Crabgrass in St. Augustine

Crabgrass in St. Augustine

SAGBELS – posted 17 June 2004 11:53

I am new to and live in NE florida. I resodded the better part of my lawn early this spring. I hired a local outfit to maintain the pest and fertilizer/weed control. I am getting invaded by crabgrass. I am pulling as much as I can, but I can’t keep up. My question is, am I wrong to expect these guys to keep the crabgrass in check? I hear the chemical of choice was withdrawn from residential use. Is there any alternative? Also, I am begining to see some Torpedo show up – Same question applies.. Thanks for your time.

ted – posted 17 June 2004 16:30

post some pics- crabgrass is the most overused, generic term for weeds. weed id is crucial for selecting the correct product.

SAGBELS – posted 17 June 2004 20:25

ted,Not sure how to add a photo. I’d be happy to e-mail you a photo, if your interested. Thanks. sagbels@bellsouth.net

seed – posted 17 June 2004 20:38


If you email me a picture, I’ll post it on this site.

Phil, editor@turfgrass.com

seed – posted 18 June 2004 07:58

Thanks, the photo is here:

Alex_in_FL – posted 19 June 2004 06:24

Image works on crabgrass. Most companies just use atrazine on St. Augustine because Image is more expensive.

Tell the company to do something about the crab grass. If they say they can’t then tell them to spray a product called Image or you’ll look for another company.

Also, maybe Ted or Phil could tell you if putting down a pre-emergent would help this late in the year or if it would be wasting money.


[This message has been edited by Alex_in_FL (edited 19 June 2004).]

ted – posted 19 June 2004 13:26

good advice. yeah, it’s too late for effective crabgrass control. all pre-ems “break down” when temps hit the 90’s. best time for pre-em in your market would be early of next year, but since florida is such a different animal from the rest of the country, i would refer to our editor for more exact advice.

SAGBELS – posted 19 June 2004 18:38

Thanks for the help, guys. I am so glad to have found this site.

ps – posted 07 July 2004 16:28

I have heard that pre-emergent Dimension can be applied to new St. Augustine sod (10 days after laying) to prevent crabgrass.

Does anyone know if I can pull crabgrass and have it work?

Eeya – posted 12 July 2004 20:15

I, too, have been bothered with crabgrass and still am. From what I have been told, if you try to pull it out be sure not to shake the dirt back in the ground as it drops the seeds back in the dirt and will germinate later on. Also, I was told that pulling it out is more work but helps to rid yard of crabgrass. Good Luck.

stoutmd – posted 24 July 2004 20:19


I sodded a lawn here in Jackson, MS back in October with centipede and now I’m fighting crabgrass as well as another grass/weed that looks a lot like bermuda. Could this be torpedo grass? It comes from a clump and sends out stolons in all directions. It looks similar to centipede runners, but the blades are much finer (like bermuda. It seems to be able to choke out the centipede. Does anybody have a pic or torpedo grass for me to see? I’ll try to take a pic of what I have tomorrow. How does one post a pic in a message here?

Thanks,JIm Stoutstoutmd@yahoo.com

RMahanJr – posted 27 July 2004 13:30

Does Image really work as well as Asulox?

seed – posted 27 July 2004 19:49


Regarding torpedograss, it is definitely not clumping. Here are two not great photos:

Richard in Tampa – posted 01 August 2004 09:34


I recently had a my neighbor’s lawncare company come an look at my yard. He said to scrape it and resod because of the crabgrass. I mentioned Halts, Atrazine, and Image. He said they were effective pre-emergent controls, but wouldn’t work above 90 degrees (someone else on this posting said that also) or on existing crabgrass. Since my crabgrass is constantly seeding and it’s above 90 degrees for much of the year, I am in trouble. Azula (or something like that), which is approved for agricultural use. but nothing is approved for either the homeowner or the commercial service that works on residential lawns. He mentioned a solution, which I could use, but he couldn’t because the product wasn’t made for crabgrass control. He said 3 scoops of Arm and Hammer detergent (the non-bleach kind), in a gallon of water, would kill crabgrass and leave the St. Augustine. Before I try this, does anyone have any experience with it? The lawn care guy said it could be done any time of the year, although it would work faster in the hot weather.

ted – posted 01 August 2004 13:26

this poor guy has the kind of multiple sources of bad info that really make this business tough. only Halts in your list is a pre-em, and it’s not a very good one ( off the shelf) and i’m not sure it’s labeled for warm weather grasses. your lawn care guy ( if he’s licensed!!!) will be able to obtain the proper products for the crabgrass control, ( provided it’s crabgrass) – post a pic. there’s no need to rip up the yard if it’s crabgrass- crabgrass is an annual weed, meaning it lives and dies all in the same year. wow…

Alex_in_FL – posted 02 August 2004 20:25

Never heard of this solution – but heck, give it a try and post the results.

Image will kill the crabgrass. The heat is an issue however.

There was a poster out of TX that loved St. Augustine grass. His handle was DCHALL_TX or similar. He swore by baking soda. I think you sprayed water on the crabgrass and then sprinkled it with baking soda. Never tried it personally. However, I will in a few weeks. The house I am buying has a full crop of crabgrass. Lots of opportunities to try lots of different alternatives.


unregistered – posted 09 August 2004 13:21

living in the Orlando area for 5 years I have tried them all. Baking soda actually works but it seems to stunt the St. Aug. grass a little and it takes a while before the spot fills in. The best way to keep the crabgrass in control is to hit your lawn early in the year with a pre-emerge herbicide and then keep a close watch as the year progresses. When you see a spot put on the work gloves and start pulling.

bluesea112 – posted 23 August 2004 08:40

Image is expensive but worth it! I live in Dallas, TX. I sprayed my entire Raleigh St. Augustine yard with Image 4 weeks ago and the crabgrass finally started turning brown and dying 4 days ago. Image takes a while to work, but it DOES work. Image is not an instant killer of crabgrass. It is absorbed by the root and kills the weed over 3-4 weeks time period. I mixed 2 ounces of Image per gallon of water into a pressure sprayer. I walked slowly across my yard in a checkered board pattern. The amount of spray is hard to judge, but if it helps, I sprayed until the blades of grass started to drip. Spray only in early morning or late evening, when temperatures are cooler or you could damage your St. Augustine. The best time to spray is when it has not rained for a while. After spraying, run your sprinkler for 5 minutes so that the weeds drinks up the Image.If I was you, I would fire the lawn guy who told you Image was a pre-emergent. Good luck.

unregistered – posted 29 October 2004 14:36

As a Licensed L&o professional who works with hundreds of upper end clients, please be weary of those who support the use of Image. It heavily stunts the growth and color of St, Augustine grasses and is much too expensive for the results you receive. It will only stunt or kill some of the crabgrass, usually only in well shaded spots. There are other products my company uses which are legal that are much more effective and less costly. They are hard to find and if you’re that deturmined to get rid of that crabgrass and willing to do hard research, I’m confident you will find these mixtures eventually. We do not give it out due to the fact that we crush all our competition with these chemicals. Good Luck and learn your chemistry. By the way most of the big companies are totally baffled by what we do and can’t seem to figure it out. Research, expirimentation and time is all that stops anyone from finding the answer, and by the way it’s not expensive to attain and mix these chemicals and customers pay a fortune regularly for us to apply them.

Alex_in_FL – posted 22 November 2004 17:55

Pardon me but this is one of my pet peeves. These “secret recipe” stories. Especially those that “crush” the competitors.

Weed control with chemicals is not rocket science. It takes a little research and common sense (experience usually helps but doing something wrong and getting a good result once can lead to bad habits).

If the previous poster is using products for crabgrass that are not labeled for crabgrass then they are mis-using the products. And can (and should) have their applicator license revoked (in my humble opinion).

In this case, control the crabgrass with a proper dose of image then use a pre-emergent in the spring (maybe put out two doses of pre-emergent – cheaper than fighting to de-weed later). Crabgrass is easy if you just tackle it smartly.

Good luck.


Richard in Tampa – posted 28 February 2005 06:12


It’s now spring here in Tampa. Most of the crabgrass is dead, thanks to the cold weather. I put down Halts about January 1, and again on February 26. Crabgrass is now beginning to grow (I think Halts is really a crabgrass feeder). My Arm and Hammer approach seems to stunt, but not kill, the crabgrass. This has given the St. Augustine a chance to grow a bit, without the competition. Any suggestions. I’m confused as to if I should continue my Arm and Hammer approach, put down Image, put down Atrizene, or buy some “Secret Formula”. I had Chemlawn come again, and they suggested the bulldozer approach (once again). I also put down Bonus S, to stop the other weeds, and give the St. Augustine a nice feeding.

Any suggestions or help would be appreciated.


Richard in Tampa

davidbud – posted 16 May 2005 17:56

NUTSEDGE AND CRABGRASS can be killed by IMAGE! lOOK AT HOME DEPOT to purchase!

gbugh – posted 24 May 2005 12:53

I think vinegar and water 50/50 or maybe 65/35 kills whatever grass you whipe it on so just wipe the crabgrass.

BrianE – posted 30 May 2005 16:55

Richard, I bought a pre emergent product at Lesco called Pendamethalon (or something like that). 1 coat in February and a 2nd 6 weeks later. As of right now I cant find any crabgrass in my lawn! However, I keep a close eye each time I mow the lawn, especially near my neighbors lawn. Pull out what you can, use the Image, but you’ll have to wait until next February to use the pre emergent.

stumpman – posted 12 July 2005 11:17

Where can you find asulox around the Jax,FL area? Thanks!

guest – posted 13 July 2005 09:26

I live in the Fort Myers area with a very large floritam yard in a neigborhood of $700K to 1.5M homes. When I moved into the house, the sprinkler system was broken and the yard was little more than mowed weeds. Two years after undertaking, I have fought all the battles above plus some. Here are a few of my discoveries –

1) image is best on sedge but has limited effect upon the goosegrass, crabgrass, and native bermuda, and hitchhikers.

2) atrazine is a good general purpose weed killer that limits weed growth during winter. It can be purchased at ACE hardware.

3) bleach kills the piss out of bermuda and torpedo grass. If applied in the right proportion it does not kill floritam. Applied with a pump up sprayer, it tips the balance of power and allows floritam to establish control of an area.

4) borax kills the piss out of crabgrass but has slight stunting and yellowing of floritam that last 14-30 days. Applied in the right balance it allows the floritam to overtake and kill the crabgrasses.

5) the best defense is a good offense. My generic mower would cut no higher than 4″ from the factory. I put larger wheels on the mower and raised it to a 6″ cut. The taller the floritam is allowed to grow, the more successful it is at killing off the competition.

6) in areas where the weeds are so thick that floritam can not establish a beach-head, it is best to just spray it down with round-up and re-sod or plug.

7) when plugging, bury the plugs so that the blades just protude above soil. burying too shallow seems to dry-out in the sun and die. When sodding, cut into the dirt so that the sod lies even with surrounding areas. sheets of newspaper seem to make a good weedblock for samll areas and they disintigrate just about the time the plugs are ready to expand their domain.

also, i have done some reading and suspect that baking soda may be just as effective as borax. The primary ingredient of arm&hammer detergent is baking soda.

guest – posted 13 July 2005 09:35

oops – forgot one –

8) use a rake when pulling up crabgrass, carpetgrass, etc. use a motion that pulls the runners up out of the floritam. The floritam is very thick, very strong, and generally stays closer to the ground. By keeping the prongs of your fork parralell to the ground you can comb out the weeds. Most of the weed runners will lead back to a central clump. “Comb” up all the offshoots and pull the central clump. I use a pitchfork underneath the central rootball to loosen the dirt before pulling.

Lucky – posted 13 July 2005 18:35

Can you share how you mix up and apply the bleach and borax? I am so fed up with my lawn care company. My entire yard is overrun with crabgrass. I know that the application timing was wrong for the pre emergent. They said they knew better/had more experience than IFAS. Anyway, my yard is almost 1 acre and pulling the crabgrass is quite a chore. I have best results with a hand tool, a claw, which gets the crabgrass but doesn’t usually get the St. Augustine. However, my knees would LOVE an effective spray treatment. I have tried baking soda and salt solution spray. The baking soda works for me occasionally. Seems the grass needs to be very wet, and the baking soda applied fairly heavy. It damages surrounding grass, but doesn’t kill it. Unfortunately, this just seems to knock back the crabgrass, not kill it. I’ve also found that when you pull up areas of crabgrass, the lawn tends to get dried up in those areas, and then cinch bugs move in. HELP.

guest – posted 14 July 2005 14:37

Put the bleach in a pump sprayer and spray a light misting. It harms floritam too, but it harms bermuda even more. Find the right balance and the bermuda can’t defend itself against the floritam.

But … from your description ….

First, you’ll never kill all the weeds by either pulling or chemical. You need to let your grass do that. If your grass is too thin or weak, then it will lose the war. Cut floritam as tall as possible because floritam can kill almost anything if allowed to grow tall. If you use a cheap mower with a 4″ inch maximum then you’ll never win with floritam. Palmetto is tighter to the ground. If you want to use a $900 riding mower from Home Depot, then maybe you should consider encouraging palmetto.

Think of it as war. Floritam versus weed. Your job is to not to kill the weeds. Your job is to make conditions favorable for the green army to win.

From your description, your green army might be too weak to win anytime soon. Consider strip sodding to swing the balance of power. My yard is about 1/2 acre. It cost me $600 for the sod (laid 1 strip every six feet) and $250 to have someone cut the trenches with a sod-cutter. It’s took about 18 months from weed farm to a lucious carpet of green.

Atrazine and heavy watering during winter were my primary weapons. During the first summer, the floritam spread runners throughout but did not completely cover any new areas. During winter, I stopped mowing and let the floritam grow thick and fill in the gaps. The atrazine held the weeds in check and my heavy watering kept the floritam growing. By early spring only pockets of weeds remained. I broadcast powdered borax by hand into the hotspots and let the floritam finish the job.

Lucky – posted 14 July 2005 18:50

Thanks for the help. I just went out and measured the height of my mower blades from the garage floor, and even at the highest setting on my John Deere, the blades are 3 1/2″. So I will have my husband fix that for me. I have been working on this lawn for two years now, and my front yard is in great shape. The back yard (north side of the house) is still struggling. We had much of it resodded last year because the spray company messed up and let cinch bugs kill it. Being cheap, they only sodded the very dead areas, so much of the yard is still thin and weak, as you describe. I imagine that is why the crabgrass has moved in so bad. It seemed to happen in the last few weeks, because I’d kept it under control until then. I think the daily rains may have contributed. I will raise the mower blades to about 5″ or more, try your borax treatment in the worst spots, and hope for the best. You do recommend powder borax spreading over a mixing it up as a spray?

Alex_in_FL – posted 15 July 2005 17:29

Your best bets are:

1. Apply Image. It will kill crabgrass. It may stunt the St. Augustine but does not kill it.2. Hand weed (an acre is a lot of work however).3. Try the baking soda (cheaper than borax and borax killing weeds is new to me).4. Mow high and have patience (and put out pre-emerge early next year).

Bleach and vinegar are highly risky. Both will kill everything. You must get both the volume and concentration just right otherwise you either kill everything or nothing. You could just as well use dilute Roundup. Image works but it works via roots and thus takes 2-3 weeks.

Also, Image is labeled as crabgrass killer and bleach is not. Atrazine does not kill crabgrass.

Recommendation: Buy Image and expect results in 2-3 weeks.


[This message has been edited by Alex_in_FL (edited 15 July 2005).]

Lucky – posted 15 July 2005 18:30

Thank you Alex. Actually, my lawn care company can put out the Image for me, so I’ll give that a shot. I paid for a year up front, and am supposed to have unlimited treatments as needed. The argument comes in because they don’t want to treat when I think it’s needed! They say that nothing works on crabgrass, and recommend Roundup and resodding. I will insist that they apply the Image. I have a spot with sedge too, so they can treat it all at once. In the meantime, I’m pulling up what I can, and running some test spots with baking soda, borax, salt water.

Alex_in_FL – posted 16 July 2005 22:48


Three points:

1. Image is not “roundup” for crabgrass but it is labeled for control. Thus you will not erraticate (sp?) it but you will severely set it back/kill it.

2. Ask your lawn care “professionals” why Image is labeled for crabgrass control if it doesn’t work. Seems the manufacturer would have been sued for fraud by now if that were the case. Image is about 5X more expensive than atrazine (which is what they use and it has minimal impact upon crabgrass).

3. Another option is to get a two or three foot long piece of 4″-6″ diameter PVC pipe. Place the pipe over the crabgrass then insert a spary nozzle and spray inside the pipe with roundup (or pickling vinegar but round up works great!!!). This spot kills the crabgrass. This can also be used on other weeds like sedge.

Good luck!


Lucky – posted 17 July 2005 18:00

quote:Originally posted by Alex_in_FL: your lawn care “professionals” [/B]

EXACTLY! That’s why when my year is up, I will be looking for another company. Is this website able to give recommendations?

David – posted 23 July 2005 10:59

I live in Central Florida with a Floratam and Bitter Blue (shaded areas) lawn. I too have used the Lesco with PEM every year in Feb, but I still had some crab grass. This year I bought Andersons 25-x-y with PEM from Sunniland. It smells much stronger – like moth balls – than the Lesco product. I applied it in mid Feb and May at 1.5 lbs per 1000 ft*2. Until July I have had no crab grass at all and even now only small patches.

I hope this helps.

Interestingly I never get crabgrass in the Bitter Blue areas?

Does anyone know what states allow Asulox (asulam) for non-agri/residential use?

beachfever – posted 27 June 2010 16:29

In SC the sod farms use post to rid st augustine of most grasses. Including bahia, bermuda and cradgrass. The generic name I use is vantage.Active ingredient Sethoxydim. A product of Southern Ag. PO Box 218 Palmetto, Fl. I’m in SC I don’t work for the company it does work. I purchased from a local feed and seed store. This product does not work on broadleaf pest.

turfgrass – posted 01 July 2010 07:53

Sethoxydim on St. Augustine is a no-no.

The best product for getting crabgrass and a wide range of broadleaves out of St. Augustine in residential sites is Bayer’s “Celsius”.

itsme – posted 13 July 2010 15:11

We have so many kinds of “crap” grass it’s not even funny. It’s sad because we had a beautiful St Augustine yard before a lawn care company killed it. They paid for sod to replace it but we did the work. That lasted less than a year. Then, they killed it again. This time, they paid a company to rip our lawn out and install more. I had my hopes of my beautiful yard back. BUT, they bought the sod from Aduda sod and it is FULL of every kind of carpet and crab grass imaginable, and hardly any St Augustine. I am LIVID to say the least. And the lawn service company wants to come out and treat the lawn, but they say they can’t kill crabgrasses. I think it’s starting to get a fungus in one area b/c of all the rain. I’ve been pulling to no avail. It’s gone amuck. Some of it grows much taller than the St Augustine, and some of it spreads like wild fire from a central base. No bermuda. I guess that’s a plus…haha There is SOME St Augustine, but it is precious and thin compared to the garbage grass. Does anyone have any suggestions? John Deere said Celcius would kill most of it. It’s mid July, hot & rainy here in central Fl. Any help would be greatly appreciated by this exasperated home owner.

hydrocynus – posted 21 November 2011 14:37

I found VERY conflicting info in this thread. Some products mentioned (e.g. Image to kill crabgrass, sethoxydim etc.) actually are labeled to not being used on Floratam.

After a chinchbug infestation (and my reluctancy to use Arena or merit to kill them), my lawn got left with a weakened turf prone to weed infestation. I did not use a pre-emergence weed control and now my lawn in covered with weeds and especially crabgrass.

Without Asulam, I do not seem to find a product that will kill the post emergent crab grass.

I have used baking soda on wet turf sprayed with water and a few drops of detergent and that killed most of the weeds and damaged crabgrass (but left the roots intact). My lawn is ~4000 SF, so that is about 60 pounds of baking soda applied.

Crabgrass seems to recover and I am reluctant to do another treatment because of salts buildup in the soil (sodium).

It would be VERY useful to have a list of products that work on Floratam. I have started such a list below. Some question marks remain to be fulfilled.


Control of weeds in floratam lawns:

Atrazine: must not be applied when temp is >90Fbroadleaf control, does not kill crabgrass, but is good as a pre-emergent. Kills sedgesFound in groundwater and drinkable water

Celcius: (Thiencarbazone-methyl 8.7% Iodosulfuron-methyl-sodium 1.9% Dicamba 57.4%), no temperature limitation environmental hazard?Broadleaf control.

Basagran (Sodium salt of bentazon 44%)Broadleaf Weeds, Annual Sedges, and Yellow Nutsedge in established turf. Basagran Herbicide does not kill

turf/grasses. Basagran Herbicide

baking soda: Control of crabgrass and (from my experience, many other weeds). Do not kill the roots.

sethoxydim:will damages St Augustine grass


seed – posted 23 November 2011 23:01

What kills crabgrasses in St. Augustinegrass?

Nothing, basically. Baking soda, maybe, to some degree, with care. Other products that you mention are ineffective or harmful, and not legally applied to St. Augustinegrass, or ineffective, harmful, and illegal.

Sethoxydim (trade names included Poast and Vantage) is harmful to just about all turfgrasses except it has been used on centipedegrass.

gatorengineer – posted 12 June 2012 10:46

Sethoxydim is not labeled for St. Augustine, but I had a bad infestation of Bahia. This stuff DESTROYED and I mean DESTROYED bahia in one very light application. My St. Augustine suffered a little, but it is growing fine after a little damage.

I was smart and used it first in small areas and waited 6 weeks before using it on other areas. I never put over the entire yard, but it removed the bahia cheaply. Image works more slowly and needs two applications to kill bahia but it does work. I also finished my seth. up on the quackgrass which it works moderately well on.

As far as crabgrass, I really don’t have that much problem with it. Everyone seems to get all worked up and it’s by far the easiest to kill. Try using pre emergent throughout the year such as Barricade or Surflan.

A very inexpensive pre emergent that works well is Pendulum 3.3 EC. This will do 35 applications on a 5,000 sq ft lawn or roughly $3.50/5,000 square feet. It does have a yellow color to it, so add blue die to make it green. If you hit your driveway or sidewalk, wash it off immediately.

Check out domyownpestcontrol dot com. They have stellar service, an easy to use website and fast free shipping.

Image does work on crabgrass control as a post emergent. If you say it doesn’t, then you are just flat wrong….period. Image is somewhat pricey compared to herbicides at the above listed website. Instead of $12/5,000 square feet their applications are more like $3/5,000 square feet and it kills most of the same stuff.

As stated earlier, Celsius has great reviews (I’ve never used). Other good ones are Fusilade II and Dismiss. If one doesn’t work, try another one. If none of them work, then that is what we call in the computer field as PEBCAK (Problem Exists Between Chair And Keyboard).

Jeff B – posted 23 September 2012 20:07

I have torpedo grass in a small area. Two years ago I killed the entire area with Roundup and kept it dead for 3 months. Then I tilled the soil down 18 inches and removed all of the torpedo grass rhyzomes. Then I re-sodded with Floratam. Within 6 months, the torpedo grass was back. I read that spraying the leaves with vegetable oil would do the trick so I started trying that. It will definitely kill the grass and supposedly will get the rhyzomes, too. I am controlling it but jury is still out on whether or not I’ll ever get rid of it. It grows in part of our yard that is shady and damp most of the year.

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