Which one you use is pretty much up to you--those that are listed as suppressing grasses are the ones that will work on P. annua (which is most of them).

How long to wait after use for seeding is going to vary widely. With Dimension, it could be as short as a month or as long as three. With Prodiamine (Barricade), it could be as short as two months....or as long as a year.

So if you're overseeding in fall, it's pretty much already too late to use a pre-emergent this year--except Tupersan, which can be used with some grasses (I'm not sure about rye), and Tenacity, which suppresses out P. annua and P. trivialis to a point for about a month after application.

The easy rule is, if seeding, use Tenacity or Tupersan. If not seeding, use whatever you want.

This year, it sounds like you'll need to tolerate the weeds, kill them using an herbicide before seeding, and then control mechanically for the remainder of fall. Next year you can get down a pre-emergent shield early in the year. Make sure to keep it active through crabgrass season, which is from the point soil temperatures rise over about sixty until they fall under sixty again (seventy is often quoted, but I find it has no trouble sprouting a little cooler).

morpheuspa - thanks so much for your response! I'm a little confused, though, as to why you mention it being too late already for putting down a pre-m. The directions for Barricade, for example, indicate that it should be placed on a lawn 6-8 weeks before overseeding with Rye in Arizona (see page 15 on link below).

I won't be overseeding until the middle of Oct, which gives me 10 weeks from now. What am I missing?

Here is a link that might be useful: Barricade Link

This post was edited by amoncur on Wed, Jul 30, 14 at 11:06

I can't speak on the timing in relation to overseeding. I had poa annual and used dimesion. It completely eliminated it

That's a nice light app of Barricade, so it should be fine. Typical me, I was thinking of our seeding time which is only 2 weeks away.

I use the stuff from the big bottle of granules, 65% active ingredient, and usually shoot for 9 months of protection from Barricade--but most people don't do that.

>>I can't speak on the timing in relation to overseeding. I had poa annual and used dimesion. It completely eliminated it

At least it'll help! I probably got 95% control, which is more than good enough for me. The other 5% I take out with Tenacity.

Okay, thanks! Any recommendation on prep before applying the pre-m? For example, should I cut the grass right before applying? Apply in evening? Mid day?

>>Any recommendation on prep before applying the pre-m?

Makes no difference, really. In granule form, don't mow with the collection bag on (if you ever do) until it's watered in.

I've been doing some research on pre emergents and I've settled on Tenacity, unless anybody has a good reason not to use it. I like it because, if I understand it correctly, it works as both a pre and post emergent, and I can seed fescue anytime after application.

The only thing I don't like about it is that it's not granular. I'm worried about applying it evenly. I don't want to overapply or miss areas. Any advice or tips on this? (Or perhaps an alternative product with the same traits that does come as a granular)

***Okay, thanks! Any recommendation on prep before applying the pre-m? For example, should I cut the grass right before applying? Apply in evening? Mid day?***

Morpheus eluded to this a little bit but apply before a rain.

>>I've been doing some research on pre emergents and I've settled on Tenacity, unless anybody has a good reason not to use it.

If the expense doesn't bother you, go for it. Not that it's really all that expensive, I'm still using the small bottle I bought three years ago. It should last another five, and doesn't seem to weaken with age so far.

It's a very short-term pre-emergent, however! One month. After that, reapplication will be required. Since your new sprouts will be too new for any other pre-emergent that touches the Poa genus, Tenacity would be your only choice.

>>The only thing I don't like about it is that it's not granular. I'm worried about applying it evenly. I don't want to overapply or miss areas. Any advice or tips on this? (Or perhaps an alternative product with the same traits that does come as a granular)

Tenacity is currently rather unique, although rumor has it that there are others in the pipeline (not yet available to us common folk). To my knowledge, there is no solid form as of yet.

Great care when spraying is your only choice here. If you miss, you miss--Tenacity is also good as a post-emergent, so you always have the option and opportunity to kill it after it sprouts.

I have the best luck killing P, annua and P. trivialis with Tenacity either moderately late in fall (October for me) or moderately late in spring (May). It may not actually kill it outright, but it weakens it very, very badly just before conditions get bad (winter or summer). That takes it right out.

Ok, you've convinced me it's not a good pre emergent option due to the 1 month lifespan. I'm unhappy with WeedBGon for crabgrass control...very weak. I'm looking for something to knock it down now that won't impact fescue germination 3-4 weeks from now. Any recommendations?

Regarding pre emergents, I'm back to square one between Barricade, Dimension, and Snapshot DG. I haven't seen Snapshot mentioned anywhere on here...is it new? I like the granular aspect of it...

>> I'm unhappy with WeedBGon for crabgrass control...very weak.

For pre-emergent? It has no pre-M component, so it's actually not effective there at all.

For killing it, if you're finding it weak you can try to add 1 tsp of Turbo Spreader Sticker to the mix. If you're going to use your existing mix very shortly (within a week or so), you can use 1 tsp any liquid soap in the mix.

If you're making your own from concentrate (I do), the hardness of the water impacts the effectiveness--the harder the water, the less effective it'll be. I'm fortunate that my water is naturally very soft.

The soap will help get around that.

>>Ok, you've convinced me it's not a good pre emergent option due to the 1 month lifespan.

It's great for seeding, and one of a very small number of herbicides effective on P. annua and P, trivialis. Not to mention nutsedge and thistle. Don't count it out of your arsenal entirely.

>>Regarding pre emergents, I'm back to square one between Barricade, Dimension, and Snapshot DG. I haven't seen Snapshot mentioned anywhere on here...is it new? I like the granular aspect of it...

No recommendation, I'm afraid, given your circumstances--except to tolerate things this year, do the best you can, and get a good pre-emergent shield down next year.

Sorry, I meant WeedBGon for post emergent. I shouldn't have assumed you could read my mind and know the exact situation I was talking about. I'm still battling the crabgrass I've mentioned in other threads...pulling it is way too time consuming because it never stops.

I've never mixed my own WeedBGon, I just buy the kind ready to spray. I'm getting just as sick of it for weed control as I did Scotts for fertilizer...

>>I've never mixed my own WeedBGon, I just buy the kind ready to spray. I'm getting just as sick of it for weed control as I did Scotts for fertilizer...

While it's cheaper if you mix it yourself, I get being sick of it.

Just this evening I discovered another piece of crabgrass growing in the garden...fortunately, I can use Round Up there as it grew in the stone runoff area.

That's not an option in your grass. However, there are certainly enough crabgrass killers out there that you can try another with a different active ingredient. Sometimes one just works better than the others, even though somebody else will report the exact opposite.

On the very up side, with a good pre-emergent layer next year, this is the last year you need to deal with it. And the height of the season for crabgrass is right now. It only gets better as we move into the lower sunlight and lower temperatures of late summer.

Drive works well on crabgrass. Also for pre-M before seeding-Barricade will work. You can apply 8 weeks prior to seeding and the seed will germinate. This is done regularly on Bermuda grass in the golf industry.

Just mind that you put down the Barricade at the 8 week level and not at a higher one (my Barricade application is shot at 9 months of protection).

At this point? Solar summer is almost over (it ends August fifth when sunlight levels are no longer at their highest levels). Crabgrass is still going to germinate for as long as soil temps are above 60-70 degrees, but it's not going to be quite as energetic as it was in July.

To everything there is a season and all that. Crabgrass' isn't coming to an end yet, but it's slowing down a little.

Yes, I'm trying to encourage you. :-) Your annoyance level with this will slowly drop--just as mine is about to do with the nutsedge!