# POA and Pre Emergent?



## Jonslawn (Apr 30, 2021)

Hello Lawn family!

So this past spring and summer I have noticed on my lawn and many others in my neighborhood POA throughout my lawn and others. I have been putting in alot of work on my lawn and filling spots with over seeding the last couple years now but have some spots on my lawn with this POA now and it looks awful now that it is dormant and the rest of my lawn is doing great actually!

I am planning to do aerating probably Mid august as I am in Ontario, then overseeding and top dressing with soil and peat moss. I have seen a couple times on here the best option is to use a pre emergent in the fall so I am just curious if anyone has had any experience with doing this. I do have Tenacity so would it hurt to aerate, overseed and then spray my lawn with tenacity then top dress to take care of my POA and as well thicken up my lawn?

Doing a complete burn off of my lawn is out of the question, just looking for another way to fix this issue!

Thanks!


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## Lumalux (Aug 23, 2019)

I want to hear about this, too. I've always had some poa triv in areas of my shady backyard, but this year it is much worse. I have been manually removing the stuff from the turf (it's like pulling hair from a tub drain). Will this remove it or will it keep coming back?


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## Virginiagal (Apr 24, 2017)

Skip the overseeding and concentrate on fertilizing well starting late summer and into the fall. You have KBG which spreads and should fill in bare spots. It is hard to overseed KBG anyway as it takes so long to germinate and the existing grass outcompetes the seedlings. Use a regular preemergent, like Prodiamine, in late summer/early fall when the soil temperatures falls below 70. That will protect against poa annua. Poa triv is a perennial, whereas poa annua is an annual, so preemergent will not protect against poa triv.


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## Jonslawn (Apr 30, 2021)

Virginiagal said:


> Skip the overseeding and concentrate on fertilizing well starting late summer and into the fall. You have KBG which spreads and should fill in bare spots. It is hard to overseed KBG anyway as it takes so long to germinate and the existing grass outcompetes the seedlings. Use a regular preemergent, like Prodiamine, in late summer/early fall when the soil temperatures falls below 70. That will protect against poa annua. Poa triv is a perennial, whereas poa annua is an annual, so preemergent will not protect against poa triv.


Awesome thanks man that is great! I have started to correct my fertilizing program as I just got back a soil sample but if I don't know how much is actually KBG in some spots where I do have patches and I am going to overseed what is my option for the prodiamine? Should I wait until late fall when the new seedlings have grown in or should I do prodiamine first and wait a couple weeks to seed?


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## Virginiagal (Apr 24, 2017)

You. cannot seed after putting down Prodiamine. If you seed and put down Prodiamine in late fall, many poa will be germinating before then. It's your choice: battle poa with preemergent in late summer/early fall or overseed. I suppose another choice is preemergent in the fall, seed in the spring but then you miss the chance to use preemergent to battle crabgrass and other summer weeds.

Info on herbicide delays after seeding:
https://turf.purdue.edu/herbicide-delays-after-seeding/


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## M32075 (May 9, 2019)

If you just have spots of areas that need to be seeded and the majority of the lawn is nice and healthy you can spot seed the bad areas. Drop your pre m early water it in good or wait for a good rain to activate it. Your bald areas scratch the dirt up really good break the pre m barrier in the soil. Put down some seed step on it for good seed soil contact then handful of peat moss or even a little potting soil and step on again. It works if you have just a bunch of areas that need to be fixed. I will say trying to rid your lawn of POA by using preM is a few years process with my experience.


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## stevehollx (Apr 8, 2020)

I agree with prodiamine in early fall and not overseeding. Let the KBG spread in the fall and spring. Prodiamine in the fall will block the Poa A next year, and then if you are still thin next fall, overseed since you wont have as many Poa A seeding due to blocking it this fall from growing.

If bare spots really bother you still in the spring, put some KBG+rye in those spots in the spring and apply pre-em skipping those spots.


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## stevehollx (Apr 8, 2020)

Lumalux said:


> I want to hear about this, too. I've always had some poa triv in areas of my shady backyard, but this year it is much worse. I have been manually removing the stuff from the turf (it's like pulling hair from a tub drain). Will this remove it or will it keep coming back?


If you have Triv you have a different problem. I'm surprised Triv isn't toasted in RVA at this point. It is a headache where you have to accept a not-perfect kill and not-perfect seeding time either. Sorry this is a bit of a brain dump, but I've spent about a year fighting an infestation of it.

You have to gylpho Triv while it is growing or it will return and spread larger than before each time; fall or spring gly-summer won't be too effective. There is a study that shows Spring gly is more than double as effective (IIIRC 80% improved? than in the fall.

For you, I would apply glypho to it when it starts growing actively in Sep or early Oct, and then put late seed down on those spots late Oct since you can probably get by with a late seed in VA that will still take hold over the late season and warmer winter. Some Triv will come back in the spring, hit it with gly again then and keep the fertilizer in the spring off it. You can reseed then too though you gotta get on it early (15-mar in CLT or maybe even a week or two earlier) (and overspray past the edges to ensure you can get it killed so you dont need to add more rounds-also extend overseed past the fringe you gly too) and get seed down to take well before summer heat.

In spring seeding, if you are time crunched before summer heat (I'd say any less than 6 wks before 90F), throw seed right over the second gly app so it germinates while the Triv continues to die. I did that in some spots and seed came right up as the Triv continued to die.

A lot prefer to dig it out after 1 or 2 apps of gly before seeding. But depends how much you have if this is manageable. I had to treat a 1000' section of Triv this spring so I did 2x gly, seed over the top, and then still caught some stuff at the fringes that I gly'd and threw seed over the top on the same day (which those edges didn't survive summer by this point already).

Also, spray or dig out about 9" past what you see or you will regret it as it grows at the edge still after all this work. I accidentally discovered a cool trick where if you spray tenacity over the spot when you seed and extend out with a fringe, it is easy to see if any Triv is returning and you can nuke and/or dig those spots again. If you are overseeing this fall in the rest of the yard and using Tenacity at seed down that will help you identify your Triv target spots for kill (you will just defer or reapply seed to the Triv spots you gly as it would stagger seeding of those spots 3-4 weeks after your overseed/Tenacity of the rest of the lawn).

Another cool trick to find Triv in the spring is to just apply iron and it will stick right out. Then apply tenacity + gly when killing and anything you miss will light up at about the time you are seeding. You can use this trick in late fall too and find it. If I saw small spots I'd prolly gly and dormant seed it and assess spring strategy based on it.

Hopefully smaller and smaller patches every year…


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## Jonslawn (Apr 30, 2021)

Virginiagal said:


> You. cannot seed after putting down Prodiamine. If you seed and put down Prodiamine in late fall, many poa will be germinating before then. It's your choice: battle poa with preemergent in late summer/early fall or overseed. I suppose another choice is preemergent in the fall, seed in the spring but then you miss the chance to use preemergent to battle crabgrass and other summer weeds.
> 
> Info on herbicide delays after seeding:
> https://turf.purdue.edu/herbicide-delays-after-seeding/


Okay I think you have me sold on prodiamine for the end of summer/early fall. Just cut my lawn and it's lush now but a lot of brown dead stocks of poa in their as well which makes it look kinda so so! Would like to fix that first and try to be patient!

I have a backpack sprayer so what would you recommend my mixing being per 1000sq' and is it a one time app this season before winter or should I drop two apps down before frost?

Also if I have some small spots that are bare should I avoid spraying those and that's where I toss down some fresh soil, seed and some peat moss this fall to get that to fill in or just wait until spring? Or are you saying as well to toss down more prodiamine come spring as well and wait until next fall to overseed?

Thanks sorry for the questions just want to do the right process!


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## Jonslawn (Apr 30, 2021)

M32075 said:


> If you just have spots of areas that need to be seeded and the majority of the lawn is nice and healthy you can spot seed the bad areas. Drop your pre m early water it in good or wait for a good rain to activate it. Your bald areas scratch the dirt up really good break the pre m barrier in the soil. Put down some seed step on it for good seed soil contact then handful of peat moss or even a little potting soil and step on again. It works if you have just a bunch of areas that need to be fixed. I will say trying to rid your lawn of POA by using preM is a few years process with my experience.


Awesome cool thanks a lot for that info!
So spray entire lawn with prodiamine and then come back with my hand cultivator and break the soil and toss down maybe some new soil, seed and peat moss even though their is prodiamine under it?


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## Virginiagal (Apr 24, 2017)

As for how much to use, read the directions on the herbicide. It will tell you how many months protection you get from such and such amount. The spring application is to protect against summer weeds and goes down when the forsythia blooms. It's best to have continuous coverage. M32075 has a good idea if you have distinct areas that need seed. The seed may or may not germinate but it's not going to harm anything to try. You could also skip the preemergent for those particular spots. You could also grow some KBG in pots and plant them in those areas. I'm not convinced you need to overseed at all. Maybe you should show us pictures.


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## Jonslawn (Apr 30, 2021)

Virginiagal said:


> As for how much to use, read the directions on the herbicide. It will tell you how many months protection you get from such and such amount. The spring application is to protect against summer weeds and goes down when the forsythia blooms. It's best to have continuous coverage. M32075 has a good idea if you have distinct areas that need seed. The seed may or may not germinate but it's not going to harm anything to try. You could also skip the preemergent for those particular spots. You could also grow some KBG in pots and plant them in those areas. I'm not convinced you need to overseed at all. Maybe you should show us pictures.


Okay that's great, I read a bit of the label before and it didn't seem to cover some of the weeds I have in my lawn up here in Ontario like white clover, dandelion. I do have the odd funny looking grass that's a lighter green and thicker blades grows faster than the rest of the lawn but very few spots of that which by sounds of it the prodiamine would target that stuff and the little bits of crab grass I have! Would be great if it works against dandelion's as well and the clover so I don't have to spot spray as much next summer.

As for photos just got to work for the night so I will snap some pics tomorrow morning when I get home I just cut the lawn before work so it should show up the brown spots with POA. I have pulled some out by hand where its a small patch but I don't have the time to go through my entire lawn pulling out each piece. I did notice a few days ago some new POA coming in as we have had cooler weather for the last 7-10 days and a lot of rain so probably brought the soil temps down below 70 or near it my guess???

That's a good idea with the pots as well. I actually have three on the go in the front window with three different types of grass seed that I have put down in the last couple of years. This spring I laid down a bag of a TTTF with some perennial and chewing fescue. I had bad infestation of Chinch bugs last summer and that's why I have always lost my lawn but I got some Bifen I/T for that and have not seen a single one this summer so hoping I wont have to worry about loosing the lawn this year long as I stay on top of irrigation and rainfall. 
My front lawn faces south so I have always had a lot of sun and no shade on the front of my lawn and I think that's why the POA is coming in because I have not really had a thick lawn in the past as I am just getting more into it this year and last fall. I did aerate my lawn this spring, last fall and spring so I have seen some reviews saying that can cause issues with weeds. I feel my soil is doing better this summer so probably wont even do it this fall and let the lawn do its thing.


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## Jonslawn (Apr 30, 2021)

I just found a prodiamine calculator and their is quite the difference on amount to use between KBG and TTTF, Figure go in between the two amounts? Its not going to kill my KBG if I average the two differences?


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## 440mag (Jan 29, 2018)

Virginiagal said:


> ….
> Info on herbicide delays after seeding:
> https://turf.purdue.edu/herbicide-delays-after-seeding/


What an awesome reference - Thank YOU! :thumbup:


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## Virginiagal (Apr 24, 2017)

KBG and rye have less tolerance for Prodiamine than tttf. If you have KBG and rye and tttf, use the rate for KBG and rye. If your soil temperature in the winter is such that nothing will germinate, you can have a shorter period of protection for the fall application.

You don't seem to be sure what kind of grass you have. Maybe this will be helpful:
https://extension.psu.edu/the-cool-season-turfgrasses-identification


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## Jonslawn (Apr 30, 2021)

Virginiagal said:


> KBG and rye have less tolerance for Prodiamine than tttf. If you have KBG and rye and tttf, use the rate for KBG and rye. If your soil temperature in the winter is such that nothing will germinate, you can have a shorter period of protection for the fall application.
> 
> You don't seem to be sure what kind of grass you have. Maybe this will be helpful:
> https://extension.psu.edu/the-cool-season-turfgrasses-identification


That's what I was thinking go with the lower limits and well I am in Ontario so we normally have snow and frost from December-mid March and plus the odd snow storm before or after! 
So your saying do like a 4 month app instead of a 6 If that's the case?

And honestly I am not sure. It was sod 4 years ago when we moved in but they laid it end of July and it was stressed to the max! Then we had chinch bugs for two summers and I wasn't aware I just thought it was drought! So lost most of the front yard and laid about 70 bags of soil last spring an seeded the front with 50/50kbg and perennial rye grass but some may have grown back from under the soil I laid which I don't know what that is. As for the rest of my lawn an backyard I overseeded with the same blend on top of whatever the sod was. An this spring before finding this forum and really learning more I threw down a 40%TTTF 30%perennial and 20 red fescue 10 chewing fescue as they said it would help for pests and drought! I like the idea of being a mix of KBG and TTTF! I like the thickness and larger blades in my backyard but not sure what it actually is! I just took a bunch of photos to show you the POA throughout but maybe you can tell what the grass is from the photos! I'll take a read of that link you sent but I just worked all night so probably won't be able to process it fully haha!


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## Jonslawn (Apr 30, 2021)

Photos 1,4,9 are the backyard not sure why it got mixed up and photo 3 is some of that taller lighter green grass weed I have a little of throughout the yard just a few patches


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## Virginiagal (Apr 24, 2017)

Yes, 4 months should be good enough.

I see no reason to overseed. You have full coverage already. The seed would just be outcompeted by the existing grass. You would be trying to water for new seed and that could lead to fungal issues for the existing grass. Concentrate on fertilizer instead.


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## Jonslawn (Apr 30, 2021)

Virginiagal said:


> Yes, 4 months should be good enough.
> 
> I see no reason to overseed. You have full coverage already. The seed would just be outcompeted by the existing grass. You would be trying to water for new seed and that could lead to fungal issues for the existing grass. Concentrate on fertilizer instead.


Okay awesome, I will give that a shot than! And the fertilizer I am focussing on now. I got my soil test back and my lawn is pretty deficient in Phosphorous, Potassium, and Magnesium so I bought a 5-20-20 fertilizer I'm going to start applying and I was told Epsom salt for the Magnesium but I also have a high pH level out front 7.8 and 7.3 in the backyard so I need to figure that out because I can't find any elemental sulphur or at least an amount I need to bring it down without crushing my wallet!


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## Virginiagal (Apr 24, 2017)

Don't feet about the pH or about not finding elemental sulfur. It's possible the sulfur wouldn't even work. Many people just live with a high pH. The. Ingest problems are that phosphorus and iron get bound up and unavailable to the grass. You can use foliar iron. Have you read this?
https://thelawnforum.com/viewtopic.php?t=15165


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## Jonslawn (Apr 30, 2021)

Virginiagal said:


> Don't feet about the pH or about not finding elemental sulfur. It's possible the sulfur wouldn't even work. Many people just live with a high pH. The. Ingest problems are that phosphorus and iron get bound up and unavailable to the grass. You can use foliar iron. Have you read this?
> https://thelawnforum.com/viewtopic.php?t=15165


Yes! I read that before and was trying to find it the other night! I actually bought some FAS and have applied it twice back in the spring but I thought it was only an appearance product and had no effect on the lawns health but if your saying it would benefit me what are your thoughts on me spraying some down tonight on the lawn an watering it in tomorrow morning but was also going to lay down my 5-20-20 this evening too am quickly water it in or could I lay down both an water in the morning? It's suppose to "feel like" 88 tomorrow but pure clouds all day and rain on Tuesday early morning. Storms most of the week but hot


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## M32075 (May 9, 2019)

One thing you don't need is a over seed


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## Jonslawn (Apr 30, 2021)

M32075 said:


> One thing you don't need is a over seed


Thanks man I am starting to realize that too! As I walked the lawn today I'm not noticing too many spots that need touch up other then where their is POA but hopefully fall weather helps with those spots more!


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## Virginiagal (Apr 24, 2017)

I would hold off on both until cooler weather. Summer is not a good time to fertilize cool season grass. When summer heats starts to break (maybe August for you?) you can start fertilizing for the fall.


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## Virginiagal (Apr 24, 2017)

The recommended amounts in the soil test are for a year. You don't have to put them down in just a few months. For the fall you will need to supplement the 5-20-20 with a nitrogen only fertilizer to get enough nitrogen. 5 lb of 5-20-20 gives you .25 lb of N, 1 lb of P, and 1 lb of K. That's great for P and K but you need .75 lb of N from somewhere else (general rule is no more than 1 lb of a nutrient per 1000 sq ft per month in an appropriate time to fertilize, fall being the very best time for nitrogen fertilization). If you are subject to snow mold, maybe just do one application of the 5-20-20 and save the rest for the spring, as potassium fertilization in the fall has been associated with increased snow mold,


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## Jonslawn (Apr 30, 2021)

Virginiagal said:


> The recommended amounts in the soil test are for a year. You don't have to put them down in just a few months. For the fall you will need to supplement the 5-20-20 with a nitrogen only fertilizer to get enough nitrogen. 5 lb of 5-20-20 gives you .25 lb of N, 1 lb of P, and 1 lb of K. That's great for P and K but you need .75 lb of N from somewhere else (general rule is no more than 1 lb of a nutrient per 1000 sq ft per month in an appropriate time to fertilize, fall being the very best time for nitrogen fertilization). If you are subject to snow mold, maybe just do one application of the 5-20-20 and save the rest for the spring, as potassium fertilization in the fall has been associated with increased snow mold,


So I should probably only put down some of what those results are saying since spring is less than a year away? An when you said to focus On fertilizing for rest of the summer/fall should I just maybe do one app of the 5-20-20 and then monthly Urea until end of October maybe? I also have some FAS left should I apply some of that each month on top of UREA or does it have to be one or the other?

I had put down 3 or 4 apps of 9-2-2 2%iron organic fertilizer this spring/ early summer and it seemed to feed the lawn really well but yA my results show low phosphorous and potassium so figured the 5-20-20 would bring those back up


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## Virginiagal (Apr 24, 2017)

You can do an app of 5-20-20 and at the same time do some urea. And then continue with urea for the fall. FAS can be done at the same time as other fertilizer or done by itself. In the spring if you want to continue with the organic fertilizer, you can do both. Adjust the rates, if need be, so you don't go over 1 lb per 1000 sq ft per month for a nutrient. Maybe aim for .5 lb per 1000 sq ft of nitrogen then. Don't want excessive. nitrogen in the spring. Push it in the fall instead.


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## davegravy (Jul 25, 2019)

@Jonslawn you never stated which Poa you think you are dealing with here. Triv? Annua? Pratensis 😛?

Have you actually visually ID'd the grass or are you assuming? The treatment strategy varies drastically depending which one it is, and it may not be Poa at all - it could be over or under watering, or fungal, or another grassy weed.


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## Lawn Noob (Jul 26, 2020)

I heard an interesting take on the Grass Factor podcast. The topic was prodiamine -resistant poa. Apparently it is rampant in the south, if I understood Matt properly. Maybe going down with spectacle personally next week.


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