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How To Get Rid of Torpedo Grass In Your Lawn

by Aaron Alfson 25 Aug 2020

One of my biggest enemies is Torpedo Grass. The Univeristy of Florida calls it “one of the most serious weeds in Florida.”

It spreads via long rhizomes that can creep for several hundred feet under streets, driveways and even your house. It can also re-grow from even the smallest clipping which means pieces of it get caught in lawn equipment or spread by birds that like using it for building nests. It tends to love wet areas, so you will notice it spreading during the rainy season the worst, and tailing back during the dry season; but it’s always there, waiting to compete with your lawn.

Get Rid of Torpedo Grass In Zoysia and Bermuda Grass

I’ll address this one first since it was a topic of my video this week. That video points out one of the key ways to keep torpedograss out of your lawn, and that is having a thick lawn in the first place. In the video, you can see that the areas where I opened up the ground, the torpedo found its way in.

The University of Florida backs this up by saying “Weeds such as torpedograss generally invade open or disturbed areas – following a burn, clearing mowing, etc., so these areas are particularly vulnerable to invasion.”

The good news for those of us with Zoysia or Bermuda lawns, is there is a selective herbicide available that can knock it back pretty good. “Selective” herbicides are those that will harm the targeted weed or in this case weedy grass, but not harm the lawn. For zoysia, that herbicide is quinclorac 75 DF. (DF stands for “dry flowable” as this is a dry product you mix in water to make a liquid spray)

You’ll know this one because it’s the same herbicide that I recommend for fighting crabgrass.
Keep in mind though, because torpedograss has those very long rhizomes that creep for long distances below ground, you may see it dying up top but the rhizome below will still be there to push new growth back. So the key is to spray the torpedograss with the Quinclorac but at the same time, continue pushing the zoysia with fertilizer so it can fill in and help you choke back the torpedo invasion. Zoysia likes to be pushed so you could use 24-0-4 CX DIY Turf & Ornamental Fertilizer
to keep it moving and spreading and taking ground while the weed control stunts the torpedo grass.

Do not mow the lawn for 2 days prior to spraying and for at least 2 days after but giving it 5-6 days after is even better. Quinclorac translocates down the plant so cutting too soon is kind of like cutting off your hand when you get bit by a snake to stop the poison from getting to your heart. Graphic analogy but it illustrates the point well - let that chem move through the plant.

It’s also important that there is good soil moisture present before the app. Watering a good ½” the day before your application is a good idea if you are not getting rain. This is because soil moisture means the torpedo grass is actively growing. If it’s dry in the soil, it closes itself off and this slows or even stops the quinclorac from getting through.

Note: it is suggested that you use an adjuvant with this product. This will give you better control and the best adjuvant to use is methylated seed oil. This is not required but can increase the efficacy of your applications. I have used general purpose surfactants with it and gotten excellent results.

Note2: Some hybrid bermuda cultivars may turn a little yellow after an application of quinclorac but this will not last long. I still recommend that you spot spray to minimize this damage.

Get Rid of Torpedograss in St Augustinegrass and Centipede

I face this one too.I have Floratam and Palmetto St Augustine grasses in my front and side lawns. Sadly, there is no selective herbicide available that will control the torpedograss if you also have this grass type, but I do have some decently good news.

First off, torpedo grass actually blends in ok with St Augustinegrass. It’s not ideal, but it doesn’t stick out like a sore thumb like it does in zoysia or bermuda. The wider blade of torpedo grass resembles St Augustine and Centipede fairly well. Torpedo grass also turns pretty dark green when you hit it with iron, just like your St Augustine will and to a lesser degree, centipede grass too.

If areas of the lawn get too thick with torpedo grass and you just can’t stand it anymore, this is where surgery comes in. Many of us here in Florida are accustomed to waiting until areas get really bad, then we just cut out a nice big square and resod it. A pallet of sod will cover 400 sq ft and costs around $250. This is an option we often have to choose with St Augustine and Centipede not only for invading torpedo grass, but also for the invading common bermuda that also has no selective herbicide available for its control.

Good News - Torpedograss and Scotts ProVista St Augustinegrass

There is a newer variety of St Augustinegrass available that has been bred to be glyphosate tolerant. Glyphosate is a non-selective herbicide which was made famous as the active ingredient “RoundUp” weed and grass killer. Nowadays, you don’t have to buy that brand, you can get straight 41% glyphosate concentrate and mix up your own. Glyphosate kills pretty much everything, including torpedo grass, but it will not kill Scotts ProVista St Augustine Grass because as I mentioned, that grass has been genetically modified to tolerate glyphosate.

Here is a full video where I talk about it and the benefits you can get from it.

The price of ProVista has come down now and it’s not much more expensive than other varieties of St Augustinegrass, however, with this strategy, it does require you to re sod your entire property, so there’s that. It’s not easy to just come in, cut out all your existing sod, and resod - but for some of you who are at your wit’s end with torpedograss and other invaders like signalgrass or wild bermuda, this is an option that you only have to do one time and you’re good. Big investment I know, but it at least it gives you an option.

Get Rid of Torpedo Grass in Bahia
I saved you guys for last because sadly, I don’t have an option for you either. I really need to show some more love to my bahia grass friends - most of you are along the Gulf Coast which is where I live, but the truth is, your options for pretty much every herbicide are very limited.

There you go, all the options I have for you with the dreaded scourge torpedo grass. If you are fighting it and winning, feel free to tweet me a picture of it suffering and declining in your lawn! I love to see weeds in pain.

 

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