Torpedo Grass in Rice Fields: How to Spot and Dig It Out
Torpedo grass is a creeping perennial grass weed of rainfed lowland rice fields and the bunds of irrigated fields in the Philippines. It spreads through tough underground rootstocks with sharp, pointed tips. This page shows how to spot it, how it hurts your palay and how to control it.
What Is Torpedo Grass?
Torpedo grass (Panicum repens) belongs to the grass family. Farmers know it by many local names, such as tagik tagik, buwag buwag, murag bermuda, maralaya, luy a luy a, sabilau and luya luyahan. A name like murag bermuda shows how often people mix it up with Bermuda grass. It grows in rainfed lowland rice fields and along the bunds of irrigated fields.
This weed is a perennial, so it lives on from season to season. It makes seeds, but it spreads mainly through its rootstocks. These are tough stems that run under the soil and end in sharp, pointed tips. Every broken piece can grow into a new plant. So plowing a patch can spread it across the whole paddy.
| Name | Torpedo grass |
|---|---|
| Scientific name | Panicum repens |
| Family | Poaceae (Graminae) |
| Weed group | Grasses (see the three groups) |
| Local names | Tagik tagik, buwag buwag, murag bermuda, maralaya, luy a luy a, sabilau, luya luyahan |
| Life cycle | Perennial |
| Spreads by | Seeds and rootstocks |
| Where it grows | Rainfed lowland rice fields and along bunds of irrigated fields |
How to Identify Torpedo Grass
Like other grasses, it has round, hollow stems with clear joints, or nodes. The stems stand upright and root at the nodes, which are smooth and hairless. The leaves are long, narrow, flat and slightly hairy. Its seed head is an open panicle with slender, upright branches. Small oval spikelets hang from thin stalks. Then dig around the base, and you will find the hard rootstocks with their sharp, pointed tips.
- Upright stems rise from creeping rootstocks and root at the smooth, hairless nodes.
- Leaves are long, narrow and flat, with a light coat of hairs.
- The open panicle has slender, upright branches with small oval spikelets on thin stalks.
- Underground stems end in hard, sharp tips that look like little torpedoes.
- Look alike tip: Bermuda grass has two or three leaves at each runner joint, while this grass does not.
- Patches often start on the bunds and creep into the paddy from the edges.
Why It Hurts Your Palay
As a perennial, this grass already has roots in the soil when you plant your rice. Its rootstocks hold stored food, so new shoots come up fast. Then they race your young palay for water, light and fertilizer. Thick patches crowd the rice hills along the field edges first, then move inward.
It also makes weeding slow and costly. Pulling the tops does not kill it, because the rootstocks stay alive in the soil. Each piece left behind sends up new shoots. On the bunds, it gives pests a place to hide between crops. Its seeds can also mix with your harvest when the patch reaches the rice.
How to Control Torpedo Grass
- Dig out each clump with all of its rootstocks. Follow the runners under the soil, since every piece left behind can regrow.
- Keep the bunds of irrigated fields clean, because this grass often grows there first and then creeps into the paddy.
- Rake rootstock pieces out after plowing and dry them in the sun on high ground, away from the field.
- Check cleared spots again after a few weeks, and dig out any new shoots while they are still small.
What to Do at Each Age of Your Rice
- 0 to 5 days: keep the soil saturated. Use a pre emergence herbicide only if the field had many weeds last season.
- 6 to 10 days: hand weed in transplanted rice. In direct seeded rice, this is the window for an early post emergence spray.
- 11 to 20 days: keep water in the field, weed by hand or with a rotary weeder, and let Azolla and the Altica beetle help. Spray only if those fail.
- 21 to 30 days: top up the water and keep weeding. Spray only if weeding fails.
- 31 to 40 days (transplanted rice): hand weed. A spray this late is only a rescue.
- After any post emergence spray, bring the water back within 1 to 3 days at 3 to 5 cm and hold it for 4 to 5 days. Keep young rice above it.
Active Ingredients That Work on Grasses
If water and weeding cannot hold torpedo grass down, choose an active ingredient that works on grasses at the age of your rice. Each active ingredient in it is in a herbicide registered in the Philippines for rice. Shop by the ingredient on the label, never by the brand. If your field also has other kinds of weeds, the weed control helper in anee.io finds the ingredients that cover all of them.
| Rice age (days after planting) | Transplanted rice (lipat tanim) | Direct seeded rice (sabog tanim) |
|---|---|---|
| 0 to 5 days | Butachlor, Pretilachlor, Oxadiazon, Butachlor plus 2,4 D IBE, Pendimethalin, Pyrazosulfuron ethyl plus pretilachlor, Clomazone, Penoxsulam plus butachlor, Tefuryltrione plus triafamone, Tetflupyrolimet, Thiobencarb plus 2,4 D IBE | Butachlor, Pretilachlor, Oxadiazon, Pretilachlor plus butachlor, Butachlor plus 2,4 D IBE, Pendimethalin, Pyrazosulfuron ethyl plus pretilachlor, Butachlor with safener, Clomazone, Tetflupyrolimet |
| 6 to 10 days | Butachlor plus propanil, Cyhalofop butyl plus bispyribac sodium, Bispyribac sodium, Penoxsulam plus cyhalofop butyl, Pendimethalin, Cyhalofop butyl plus propanil, Propyrisulfuron, Clomazone plus propanil, Thiobencarb plus propanil, Flucetosulfuron, Cyhalofop butyl plus florpyrauxifen benzyl | Butachlor plus propanil, Cyhalofop butyl plus bispyribac sodium, Bispyribac sodium, Cyhalofop butyl, Metamifop, Pyribenzoxim plus cyhalofop butyl, Penoxsulam plus cyhalofop butyl, Cyhalofop butyl plus propanil, Pyrazosulfuron ethyl plus pretilachlor, Pendimethalin, Propyrisulfuron, Clomazone plus propanil, Thiobencarb plus propanil, Pretilachlor plus pyribenzoxim, Penoxsulam, Flucetosulfuron, Cyhalofop butyl plus florpyrauxifen benzyl |
| 11 to 20 days | Cyhalofop butyl plus bispyribac sodium, Bispyribac sodium, Pyribenzoxim plus cyhalofop butyl, Penoxsulam plus cyhalofop butyl, Metamifop plus bispyribac sodium, Cyhalofop butyl plus ethoxysulfuron, Propyrisulfuron, Fenoxaprop P ethyl plus ethoxysulfuron, Flucetosulfuron, Florpyrauxifen benzyl, Cyhalofop butyl plus florpyrauxifen benzyl, Profoxydim | Cyhalofop butyl plus bispyribac sodium, Bispyribac sodium, Cyhalofop butyl, Metamifop, Pyribenzoxim plus cyhalofop butyl, Penoxsulam plus cyhalofop butyl, Metamifop plus bispyribac sodium, Pyribenzoxim, Cyhalofop butyl plus ethoxysulfuron, Propyrisulfuron, Fenoxaprop P ethyl plus ethoxysulfuron, Flucetosulfuron, Florpyrauxifen benzyl, Cyhalofop butyl plus florpyrauxifen benzyl, Profoxydim |
| 21 to 30 days | Metamifop plus bispyribac sodium, Fenoxaprop P ethyl plus ethoxysulfuron | Cyhalofop butyl plus bispyribac sodium, Metamifop, Pyribenzoxim plus cyhalofop butyl, Metamifop plus bispyribac sodium, Pyribenzoxim |
| 31 to 40 days | No herbicide listed at this age. Hand weed and keep the water up. | Not listed for direct seeded rice |
Spray Safely
Use only herbicides registered with the Fertilizer and Pesticide Authority, and follow the label on the pack: the rate, the timing, the water and the protective clothing. Switch herbicide groups between seasons so the weeds do not learn to survive them. Our guide to herbicides for rice explains the groups.
Keep Torpedo Grass Out Next Season
- Plant clean, certified seed. Weed seeds mixed into the punla are the easiest way in.
- Keep the seedbed, the canals and the bunds free of weeds, so seed does not wash or blow into the paddy.
- Plow and harrow well, and rake out the runners, roots or pieces you turn up. A small piece left in wet soil can grow a new plant.
- Pull escapes before the seed heads open, and clean the thresher and harvester before they enter the field.
- Keep the field clean after harvest and through the fallow, so fewer seeds build up in the soil for next season.
These steps work for every grass weed in the paddy, not only this one. The weed management guide puts them in order for a whole season.
Not Sure It Is Torpedo Grass?
Take a clear photo of the leaf, the stem and the flower or seed head, then ask Anee, the smart farm technician in anee.io, in Tagalog or English. Anee tells you which weed it most likely is, its group, and what to do at the age of your rice. You can also put the weeding days on your cropping calendar, so the team knows when to go in.
anee.io keeps your weeding, spraying and water on one calendar, and Anee answers when a plant looks wrong.
- Weeding days on the season calendar
- Photos and notes for every lot
- Anee, the smart farm technician, in Tagalog or English
Questions Farmers Ask About Torpedo Grass
What do farmers call torpedo grass in the Philippines?
How do I control it in my rice field?
Why does torpedo grass come back after plowing?
Get Torpedo Grass out of your field
With Libre + Anee, read the whole guide: how to tell it from your crop, and what to do and spray at every age of your crop.
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