Paul, I'll take a stab at this because I hate to see a question go unanswered this long. I've never used a pre emergent and don't seem to have much trouble with poa annua or crabgrass (probably because conditions are not good for seed germination here).

From what I understand about the pre emergents, they work by creating a sort of barrier. So if you core aerate after applying a pre emergent, you negate the effect of the pre-m.

I don't think it makes any difference how long you wait after aerating to apply the pre-m.

I wouldn't bother breaking up the cores.

Thanks BP.

was your dimension gran or lig? Also I would advise Prograss (which I bought 2.5 g) since it will help more then dimension.

I would wait a week or so since sometimes it will burn roots if liquid.

Thanks Buy_25,

It was Lesco 0-0-7 granular, I applied at the "program 3" rate and plan to do the same again, since I have enough left over to do that. But I will look into the prograss too.

You mean wait a week after aerating?

Thanks again,
Paul

if you plugged (aerating) wait a week then apply. The liq gets too the roots much faster then the gran stuff. I have 2.5 gallons of prograss since I am in the same boat as you. I have 5 gallon of dimension 2EC, other pre-m's and now prograss. the POA is going to go down....I hope.

Hi Paulinct -

When you say you are going to apply another pre-emergent in August to prevent POA - when does the poa actually germinate?

I have some small patches and would love to get rid of it. I know it's easier said than done, but I figured I'd try and start by educating myself!

I am also battling Veronica. Despite killing it off every year with WeedBGone, it comes back more and more each year. I need to understand better the germination cycle that one, too!

But anyway - insight on POA germination is greatly appreciated!

Hi Graswhisperer,

This is all new to me too this year - my pre-renovation lawn was so choked with weeds that I never even noticed it before, but now it really stands out, just begging to be killed off...

Poa Annua germinates mostly in late summer/early fall, but there can be some spring germination also. So unless I read some better advice I'm planning to put the Dimension down around August 15, and then again next March, earlier than I ordinarily would for crabgrass control. This schedule screws up my planned fall aeration, and probably any spring aeration too, so I think I will just take care of the really bad spots with a manual aerator this year over the summer, here and there, whenever I think the grass can take it, and then stop a week before putting down the Dimension on Buy_25's advice.

Unfortunately, there are apparently oxymoronic perennial varieties of "annual" bluegrass out there, and a pre-emergent like Dimension won't kill them. That's why Buy_25 is recommending Prograss (ethofumesate), which I gather is a post-emergent control with some pre-emergent effectiveness as well, at least if I have read that right. But apparently that can be expensive. I need to look into that further, but below is a link on a discussion from earlier this year.

Good luck! What a rotten weed. As difficult as spring seedings can be, I may never seed in the fall again.

Here is a link that might be useful: ethofumesate discussion

For me, I am applying Liquid Dimension on Sept 1 (1.5 oz per 1,000sq/ft) and then again in May (after Pre-m 3.3 or Drive 75). The Prograss will be sprayed on 8-15 and then 2 more times in 4 weeks intervals (then spring). I think of POA like Crabgrass. Dim, drive 75, Image etc will not kill it but prevent it. Prograss is the "killer".

My 2.5 gallons of Prograss was expensive but it is far cheaper then killing old grass, re-seeding etc.

{{gwi:102337}}

PS. The problem with the link above is it is illegal to apply these products to a lawn. They are for Sugar Beets. Plus instructions are poor. There is a new product this is tested to be WAY better then prograss but still in testing.

Buy 25 you are certainly loaded for bear! I like your idea a lot and will try to get another lawn nut neighbor with Poa (that came with his sod!) to go in with me on some prograss.

One thing, reading up on the stuff I came across statements to the effect that we don't know why it works, but that since it has some effect on the waxy coating of the leaves it may cause the plants to dessicate over winter. Have you found anything more precise on how it works? Just curious.

Thanks,
Paul

Well, when you fellows find out please let me know. I've had that crap for 6-7 years now (came in with several loads of topsoil along with that dadgum bermuda), and seem to keep it somewhat in check but not gone. I've priced that Prograss and I don't think I can handle it.

I'd be interested in the other item that's in testing though. Is there a name associated with it yet?