Torpedograss is a notoriously difficult weed to control. The most effective way to get rid of torpedograss is post-emergent herbicides like quinclorac or glyphosate. Other options include digging it out and a full lawn renovation.
Torpedograss at a glance
Brought into the U.S. over a century ago, torpedograss is found mostly in the Gulf States. Called the “creeping panic”, this warm-season perennial grass is so prolific that it is considered a noxious weed in Alabama, Arizona, Hawaii, and Texas. It invades lawns, landscapes, gardens, and even bodies of water.
Torpedograss gets its name from the hard and sharp white-colored tips on its rhizomes (underground stems). Likened to torpedoes, these rhizome tips can pierce through weed barriers that prevent other weeds from spreading. It spreads mainly through rhizomes, and they’re by far the most reliable way of identifying torpedograss.
This grassy weed has waxy leaves that are either flat or folded, around 10 inches long and 0.1 to 0.2 inches wide. When allowed to grow long, it grows to about 3 feet tall. Found only in warm-season turf, it can blend in with desirable grasses – mostly Zoysiagrass and St. Augustinegrass – and even native grasses in the wild such as maidencane.
How to remove torpedograss
There aren’t many options to effectively remove torpedograss, especially if you want to save money. Let’s go over the options to get rid of torpedograss:
- Post-emergent herbicide
- Lawn renovation
Will hand-pulling work? Hand-pulling torpedograss is only effective on young plants in landscape beds, not on lawns. Since it mainly spreads through rhizomes, you’ll need to make sure all of the plant gets removed; otherwise, it will regrow. That’s a problem when it has rhizomes that can reach up to 20 feet long; you’d be better off spraying or renovating your lawn.
Post-emergent herbicide
Applying post-emergent herbicides is the lower-cost option to control torpedograss. You can use either selective post-emergents or non-selective post-emergent weed killers. When applying herbicides on torpedograss, spray in the summer when it’s actively growing.
Selective post-emergent weed killers will leave desirable plants untouched, making them the less destructive option. Here are the two post-emergent herbicides you can use on your warm-season lawns:
- Quinclorac. This kills torpedograss over multiple applications and also targets other grassy weeds. However, it can only be used on Bermudagrass and Zoysiagrass lawns.
- Sethoxydim. This post-emergent is less effective but can be used to control torpedograss on centipedegrass and Bahiagrass. Notice how we say control; unfortunately, sethoxydim won’t kill torpedograss. It will only prevent it from spreading more, and this weed will come back when you stop spraying it.
Apply sethoxydim at least three times in the summer.
Note: There are no selective herbicides safe for St. Augustinegrass lawns that will work on torpedograss.
You can use fluazifop if you’re trying to target torpedograss in landscape and garden beds. Just make sure to check the label if any of your ornamentals will be harmed by it.
Non-selective herbicides will kill all plants. If you want to prevent as much damage as possible, try to limit the spray to torpedograss. Unfortunately, that’s not always an option, especially on lawns. You want to use a non-selective that’s also a systemic herbicide so it can kill the torpedograss rhizomes underground.
One non-selective you can use to kill torpedograss is glyphosate. You may need to spray glyphosate twice to successfully get rid of this grassy weed.
Lawn renovation
This is the more drastic option – very costly, but very effective. You will need to kill off your whole lawn to target all of the torpedograss and then start all over again. You can remove your grass and weeds through the following methods:
- Non-selective herbicides
- Manual removal (sod cutter or other digging tool)
- Solarization
- Sheet mulching
Note: If you use a non-selective herbicide, make sure to use one that doesn’t prevent seed germination.
Next, you’ll need to fill your lawn in again. You can grow grass from seed or install sod.
Regardless of what option you go for, you may want to change what type of grass you put on your lawn again. Dan Gill, a horticulturist with the Louisiana State University AgCenter, suggests installing Bermuda or Zoysia so you can use quinclorac against any invading torpedograss in the future, negating the need to go for complete lawn replacement.
FAQs about torpedograss
How do I prevent torpedograss?
Here are some ways to prevent torpedograss:
- Don’t bring mowers from infested areas as that can introduce torpedograss into your lawn.
- Use high-quality landscape filler, mulch, and soil as they’re less likely to have weed seeds and cuttings.
- Fix bare patches that will otherwise be taken over by torpedograss.
- Fertilize for a strong lawn that can fight against torpedograss and other weeds.
Unfortunately, most traditional weed prevention methods won’t work against torpedograss.
Do pre-emergent herbicides prevent torpedograss?
Pre-emergent herbicides won’t prevent torpedograss because it’s a perennial grassy weed that spreads through rhizomes, which this type of weed killer can’t fight.
Also, torpedograss doesn’t produce viable seeds. In other words, the seeds often don’t germinate and survive into healthy adult plants. These unviable seeds are another reason why pre-emergent herbicides won’t prevent torpedograss.
How is torpedograss getting into my yard?
If a torpedograss segment gets into your lawn, it can grow into a full plant. These segments can be brought in by dirty lawn equipment, birds flying overhead, and tainted soils.
Torpedograss also can creep into your lawn from your neighbor’s lawn. There’s not much you can do if they can’t keep creeping panic under control.
Hire a pro to get rid of tough weeds
Torpedograss is one of those resilient weeds that are really difficult to kill off completely. You may need to turn to professionals who have the knowledge and tools to make it happen. Lawn Love can connect you with weed control pros in your area who can help.
Main Image Credit: Forest & Kim Starr | Wikimedia Commons | CC BY 3.0
