, how/when do I proceed to aerate and overseed? Do I wait until after the 2nd application of Tenacity? And do I need to rake out the dead/dying grass (especially in the dense areas but maybe not in the lighter areas)? Or do I just aerate and overseed right over the dead/dying bentgrass? Thanks so much for all the help!

Was just reading a bit more on the tenacity label, and maybe I don't do a second application (at least not right away)? Perhaps I aerate/seed after a week or two, then wait 4 weeks after seeding for another application? Though it does say "Weed control with postemergence applications require a second application after 2 to 3 weeks."

Clearly I'm a bit confused by the label so any help is greatly appreciated.

I'm in CT and have mostly Fescue/Bluegrass, not worried about fine fescue.

Thanks!

Tenacity works differently from other herbicides. The bleaching effect does not indicate death. Ive never seen anything die with one Tenacity foliar application. You need bleaching for a prolonged period to get it to die. I would recommend 3 apps on creeping bentgrass. Sometimes it helps to blanket spray the first app over the entire lawn to identify undesirables.. Then bleached areas can be hit for repeat applications.

Thanks for the info. Can I aerate/seed/fertilize in the midst of doing all the applications? Should I avoid the dense areas until it fully does, then rake it away, then seed? Or just aerate/seed right over everything? Thanks again!

Fescue is more sensitive than blugrass to Tenacity. You want to avoid bleaching of your seedlings as much as possible. Maybe for successive applications avoid drenching. I overseed and treat at the same time. Also be aware that weed grasses are also germinating at this time. Anything that is very white, i assume to be weed.

Ok great. Thank you again. Also, do you eventually rake out the dead grass, or does it 'go away' on it's own over time?

As long as the seed can reach the soil, you do not have to remove the dead stuff.

Great, thanks again!

I used tenacity this past summer to help remove bentgrass. I made a YouTube video explaining my process. It took me two applications to kill mine off I didn’t go off the color of the grass but rather just raking it out to see how much of it had died off

https://youtu.be/QjHszetM8Dw

Thanks!

Would it be a waste a time to NOT completely (or at least mostly) rake out the dead/dying bentgrass, in the larger, 100% bent grass areas)?

mishmosh said above that it might not be necessary, but in doogie's video he completely removed it.

In the spots where I don't have too much, I might just let it be, figuring new seed will grow in as the bentgrass keeps dying, but for larger areas (10' in diameter) is it really highly recommended that I rake out much of the dead stuff and then seed?

I'd of course rather just aerate/seed over the larger areas (much easier), but if that's a waste of time and new grass won't grow well as it fights through the dying bentgrass, then I'll go ahead and rip out the bentgrass.

In either case I'm going to aerate the heck out of it (many, many passes with my tow behind aerator, which I know isn't as good as a 'real' aerator).

I'm getting a big shipment of seed today, and the weather is good for getting going on my seeding, so I was planning to aerate/seed tomorrow. If I have to take out all the bentgrass that will delay me, and then I'm busy for a few days, so I was really hoping to just aerate/seed w/o raking anything up.

Thanks for any further thoughts!

Great, thanks so much for the advice.

Sorry, quick follow-up; the Tenacity label says "Apply at grass seeding or close to seeding for best performance. Avoid spraying on newly germinated turfgrass plants. Wait until the newly germinated turf has been mowed two times or four weeks after emergence (whichever is longer) before making a postemergence application."

Does this mean that I can seed, and then spray tenacity after I seed (even a few days later) as long as the seeds haven't germinated yet? But I shouldn't wait more than a few days after seeding as some may germinate in 5-10 days, at which point I can't spray tenacity?

In other words, I last sprayed Tenacity 10 days ago, and I did an overseeding yesterday. I want to wait another 4 days for round two of Tenacity (so it'll be 2 weeks since round one), but I don't want to damage new seeds. I think I'm ok since nothing will have germinated within the next 4 days, correct?

Thank you!

Awesome, thanks again!

Hi. I wanted to follow-up concerning my not having removed all the bent grass. On 8/21 I sprayed Tenacity. On 8/29 I mowed lower than normal (though probably not as low as I should have had) and also weed-whacked the bent grass areas to get them even lower (though didn't completely remove as discussed in a post above. On 8/30 I aerated with a tow behind aerator (with a lot of weight on it and many, many passes), and overseeded and fertilized. On 9/1 I sprayed Tenacity again. I've noticed that the bent grass areas are either completely matted down (because they started to die and I went over it with the mower and/or all the watering has kept it matted down) or in some spots it's actually kept growing (though it is turning white and I guess starting to die). I'm concerned that my seeds are not going to be able to come up through it (if the seeds even managed to get down into the aeration holes). I regret not pulling it up more (or weed wacking it more) or something, to get it nearly gone. I'm still a few days away from when my seeds should germinate, but if start seeing them pop up in other areas, but not the bentgrass areas, is it too late to try and pull/rake/whatever more of the bentgrass and put more seed down? Or is it fine to do and it simply delays my next Tenacity (in at least several weeks' time) but an other week or so?

Thanks for your continued help!

as long as you had seed down before the dead stuff got matted down, i think you will be fine. people topdress with heavier, denser material than dead topgrowth. it'll be fine.

Great, thanks guys! I should know more in a few days. And, like you said, if it doesn't work, I'll overseed again in those areas.

Hey, another question (or two):

1. As it's been nearly a week since dose two of tenacity, should I be seeing vastly more white areas (or not necessarily just yet)? I feel like from the 1st dose on 8/21 to the 2nd dose on 9/1, that the bentgrass was really showing signs of being affected (i.e. starting to turn white), though parts have continued to grow back a bit. Again, it's not quite a week since dose 2, but I see no more whitening than before, and some spots still seem to be growing (or at least they grew at some point as they aren't as short as when I had cut them down with the weed wacker). That being said, there are spots where it must be dead/dying as it's brownish and really matted down (I wonder if I'm over watering those areas as the bentgrass seems to be soaked and that's helping it stay matted down).

One thing I read was "Foliage of treated weeds cease growth after application, then turn white (loss of chlorophyll) and death may take up to three weeks." My bentgrass hasn't (seemingly) fully ceased growing, and it's not nearly all white. It's only been 2.5 weeks since dose 1, so there's still time, but I was hoping it would be further along/more white by now. Am I just being too anxious?

2. For the parts that have been dying (and hopefully will die), what ultimately happens to it/should I do with it? Does it just 'fade away' (or fall out) as new grass hopefully grows in? Does eventual mowing help to get rid of it? Will I have to do any light raking to remove it...? Right now it's just a mix of some still alive bent grass, some whitening bent grass, some matted down bent grass... and I'm just not sure what to ultimately expect to happen.

Thanks as always and sorry for all the questions...

I have no trouble taking down bentgrass. It'll turn white then straw color after 2-3 treatments. However, if you have poa trivialis (roughstalk bluegrass) which likes the same conditions as creeping bentgrass, that may not turn fully white and may continue to grow. It will need multiple applications to fully take that down (if it does at all). Got any pictures?

And dead grass does not need to be raked up, it'll decompose just fine.

Thanks for the info. In another __ # of weeks I'll put another application (after my seeds grow in and a I mow a few times, correct?), and I'll absolutely take some pictures later today/tomorrow (no idea why I haven't done that yet as I always take pictures of these sorts of things...). I'll be back with pics soon. Thanks again.

Here are some pics: https://imgur.com/a/uf1fi

This was the easiest way for me to post them due to file sizes. The spots where you can see dirt is where I did some 'picking' of the dying bentgrass (ripped it up and tossed it in the woods). Other spots you can see where it's still somewhat alive, and other spots you can see where it is dying. You can't really see the matted down sports as those didn't come out great and I forgot to take better pics of those spots.

that's not bentgrass. looks like a ton of poa trivialis. i think you'd better rethink your gameplan. you may be better with a nuclear option.

Oh... Um, that doesn't sound good :( Is there any hope of the tenacity working or do you really think roundup(?) is the only solution? Could I just pull it all out like I was debating doing earlier? It's pretty easy to pull as it comes up in almost one big sheet because the roots are so shallow.

is there a reason for bentgrass/poa trivialis being there? looks rather shady and maybe wet. you will need a grass suited for the conditions first of all. then gameplans for eliminating what's there and finally, controlling weeds going forward. these are the questions that need answered.

poa trivialis will not reliably be controlled with Tenacity.

So the big patches in my back yard (the bigger areas in the pics) are a little shady (though normally during the summer they are pretty sunny, but lately the sun has been a little lower and behind the trees much of the day). There are some random spots in the front yard (the first pics in which it looked brighter are in the front yard). It's wet right now because I've been watering. Normally it's not that wet (especially the front yard). The back yard does tend to stay more moist (though never really wet I don't think) perhaps because my septic system is back there (although the big patches of whatever this is are not all that close to the septic). Also, this has never been an issue before this year. I've lived in the house 5 years now and have never seen this before (maybe tiny spots in the past that I never really thought about as they were so small and thought it was just different grass). This year though it really came out of nowhere and started quickly taking over. Also, my back yard is on a slight incline (not major, but slight) if that means anything.

All that being said, if you were me, what would you do? Another round of Tenacity to see if it's bentgrass? Go straight to glyphosate to fully kill whatever it is? then reseed with a sun/shade mix of seed?

Thanks again!

If you think TTTF/ ryegrass/ KBG can survive with the amount of sun there (which it sounds like it will), I'd round up the affected areas and reseed. A sun and shade mix may not work because creeping fescue may be the shade component and that would be injured by tenacity. Going forward you want to be able to use Tenacity to keep bentgrass and poa triv at bay, so you need desirable grass that is tolerant of Tenacity. I wouldn't trust Tenacity to eliminate what you have there. There is just too much and much of it is probably mature. Even after roundup, there are likely surviving stolons and also a seed bank to contend with.

Thanks again. Can you recommend a good seed that's a mix of TTTF/Rye/KBG? Also, is fine fescue in the same boat as creeping fescue (i.e. no good with tenacity)?

Also, same question I always ask; if I use glyphosate to kill it, do I need to rake it away? Or just aerate again and reseed? What would me steps be at this point? Glyphosate, aerate/seed in 2 weeks?

I've seen shade mixes that do not have fine fescues. They seem to have shade tolerant TTTF and KBG. I think that would be fine. You'll have to really inspect the bag label. Really, you can apply roundup and seed the same day. Creeping red fescue is a type of fine fescue and yes, will be damaged by Tenacity. Still would be good to apply Tenacity during the seeding process. The Scott's starter with crabgrass control is a good one as it has mesotrione (Tenacity) in it. Apply that at seeding and hopefully keep poa annua, creeping bent and (hopefully) poa triv from establishing with the new grass.

I still have a bad feeling that there is a reason poa triv has overrun the areas in your pics. It is hard to stop it if conditions allow it to grossly overcompete desirable grass. That is usually shade and moisture. If it's not as shady as you say, perhaps you are watering the area too much?

As long as seed can reach the soil, no need to rake up the dead stuff.

Thanks again for the info. I'll take a loot at some seed mixes. It's definitely not normally so shady (normally the sun hits our back yard around 11 AM and hovers over it until sundown. But the past few weeks it's shifted and is behind the trees much of the day. I don't normally water a lot at all (only lately due to overseeding). I guess I'll try roundup, reseeding, scott's starter and see what happens...

Thanks. Mine problem grass doesn't stand up as well as that in the photo. So I guess I do have the poa, not the bent grass :(

You may have some bentgrass in there but most of what's in your pics is poa trivialis. Of this I am completely sure.

Hi. So it's now been 21 days since round 1 of tenacity and 10 days since round 2. I haven't seen any recent movement in color, etc (and certainly nothing like the pure white in your pics above). Should I give it any more time or just kill the bad spots with glyphosate and reseed again in a couple of days? If I do glyphosate and reseed, is it as simple as mowing the spots really low, spraying, raking in seed and maybe some topsoil (as I don't want to aerate again), and water? Anything different that I should do based on the glyphosate?

Update: I had a local lawn care company come out to give me an estimate on glyphosating/reseeding. They said that the grass in question is not anything bad, and all they see is normal fescue coming in (from my recent overreseeding). This doesn't explain what was there before, unless I really did manage to kill it all off and it's really just new grass coming in. I'm assuming they weren't lying as it would have been in their interest to say it was something bad, so I would pay them to kill it/reseed it. But they said it was all good. They said it's lighter green because it's new, but it should turn darker. So I guess for now I'm doing nothing and we'll see what happens going forward...

Hi all. So I think you were all correct and it is poa triv. I had another company just come out and they agree that it's poa triv.

Assuming I need to go nuclear, what is a good game plan (the company wanted to round up now soon and do it again a few times over the spring/summer, and then seed in the fall)?

I prefer to do this myself, so do I indeed do it now, and keep doing it periodically over the summer, to make sure it's entirely dead (or as dead as I can get it) and then reseed in the fall? Could I go nuclear once or twice and then spot seed (so it doesn't look so awful)? Can I just go nuclear late summer and then reseed)?

I definitely want to do this right, but I also don't want an awful dead/patchy lawn (which actually might be better than the bright green spots now that I think about it).

Thanks again!

Thanks. I thought I had read somewhere that it could take many/many applications, as there could/would be underground feeders that would be hard to kill with just 1-2 applications. That being said, I guess no harm in doing a couple and then seeding. Worse case I wasted time seeding and have to kill it all off again (if the poa comes back)... Right?

What is your tolerance for a dead, straw-colored lawn? It would be ideal to kill it off before summer hits and reseed in the fall. Do not let summer hit when the poa triv will go dormant and be tough to kill with glyphosate. If you have a lot of poa triv, you are best to just nuke the entire thing. It's tough to eradicate though and is a source of contamination in lesser quality grass seed. There is also undoubtedly a seed bank in the soil so you for sure will have to use Tenacity at seeding. But I will say it again, Tenacity does not reliably control poa triv--both existing AND at seeding. I find that it is best to round up the small patches that show up every year once you get an outbreak under control. In KBG (very tolerant of Tenacity), you can keep it at bay with multiple low dose applications for a few months.

Unfortunately I have a lot. It's going to look awful, but I know there's no other choice :(

How soon can I reseed after using glyphosate? Thanks.

I'm still a little gun shy as far as glyphosating right now, but I went ahead and applied some Tenacity mixed with 2,4-D to various spots on my lawn (to kill regular weeds and maybe slow down the poa). I didn't really think it would do much on the poa, but some spots are really dying (some have just turned really, really light, but others are actually browning). Are they perhaps something else mixed in with the poa triv?

just fyi, many consider tenacity + triclopyr to be the definitive tankmix.