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View Full Version : Pre-emergent in St. Augustine


villagegreenlandscape
08-23-2007, 02:40 PM
I've had trouble with my St. Aug lawns getting rescue grass in the winter and a little crab grass in the spring. I was told never to apply a pre-emergent to St. Augustine but the lawns started looking really bad so I applied a light dose of Pre-M and TW - big mistake. I wound up with large dead patches in the lawns. Any suggestions?

ampeg76
08-23-2007, 05:08 PM
pre's are fine on st. augustine, timing is everything, whoever said you couldn't does not know his ass from a hole in the ground

DSTC
08-23-2007, 05:28 PM
pre's are fine on st. augustine, timing is everything, whoever said you couldn't does not know his ass from a hole in the ground

Totally agree. You just have to read labels and make sure that you are using pre-m's labeled for St. Augustine in your state. We use Atrazine and Barricade here in GA for Pre-M in the spring before transition.

If you can't use Atrazine, then you can probably safely use Gallery for broadleaf Pre-M. Could also use Ronstar, Pendulum, or Dimension for crabgrass pre-m. All depends on how much you wanna spend and what results you wanna get.

There could be many reasons for the appearance in the turf that you describe. St Augustine often has chinch bug problems. It is also susceptible to Gray leaf spot, Brown patch, and Take all Patch. It is not very tolerant of 2-4-D or very many Post-emergent herbicides, so you have to be careful there too. I would look for other problems before blaming the Pre-m herbicide, unless you used a product that St. Augustine doesn't tolerate well. In that case, just change the product.

villagegreenlandscape
08-23-2007, 05:33 PM
It could easily have been the 3way. I think it was a combination of really dry, cold weather and the herbicide - I was seeing yards next to mine with the same shade/sun etc looking fine and mine had apparent freeze damage and good watering. My area has a mix of bermuda and St. Augustine, is there a good pre-m that works well for crab grass and rescue for both types, cost being a factor if possible?

RAlmaroad
08-23-2007, 07:09 PM
It could easily have been the 3way. I think it was a combination of really dry, cold weather and the herbicide - I was seeing yards next to mine with the same shade/sun etc looking fine and mine had apparent freeze damage and good watering. My area has a mix of bermuda and St. Augustine, is there a good pre-m that works well for crab grass and rescue for both types, cost being a factor if possible?

That's the problem--I know of NO Three-Way that's safe for St. Augustine. Plus, the heat activates and strengthens the stuff. Flood it, flood it, flood it. Roy

LawnDawg65
08-23-2007, 07:18 PM
It could easily have been the 3way. I think it was a combination of really dry, cold weather and the herbicide - I was seeing yards next to mine with the same shade/sun etc looking fine and mine had apparent freeze damage and good watering. My area has a mix of bermuda and St. Augustine, is there a good pre-m that works well for crab grass and rescue for both types, cost being a factor if possible?

It was the 3 way, I use simazine in the fall and dimension in the spring, luckily I have 2 tanks and can mix the 3 way in the 1 for bermuda, but it can def. hurt the st. aug. if mixed at full rate. Thanks, Chris www.candbcustomlawns.com

ampeg76
08-23-2007, 09:12 PM
actually 3-way is fine on st augustine, its about temps once again, i use the lowest rate spiked with the lowest rate of quicksliver and can smoke most weeds out there:)

i currently use lesco's 3-way, the new label has a lower dicamba concentration, but have used the other label with no issues


i would not spray it in houston before late november or after late march

if ric would chime in he could give you the skinny with all the scientific data

cheers

gregory
08-23-2007, 10:57 PM
i know he told me he uses three way with no problem..i think he told me he uses it at half rate from whats printed on the label i want to say .75oz/1000 i could be worng with that number i can't remember what he said...i talked to him yesterday and told me he was out of town and has no net service so it might be a few days befreo he stops by...

DSTC
08-24-2007, 02:33 PM
actually 3-way is fine on st augustine, its about temps once again, i use the lowest rate spiked with the lowest rate of quicksliver and can smoke most weeds out there:)

i currently use lesco's 3-way, the new label has a lower dicamba concentration, but have used the other label with no issues


i would not spray it in houston before late november or after late march

if ric would chime in he could give you the skinny with all the scientific data

cheers


It's not that all St. Augustine is intolerant to 2-4-D. The problem is that some cultivars are sensitive to it. Temperature is also a concern. The problem is this......

Have you ever asked a homeowner what type of cultivar of St. Augustine they have? I promise you that over 90% of them will NOT be able to tell you.

Personally, I don't take that chance. If they have "Floratam" and someone puts 2-4-D on it, bye bye grass. There are other cultivars as well that are sensitive, but that is the one listed on Trimec classics label. Here is a copy of it.

http://www.pbigordon.com/pdfs/TrimecClassic-SL.pdf

Another thing to consider is that if a Three way is used on a cultivar of St. Augustine that is is not labeled for, then that means it's being sprayed out of label and brings up a whole other set of liability issues.

Personally, I just play it safe and NEVER take the chance of spraying anything with 2-4-D on St Augy.

RAlmaroad
08-24-2007, 02:55 PM
Gordon's also makes Weed Killer with Trimec that centers around St. Augustine and Centipede. I've read that label over and over again and still not totally convinced that it is safe. I might use it at 1/3 strength and not worry too much but then probably not especially now when it is deathly hot. 100 degrees in Tn and we're cool compare to friends in Georgia and Flordia.