What kills st augustine grass?

projectpete19 – posted 03 May 2008 07:11


I live in central florida. About 6 months ago I had a chinch bug problem and had to re-sod my front lawn. I used bitter blue, and up until two weeks ago it was a nice deep green and the blades were thick. I weed and feeded once, two weeks ago some brown spots started to appear, and where the brown spots are the blades of grass are really thin. I did a chinch bug test and none came up. The pics are below, do you guys know how i can fix this?

Brown spot in the middle of healthy grass

close up of thinning grass

Healthy part of lawn

Brown spots

Apple – posted 03 May 2008 08:12

Can you post the name of the products that you used? Has the irrigation been checked recently. The close up pic shows that the leaf blades are now “rolled up” and that is usually a sign of drought or herbicide injury.

projectpete19 – posted 03 May 2008 08:18

i used vigoro weed and feed, but that was a couple months ago. no other herbicides have been used since.

my irrigation system is good i checked that. the only difference is i usually had it going 3 days a week, then for two weeks i tried running it 2 days a week just before this happened. but i put it back to three days a week.

if it is drought damage will it come back now that i have set the irrigation back to three days a week?

Apple – posted 03 May 2008 12:22

Water it in throughly and continue to water 3 days. The appearance should improve in the coming days. If it doesn’t then let me know. If you’ve watched your irrigation run, make sure to set out a irrigation gauge in these areas and be sure it is getting 3/4 of a inch at each watering.

projectpete19 – posted 03 May 2008 12:49

can i just put a cup on the lawn and measure the amount of water in the cup or do I need some type of special device?

thanks for the info

Apple – posted 03 May 2008 13:08

empty tuna cans work or a cup would be fine.I would suggest buying a rain gauge(5$ or so) next time at the store to help know when to water, come afternoon rain season. Last year I had my irrigation issue off for weeks at a time due to mother nature helping out.

projectpete19 – posted 06 May 2008 09:18

I havent fertilized the grass yet since I did the weed and feed a few months ago. Is it safe and will it help to fertilize while the grass is like this or should i wait?

Apple – posted 06 May 2008 14:26

If you’ve been 60 days from last fert then your alright to refert with the proper products.

seed – posted 07 May 2008 19:02

Check again for chinch bugs.


projectpete19 – posted 07 May 2008 19:44


i checked earlier with the coffee can test and I saw one chinch bug. I sprayed sunniland chinch bug killer (with permathrin) are those patches going to come back or are they dead?

i cant believe this is happening again, i just resodded my lawn 6 months ago

Apple – posted 08 May 2008 14:52

Continue to check on the CB’s. Some CB’s have become resistant to certain insecticides so make sure to switch up the active ingredient with each application. Also retreat this area in 7 to 10 days to break the life cycle of any survivors.

Almaroad – posted 12 May 2008 15:54

I just check the “Weed and Feed Label” Just what I expected. 28% Nitrogen–not good at the begining of year especially when just coming out of dormancy, AND THE BIGGIE was the Weed label- 2, 4D. Although slight in number…St. Augustine cannot tolerate it. If the conditions were sunny–even more of a problem. I suggest that you water like crazy to wash it down. There may be more that you’ve done. Why don’t you call a professional to look at the turf and go from there. Too big of a subject to even try to answer here. Roy

projectpete19 – posted 14 May 2008 08:04

i have been water daily and the grass is slowly coming back to normal. thanks for the info, i thought the damage was from chinch bugs.

i did spray for chinch bugs once and am doing it again this week just in case

Almaroad – posted 14 May 2008 18:27

What are you using to spray? Just for your own peace of mind: Go to a Lesco and talk with one of those guys. Generally those non-specific things like Bug-B-Gone, Clinch Away, etc, do more harm to St. Augustine than good because most of those companys are based in the North and they’ve never dealt with warm-seasoned grasses–There’s a world of difference between Kentucky Bluegrass, Kentucky 31 fescue and Bitter-Blue or Palmetto St. Augustine. Just like some manufacturers list St. Augustine as being tolerent of 2 4-D. Yea, it is in minute quanities, but minute quanities do not take care of the problem. Do yourself a favor and buy that expensisve stuff and never look back. I just paid $260 for a lb of pre-em and $230 for a pint of liquid to treat Green Kyliinga. Expensive but it all works because it is specific….a lot cheaper than resodding a yard.

How to Treat and Prevent Brown Patches in Your St. Augustine Grass

So you finally thought you had your lawn in tip top shape and all of a sudden your St. Augustine Grass gets covered in large brown patches, and this time it wasn’t your neighbors dog. Large brown patches now cover your lawn and you just don’t know what to do.

But Here’s the thing, you are not alone your lawn can be revived!

St. Augustine grass, is a popular thick growing warm season grass, that easily keeps most weeds at bay. Unfortunately it is susceptible to brown patches which most commonly occur in early spring and late fall. But what do you do to get your green lawn back, and how can this be prevented from happening again?

What causes brown patches in St. Augustine Grass?

St. Augustine Grass is susceptible to a type of fungus aptly called brown patch fungus. Brown patch fungus unsurprisingly causes large brown patched in the lawn. Brown patch fungus proliferates in cool wet conditions.

Maintaining your yard properly can prevent this type of fungus from destroying your lawn. Most steps for patch fungus prevention are typical for maintaining any yard, but St. Augustine grass can be a bit more sensitive.

For more on taking care of any lawn check out out The Ultimate Lawn Care Guide

6 Steps to prevent brown patch fungus in your St. Augustine grass:

Step 1: What time is it? Time to get a watch or at least a water timer. Don’t Water at the wrong time!

Watering the lawn too late in the day will leave the lawn damp at night. This is especially problematic in the cooler months as this is precisely the conditions brown patch mold thrives in.

Instead water in the early morning, preferably at sunrise. This will give the grass blades time to dry before nightfall.

Step 2: It’s true your grass needs water, but not too much! Don’t drown your lawn.

Watering too frequently causes the damp conditions that brown patch mold loves. St. Augustine grass should only be watered once it is dry and showing signs of drought, typically every 5- 10 days. St. Augustine grass is semi-drought tolerant, and does best when watering is done only as needed

The recommended depth to water St. Augustine grass is 4- 6 inches. This is not 4-6 inches of water, but instead the depth into ground which the water is reaching. Based on your lawns drainage, the amount of water needed could vary.

Step 3: Avoid Using Nitrogen rich fertilizer in early spring and late Fall. The only thing in common with brown patch mold and you, is you both like fresh green grass.

Nitrogen fertilizer promotes lush green growth, and this soft growth is just what brown patch fungus enjoys. This new growth provides a nice platform for the fungus to grow on. Fertilizing too early or late can lead to fungus growth. Instead use nitrogen fertilizer only in late spring or in the summer.

Step 4: Ensure good drainage and treat compacted soil.

Compacted soil provides poor drainage, again leading to a lawn with too much surface moisture. Avoid this problem by aerating your lawn at least once a year, and maintaining a good PH in your law.

Step 5: Control your Clippings!

To avoid spreading the brown fungus control your grass clippings by mowing your yard regularly. Mowing your yard every ten days to a height of 2.5 – 3 inches is optimal for St. Augustine grass. Timely maintenance will avoid too many clippings from building up. If you want to cut the grass shorter, you will need to cut it more frequently.

You want to keep clippings from clumping up and creating too much thatch, thatch can also lead to excess moisture.

Step 6: Want Faster Results Using Fungicide Early May be your Key

Using fungicide early can be an effective way to control brown patch mold. There are many fungicides to chose from, and the one you chose will be largely dependent on what is available in your area, as well as the type of application that works best for you. Whichever fungicide you decide on, follow the instructions on the packaging. Most fungicides will need to be applied once or twice a month. For the best results, be certain to begin use fungicide at the first signs of brown patch fungus.

As you can see, the main concept of all of the steps to preventing brown patch fungus is to avoid excess moisture in your lawn.

If you have brown patches in your yard that are not caused by brown patch fungus, perhaps you should check out “What is Causing these Brown Patches in My Yard?”

For further reading here is a very through guide for maintaining St. Augustine Grass, by the Texas Agricultural Extension Service HERE

mark_shiffer – posted 05 March 2001 12:10

Does anyone have any good ideas on how to get rid of my St. Augustine grass?

I live in Austin, TX where we get a fair amount of rain usually, but I let the drought last year kill off as much of the lawn as it could because I cannot stand the horizontal growth of St. Augustine grass.

I have read some and thought zoysia might be a good choice, but can I overseed the St. Augustine with this, or do I need to till the lawn and prepare a decent seed bed for it? Will it even grow well in Central Texas? It seems everyone around here has Bermuda or St. Augustine…

Any help would be greatly appreciated.

seed – posted 07 March 2001 10:49

Mark, it’s fairly easy to kill St. Augustinegrass with Roundup herbicide. Just follow the label, and make sure that the St. Augustine you want to kill is in a green luxuriant state of growth.

Your other questions do not have such easy answers. Zoysiagrass is a promising grass in many of the transitional areas between the cool-season grasses such as tall fescue and the warm-season grasses such as bermuda and St. Augustine. But promises and realities are two different things. For one thing, zoysiagrass seed is not commonly available commercially, and even if it were, you would need to prepare a good seedbed. Whatever you plant, you do not necessary need to till the ground unless it is compacted, but you do need to remove the debris to get good contact with the soil, and sometimes tillage is an unavoidable necessity just to get the surface layer of soil worked up.


mark_shiffer – posted 07 March 2001 12:23

Last year during the drought, I refused to water my lawn for two reasons: 1. The Drought and 2. I hate St. Augustine grass (The sideways growing, hard grass), and figured why not kill it off then plant new grass.

I should have thought ahead in the process, but here I am dealing with the aftermath. I have a 90% dead lawn. Most of what is alive are weeds. My idea was to start anew.

From what your saying though I should probably Round-up the whole lawn to kill all weeds and what is left of the grass. Then till the remnants under and plant, right?

I have found zoysiagrass seed available on the internet. Anyone know about the viability of zoysiagrass in Central Texas weather?

seed – posted 08 March 2001 12:14

Mark, please post here a web address for the zoysia seed, so we can all check it out.

Yes, when you intend to kill your St. Augustine, it’s best to start with the most powerful tool first, and that is Roundup. It’s not too late to use it to clean up the aftermath, but I remain concerned about the possible escape of underground rhizomes of weeds.

PLAN for the uses, environment, and maintenanceERADICATE noxious weeds with Roundup, etc.GRADE the rough contour, including remove debrisIRRIGATE, install or renovate the irrigation systemSEEDBED, do a final smoothing if the soilINSTALL, plant whatever turgrass you needDEFEND, against drought and weeds


Rose – posted 12 April 2001 17:57

rubby – posted 21 January 2003 01:21

I live in Sacramento and I tried Roundup, purex, water softener salt, boiling hot water, and digging my entire front lawn up! Nothing has killed the st augustinegrass! The nursery people don’t know what will kill it either. I have spent 5-years trying to kill this grass. It is coming through and under the fences. It is brown now, so I star again every winter alternating salt(which slows the growth down) then vegetation killer. It still creeps over the salt and returns. Easy! Puppy Cock!

Will-PCB – posted 21 January 2003 22:49

Well hell. I kill my St. Augustine grass routinely (by accident of course). Its the damn weeds I have trouble killing.

Interesting that I was plush St. Augustine and hurt it constantly (requiring replugging areas frequently), yet you want to irradicate yours, and cant.

Murphy’s Law rules in Lawn Maintence.

forrest – posted 02 March 2003 23:31

well shucks, her i was, all set on finding(somewhere-this is california and no one seems to transport st. augustine) this stuffand now I’m thinking to take a second look.I have pet pigs and chickens, though; they really do a number on conventional grass, even bermuda grass seems to be losing thebattle. Anyone has suggestions?

ted – posted 04 March 2003 21:50

i can’t believe some of the advice on this board…

first of all, why do you want to get rid of the st. aug? it’s a perfectly functional grass for the area! people generally don’t like it because they’re too lazy to weedeat, since the grass sends runners out into the flower bed. both bermuda and st. aug. will work in austin, but if you’re itching to use zoysia don’t use seed!!!! you’ll have to wait until the st. aug. is back and strong again ( and it will be) then around say may or can use 46% professional strength roundup ( buy it at lowes) and spray the lawn at 2.5 ounces per gallon on your backpack sprayer. you may have to do it twice. then after it’s dead, yank up all of the sod, and resod with zoysia, make sure you’ve smoothed out the soil first, then lay the new , fresh sod. there’s alot of stuff online about zoysia, probably texas a and m has alot of info or you could call their extension office. better yet, why not call a local reputable landscape company???? you might try calling your local lesco service center , as well. sorry for the gripy comments, but there’s so many people going around beating their heads against the wall, and so much crappy advice, it’s unbelievable..

a chemical lawn care company owner in houston

[email protected] – posted 21 June 2003 09:55

i want to kill zoy grass badly…do not want to sterilize the soild….how about an inch of newspaper under several inches of bark and allow to turn into mulch???????please advise rush…penna is very wet this year….zoy grass is now green and looks nice, but it is yellow and looks dead most of th time….7-8 mos per year…good weed killer…but, it keeps spreaduing./…..we hate it

help…bob greene [email protected]

crid – posted 27 June 2003 21:34

The organics are coming. They are superior. They are easy. And most of all, it’s the right thing to do. Check it out.

Dchall_San_Antonio – posted 27 June 2003 23:30

I’m just south of you in San Antonio. I remember when I came from the land of vertical growth grasses (Dayton, Ohio), I had a little trouble getting used to St Augustine, too. Now I love it. The way I’ve heard most people killing their St Aug (accidentally) is by smothering it with compost. So you might try mulching it with at least an inch of anything you have handy.

AJ – posted 30 July 2003 13:30

Mark, I live just outside Austin. When I build my house the builder gave me a choice of St. Augustine or Tif Bermuda. I chose Tiff Bermuda because I have rather large lot wanted less maintenance. I love this grass. It is a slow grower, doesn’t need to be mowed as often, it is softer and darker green than St. Augustine. Some neighbors cut it short like a putting green. The most amazing feature is that it isn’t as invasive as coastal bermuda. I have plastic edging around my flower beds and it rarely crosses it. I have seen adds for El Toro Zoysia for Austin, I looked into zoysia but it is very expensive. For info on turf grasses check out the TAMU web site for Aggie Horticulture.aggie-horticulture.tamu.edu/tamuhort.html

My problem if someone can help is that my neighbor has St. Augustine and it is invading my Tif Bermuda! How can I kill the St. Augustine without killing my bermuda?

Dchall_San_Antonio – posted 31 July 2003 08:42

AJThe only way you’re going to be happy is to put in a 4 inch wide and 4 inch deep border between your two lawns. If you do it soon, you can pull out all the St Augustine. Or you could put in a ground cover between the two. You might ask your neighbor if he’d be willing to go halfseys on either of the two. He might be willing to share a common ground cover like Asiatic jasmine. You’ll both need a steel border to contain the jasmine because it can be invasive, too. But with a border, it works great.

I have both jasmine and a 6 inch wall between me and my neighbor. Trimming is pretty easy.

BermudaDallas – posted 09 August 2003 18:00

MSMA Crabgrass killer will kill St. Aug. w/o hurting Bermuda-good luck!

VooMan – posted 10 August 2003 23:04


I’m with Dchall on this one for sure… I had concrete border curbing installed last year and it was one of the best investments I could have ever made in my yard. I edge the bermuda just like I do along the sidewalks, and it never gets across the border to invade my flowerbeds. It’s four inches wide and deep, and it works wonderfully. 🙂


Lex – posted 24 August 2003 08:18

Just kill the St. Augustine (or zoysia) with Roundup. The active ingredient is rapidly broken down in the environment once it hits the soil (I manage a major environmental organization and worked in pollution prevention for years). You’ll do more damage to the environment driving back and forth to buy the chemical than using it.

Why get rid of St Augustine? Lots of good reasons. St. Augustine requires more water (water is an issue in San Antonio and much of TX), it makes the kids itch, could be renamed “chinchbug bait”, and atrazine is about the only reasonably priced weed killer that won’t kill the grass. Atrazine is persistent and is slowly getting into water supplies (some extreme environmental groups are calling upon EPA to ban atrazine or greatly restrict its use). Zoysia and bermuda require less chemcials and less frequent cutting (most varieties).

Dchall_San_Antonio – posted 25 August 2003 10:08

quote:Why get rid of St Augustine? Lots of good reasons. St. Augustine requires more water (water is an issue in San Antonio and much of TX), it makes the kids itch, could be renamed “chinchbug bait”, and atrazine is about the only reasonably priced weed killer that won’t kill the grass. Atrazine is persistent and is slowly getting into water supplies (some extreme environmental groups are calling upon EPA to ban atrazine or greatly restrict its use). Zoysia and bermuda require less chemcials and less frequent cutting (most varieties).

I want to respectfully disagree with a couple (not all) points made above. St Aug does not have to be a water hog. My next door neighbor has not watered her lawn for 4 years which have included some pretty good droughts. It looks pretty darned good all year round. The difference is she trained her grass roots to go deep looking for water. We are not on deep soil, either, so they don’t have to go very deep.

Then skipping down to the bottom, the only reason zoysia doesn’t need to be cut often is it grows so fricken slow. Of course it grows pretty short even when left alone, too. And bermuda should be mowed weekly for the best appearance and softest touch.

I must be more allergic to bermuda because that stuff makes me itch.

Now to go back to the middle of the message above, when properly cared for, St Aug will choke out most weeds. I just got back from Port Aransas, Texas where I saw St Aug invading the dunes, growing unmowed at about 30 inches tall, and as dense as you could imagine. It is taking over all the grasses and forbs in the dunes. So my point here is that you might not need a weed killer in St Aug when you do the right things.

Alex_in_FL (Lex) – posted 08 December 2003 16:46

Please feel free to disagree! I think St Augustine is wonderful… especially in your yard, where you mow it, you edge it, you fight the chinch bugs, and you itch if you play with your kids in it!

As a *general* rule St Augustine requires more water. I am stingy with water to encourage deep roots. So far I have noticed that my floratam usually needs watering before my zoysia even though my zoysia is not yet 2 years old. And I water far less than my neighbors.

My zoysia needs cutting about everyother time I cut the floratam. This suits me! More time to play with my kids, swim in the pool, or even play a round of golf.

Again, feel free to disagree!! I think those of you that prefer mowing grass to playing should fertilize often and water heavily!!!

Happy mowing!!!!!

nohow – posted 03 July 2007 17:09

St. Augustine is the best,install sprinkler system with timer, water for 10 minutes each morning, fertilize twice a year, hire a Gardner! Results = an excellent lawn that neighbors will envy, kids will enjoy and free up every one of your weekends for fun!

How to remove Bermuda from my St. Augustine lawn?

Are you frustrated with Bermuda taking over your lush St. Augustine lawn? Unfortunately, there are only two options to deal with it.

Before I get into solutions, let me explain how Bermuda works. It is very invasive and spreads via seed (when mowed), stolon (above ground “runners”), and rhizomes (underground root system). It is in the grass family, so any herbicide that kills it will also kill St. Augustine grass – which is why it creates such a hassle for Gainesville lawns.

The good news is that Bermuda and St. Augustine grasses can co-exist in Gainesville lawns and the grass can still look overall healthy. We have several clients that have found this to work for them, even if they would prefer to have a Bermuda-free yard. The bad news comes if anything ever causes the St. Augustine grass to struggle, like irrigation issues or insect damage, because then the Bermuda will immediately take the opportunity to really cover that area and will not let St. Augustine back in without being completely removed and having new sod installed.

A good lawn spray technician can utilize pre-emergent* herbicides to slow the spread of Bermuda – but nothing will stop it completely because of the runners.

Some people love Bermuda lawns and grow it as their primary turfgrass, but you rarely see this in Gainesville. Primarily in our area, Bermuda is used for golf courses and football fields. It just takes too much maintenance and fertilizer to keep it looking healthy and lush in our sandy soils to be a good lawn grass.

Here are the two options when it comes to resolving the Wild Bermuda grass issue..

Least Invasive Option – The key for this is to keep the St. Augustine turf healthy enough to keep the Bermuda at bay. You may have to sod any areas that are completely riddled with Bermuda to get a good start.

  • Mow the lawn on your mower’s highest setting. (Bermuda prefers to be mowed low, so this will help the St. Augustine grass)
  • Increased irrigation times to keep the St. Augustine healthy enough to hold it’s space against the invasive Bermuda grass.
  • A good fertilization and pre-emergent weed control program, which we offer.
  • Lawn Insect Control such as chinch bugs and webworms. This is also a service we offer.

Extensive Option – This would involve locating any areas where Bermuda is located, even if it doesn’t look bad yet, to remove and resod so that Bermuda is no longer taking over the property.

  • We would recommend starting with a couple non-selective herbicide applications that will kill the Bermuda grass throughout your yard.
  • Next, you would sod-cut and till the lawn to assure you remove all of the roots.
  • You would apply a soil amendment such as milorganite to help the sod root quickly.
  • Install the healthiest sod available.
  • Lastly, protect the sod with a lawn health program.

Either one of these plans can work if all of the steps are followed, but missing a step assures failure when it comes to Bermuda grass. I encourage homeowners to keep their lawn healthy and a little Bermuda grass will not be an issue. It’s only when the St. Augustine thins out and struggles that it shows up. If we can be of any help in this job, please feel free to call us at (352) 378-5296 or email us at [email protected]

*Pre-Emergents lay a protective barrier down on the soil that won’t allow seeds to germinate, restricting Bermudas ability to spread.

Weed that looks like st augustine grass

grass. Perennial, reproducing by seeds and nut like tubers on roots. foot area. This will kill the weed without damaging the St. Augustine grass! Leaves of three, heart shaped, pale green and bitter to taste due to presense of oxalic acid. This weed is so invasive and troublesome, that just the thought of dealing with it can make you . (Note: St. Augustine grass is a creeping type with long runners. So identification of grasses that LOOK like crabgrass is essential before you start Saint Augustine grass is the best weed control possible.

I have a grass growing in parts of my lawn that looks almost identical to St. Augustine. It spreads by above ground stolons and the leaf blades. It’s a long, stringy weed with runners like St. Augustine. but it looks like one of two things, either nut grass, or as some call it nut sedge or plain. Annual grassy weeds are some of the more frustrating lawn weeds While the seedling look similar to other plants, they soon begin to distinguish themselves. . Note that MSMA and DSMA are not recommended for St. Augustinegrass.

So identification of grasses that LOOK like crabgrass is essential before you start Saint Augustine grass is the best weed control possible. St. Augustine grass (Stenotaphrum secundatum Kuntze) is a Look at the leaves. English daisies (Bellis perennis) have succulent-like leaves. Grass . Crabgrass is a terrible weed to have in our home lawns, it’s a very weedy and fast growing annual grassy Control Annual Bluegrass In St Augustine Lawn.

Centipedegrass vs St. Augustine grass | Walter Reeves: The Georgia Weed ID site Weeds In Lawn, Garden Weeds, Centipede Grass, Identifying Weeds, How to diagnose lawn problems like grubs, dog damage, dry spots, moss, and more. Thread in the Ask a Question forum forum by Pearlgarden This pops up in my yard and it looks just like normal St augustine grass but with. I’m having an issue (among others) with my St Augustine lawn and flowerbed. Weeds are like the last thing on my list for maintenance of.

St. Augustine grass (Stenotaphrum secundatum) is a warm-season lawn grass that is popular for cultivation in tropical and subtropical regions. It is a medium- to high-maintenance grass that forms a thick, carpetlike sod, crowding out most weeds and other grasses. ‘Texas Common’ – Most similar to the natural species , it has fallen out of. grass. Perennial, reproducing by seeds and nut like tubers on roots. foot area. This will kill the weed without damaging the St. Augustine grass! Leaves of three, heart shaped, pale green and bitter to taste due to presense of oxalic acid. This weed is so invasive and troublesome, that just the thought of dealing with it can make you . (Note: St. Augustine grass is a creeping type with long runners.


Dollarweed (Hydrocotyle spp.), also known as pennywort, is a warm-season perennial weed. It gets the common name, dollarweed, from its silver- dollar-shaped leaves. The leaves of dollarweed are round, bright green, fleshy and look like miniature lily pads measuring 1-2” in diameter with a scalloped edge. It has a low-growing habit that spreads by seeds, rhizomes and tubers.

Dollarweed is often confused with dichondra. One way to distinguish the two is by looking at the placement of the leaf stem. Dollarweed has a stem located in the center of the leaf while dichondra’s stem is located at the edge (see image below).

Dollarweed leaf on left and dichondra leaf on right.
Bert McCarty, Clemson University

Before starting a weed control program homeowners should realize that complete eradication of dollarweed (or any weed) from the landscape is not practical. A more practical approach is to control (not eradicate) the weed by limiting the infestation to a tolerable level.

Cultural Control

Dollarweed is a water-loving plant that can float. The presence of dollarweed indicates that there is excessive moisture in the area. Research at the University of Florida demonstrated a reduction in dollarweed just by reducing irrigation frequency (http://grove.ufl.edu/~turf/weeds/dollarweed.html).Monitoring moisture levels and evaluating irrigation frequency are the first steps to controlling dollarweed. Landscape plants and lawns require one-inch of water a week for optimum growth.

A properly maintained landscape that is not stressed by insects, diseases, drought or nutrient imbalance is the best defense against weeds. Proper mowing height of lawns and a 3-inch thick mulch layer around trees and shrubs will prevent the invasion of weeds. For more information on proper landscape maintenance techniques, see the following fact sheets: HGIC 1056, Watering Trees & Shrubs; HGIC 1604, Mulch; HGIC 1201, Fertilizing Lawns; HGIC 1205, Mowing Lawns and HGIC 1207, Watering Lawns.

Chemical Control

Lawns: Dollarweed thrives in weak, thin turf with excessive moisture. The first defense against dollarweed is to reduce moisture levels and modify cultural methods (i.e., proper mowing height and irrigation). After taking steps to modify the lawn care techniques, a chemical control may still be necessary to further reduce the dollarweed population. Herbicides should be chosen according to turf species and applied in late spring (after full spring green-up of the lawn) when weeds are small. Herbicide effectiveness is reduced as weeds mature.

Atrazine can be applied to St. Augustinegrass and centipedegrass up to two times a year. For maximum effect atrazine should be applied once in the fall and again in late spring (after spring green-up). Atrazine has a pre- and post-emergent effect on weeds, which means it helps to control both emerged weeds and weed seed. It should NOT be applied to newly seeded lawns due to the detrimental effect it has on seed germination. Delay atrazine applications to newly sodded and sprigged lawns until it is well-established and actively growing. Examples of products containing atrazine in homeowner sizes are:

  • Hi-Yield Atrazine Weed Killer
  • Southern Ag Atrazine St Augustine Weed Killer
  • Image for St. Augustinegrass & Centipedegrass with Atrazine
  • Spectracide Weed Stop for Lawns for St. Augustine & Centipede Lawns RTS

Dollarweed in a lawn.
Bert McCarty, Clemson University

A three-way herbicide may be used safely on bermudagrass, zoysiagrass, centipedegrass, St. Augustinegrass, and tall fescue. The active ingredients of a three-way herbicide include the following broadleaf weed killers: 2,4- D, dicamba, and mecoprop (MCPP) or MCPA. Examples of three-way herbicides in homeowner sizes are:

  • Ferti-lome Weed-Out Lawn Weed Killer – Contains Trimec®
  • Southern Ag Lawn Weed Killer with Trimec®
  • Bayer Advanced Southern Weed Killer for Lawns Concentrate; or RTS
  • Spectracide Weed Stop Weed Killer for Lawns Concentrate; or RTS
  • Bonide Weed Beater – Lawn Weed Killer Concentrate
  • Ortho Weed B Gon Weed Killer for Lawns Concentrate; or RTS

CAUTION: Herbicides containing 2,4-D should be applied at a reduced rate on St. Augustinegrass and centipedegrass to prevent damage to these lawns. The product label will give the rate to use for each type of turfgrass. If a second application is needed, apply the herbicide in spot treatments. Repeated applications of a three-way herbicide should be spaced according to label directions. Three-way herbicides should not be applied during spring transition (green-up of lawn) or when air temperatures exceed 90 ºF. A newly seeded lawn should be mowed a minimum of three times before applying an herbicide.

Imazaquin (such as in Image Nutsedge Killer) can be applied safely to bermudagrass, St. Augustinegrass, centipedegrass, and zoysiagrass, but do not apply to tall fescue. Apply imazaquin in the late spring (after spring green-up) when weeds are small. A second application can be made in six weeks after the initial application. Do not apply to newly planted, plugged or sodded turfgrass.

Both atrazine and imazaquin can travel through soil and enter ground water, please read the label for all environmental precautions. Users are advised not to apply atrazine or imazaquin to sand or loamy sand soils where the water table (groundwater) is close to the surface and where these soils are very permeable, i.e., well-drained.

The herbicide mix of thiencarbazone, iodosulfuron, and dicamba, as found in Celsius WG Herbicide, is selective to control many broadleaf weeds and several grass weeds in all four of the common warm-season grasses. It cannot be used in fescue lawns, but can be used to remove fescue from warm-season lawns. Apply when dollarweed is actively growing and again 2 to 4 weeks later. The addition of a non-ionic surfactant, such as Southern Ag Surfactant for Herbicides, will increase control (see Table 1).

Once dollarweed has been eliminated in areas of the turf, bare spots will be left behind. To prevent the invasion of new weeds in these bare spots fill them with plugs or sprigs of the desired turfgrass. Fertilize the lawn based on soil report recommendations.

Table 1. Turf Tolerance to Herbicides for Dollarweed Control.

Herbicide Bermuda Centipede St. Augustine Tall Fescue Zoysia
atrazine D S S NR NR
(3- way) 2,4-D + MCPP + dicamba S I I S S
imazaquin S-I S S NR S
thiencarbazone, iodosulfuron, & dicamba1 S S S2 NR S
S=Safe at labeled rates
I= Intermediate safety, use at reduced rates
NR= Not registered for use on and/or damages this turfgrass
D = Fully dormant turf only.
Note: Do not apply postemergence herbicides, except Celsius WG Herbicide, to lawns during the spring green up of turfgrass.
1 This mix of active ingredients requires the addition of 2 teaspoons of a non-ionic surfactant (that is, a wetter-sticker agent to aid in weed control at 0.25% by volume) per gallon of water, such as Hi-Yield Spreader Sticker.
2 Spot treatments to St. Augustinegrass at temperatures above 90 degrees may cause temporary growth regulation.

Landscape Beds: In landscape beds, dollarweed can be hand dug or controlled with an herbicide. Dollarweed is a perennial weed that can emerge from seeds, tubers, and rhizomes. Once dollarweed has made its way into the landscape bed, an herbicide may be necessary if hand pulling is not practical.

Glyphosate can be used for spot treatments around ornamental plants. Glyphosate is a non-selective herbicide that should be used with caution. Spray with a 3% Glyphosate solution in a pump-up sprayer for dollarweed control. Do not allow glyphosate spray mist to contact ornamental foliage or stems as severe injury will occur. A cardboard shield may be used to prevent glyphosate spray from drifting to nearby ornamentals. Examples of products containing glyphosate in homeowner sizes are:

  • Roundup Original Concentrate,
  • Roundup Pro Herbicide,
  • Martin’s Eraser Systemic Weed & Grass Killer,
  • Quick Kill Grass & Weed Killer,
  • Bonide Kleenup Weed & Grass Killer 41% Super Concentrate,
  • Hi-Yield Super Concentrate,
  • Maxide Super Concentrate 41% Weed & Grass Killer,
  • Super Concentrate Killzall Weed & Grass Killer,
  • Tiger Brand Quick Kill Concentrate,
  • Ultra Kill Weed & Grass Killer Concentrate,
  • Gordon’s Groundwork Concentrate 50% Super Weed & Grass Killer,
  • Zep Enforcer Weed Defeat III,
  • Eliminator Weed & Grass Killer Super Concentrate,
  • Monterey Remuda Full Strength 41% Glyphosate,
  • Knock Out Weed & Grass Killer Super Concentrate,
  • Southern States Grass & Weed Killer Concentrate II,
  • Total Kill Pro Weed & Grass Killer Herbicide,
  • Ace Concentrate Weed & Grass Killer.

Imazaquin (Image Nutsedge Killer) is a selective herbicide that can be applied safely around certain landscape plants; see product label for a listing of the plant materials. Imazaquin should not be applied around the root zones of plants not on the product label. It is best to apply imazaquin when weeds are small in spring. A second application can be applied six weeks later if necessary.

Glyphosate and imazaquin are both more effective when weeds are actively growing and should not be applied under drought conditions. As with all pesticides, read and follow all label instructions and precautions.

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