Post Emergent Weed Killer for Large Lawns

7,646 Views | 18 Replies | Last: 4 yr ago by MTTANK
ForeverAg
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Sooooooo we did not put down a pre emergent in the winter and our lawn is wild with various weeds. We hoped the winter would kill off some of them however we were wrong. One challenge we have is our lawn is about 1.5 acres or so. What is the best way to handle large scale weed killing on St. Augustine?

Location - Houston Area
1.5 Acres
St Augustine Grass
Ill try to upload a photo of the various weeds.
FatZilla
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24D on a mild temp day in the 70s? Can get cheap large bottles of concentrate at tractor supply.
GBMont3
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Yeah 24D for broadleaf weeds, horses are out of the barn for grassy winter weeds most likely though I find pulling them therapeutic. Time to get preemergent down for spring weeds and almost time to fertilize. Spring green up will beat out the remaining grassy stuff from winter.
JSKolache
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Pull all you can by hand and treat earlier next year. The hardest thing to pull by hand is clover, everything else is pretty easy
El_duderino
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They're gonna die off when temps warm up anyways, so no use in spraying a post emergent for winter weeds now. Just get down a pre e ASAP if not already since it's late for the Houston area and then just don't forget in the fall.
Funky Winkerbean
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Get a hose end broadleaf weed control from a box store. Add a little dishwashing soap beforehand. May need a follow up application after 2 weeks.
ForeverAg
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El_duderino said:

They're gonna die off when temps warm up anyways, so no use in spraying a post emergent for winter weeds now. Just get down a pre e ASAP if not already since it's late for the Houston area and then just don't forget in the fall.
I hoped the weeds we had before the winter would have died off in the winter...those are still around. I feel like I need to take action now.

Do yall have a good preemergent you would recommend?
mosdefn14
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My guys are putting down the spring pre-emergent treatment this week. Obviously put some down in the fall too. I have nothing green yet, but everything other than crabgrass is easy to kill once it's in the 80s.

Pre-emergent, whatever Ewing/Site One have in stock if you can buy from them. If not, Halts
El_duderino
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ForeverAg said:

El_duderino said:

They're gonna die off when temps warm up anyways, so no use in spraying a post emergent for winter weeds now. Just get down a pre e ASAP if not already since it's late for the Houston area and then just don't forget in the fall.
I hoped the weeds we had before the winter would have died off in the winter...those are still around. I feel like I need to take action now.

Do yall have a good preemergent you would recommend?

Do you know what the weeds are? As far as pre emergent, it depends. I assume you just have a push spreader and it needs to be granular?
water turkey
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The only thing growing this time of year is weeds. Once the grass starts growing and the heat starts killing the weeds, it will be better.

I use the Nito Phos with Barricade as active ingredient as pre emergent.

It will be very expensive to cover 1.5 in pre emergent.
Cromagnum
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water turkey said:

The only thing growing this time of year is weeds. Once the grass starts growing and the heat starts killing the weeds, it will be better.

I use the Nito Phos with Barricade as active ingredient as pre emergent.

It will be very expensive to cover 1.5 in pre emergent.


Not as bad as you think. You can buy a tow-behind tank sprayer like an Ironton and then buy prodiamine powder from DoMyOwn and it's way cheaper than buying 5-6 sacks of granules, especially over time.
El_duderino
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I think he meant granular pre-e is expensive for that much yard. I went the tank sprayer route as well. 31 gallon northstar sprayer and use a combo of prodiamine/simazine. $150 for the pre-e and they'll last me around 3-4 years.
water turkey
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Quote:

Not as bad as you think. You can buy a tow-behind tank sprayer like an Ironton and then buy prodiamine powder from DoMyOwn and it's way cheaper than buying 5-6 sacks of granules, especially over time.
That's good because fertilizer and everything else is through the roof this year.....
ForeverAg
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Attached are a few of the weeds throughout the entire lawn


Thisguy1
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The grassy weeds with white seed heads are poa. It will die off when it warms up but nothing you can do about it now in st augustine. Best way to help that is a preemergent in the fall.
El_duderino
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The top one is lawn burweed. Those suckers hurt. I used simazine as a second pre e in addition to prodiamine and got rid of about 90% of it the first time I used it this past fall. Here's a helpful article on it.
https://www.lsuagcenter.com/profiles/aiverson/articles/page1548367150290
1997aggies
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Your main problem here is, without a doubt, Poa Annua!
The best killer for this particular weed is a product called Image. Keep in mind that this weed will eventually die off once the summer heat arrives. When I have a few spots of Poa Annua following an application of pre emergent I tend to kill it early with Image. It may take 2-3 weeks for the Poa Annua to be completely killed off but it works great!
FincAg
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Start mowing now! I've putted on poa, not the greatest but better than hardpan.
MTTANK
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Went to apply some nitro phos barricade pre emergent, and figured out I did not have any left in the shed. I have always ordered it online. About to go on vacation, so no time to order some now. All I could find local was barricade mixed with potash, went ahead used it against my better judgement. Will my yard be a wasteland? Here is what I bought: https://www.lowes.com/pd/Lesco-LESCO-Stonewall-Crabgrass-Preventer-0-0-7/5001213041
GIG 'EM
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