Carabao Grass in Rice Fields: How to Spot and Control It
Carabao grass is a creeping perennial grass weed of rainfed lowland rice fields in the Philippines. It spreads on long, flat, reddish purple runners and ends in a pair of slender spikes. This page shows how to spot it, how it hurts your palay and how to control it before it forms a thick mat.
What Is Carabao Grass?
Carabao grass (Paspalum conjugatum) belongs to the grass family. Its local names include kauat kauat, lakatan, maligoy, pad pad, kolokawayan, bantotan, kulape and laau laau. In rice farming, it shows up in rainfed lowland fields, where water does not always stand in the paddy. It is also a familiar sight on bunds, paths and grazing land.
This weed is a perennial, so it does not die at the end of the season. It spreads by seed and also by stem cuttings. Its long runners creep across the ground and can take root along the way. When a hoe or a plow cuts these runners, each piece can root again and start a new patch.
| Name | Carabao grass |
|---|---|
| Scientific name | Paspalum conjugatum |
| Family | Poaceae (Graminae) |
| Weed group | Grasses (see the three groups) |
| Local names | Kauat kauat, lakatan, maligoy, pad pad, kolokawayan, bantotan, kulape, laau laau |
| Life cycle | Perennial |
| Spreads by | Seeds and stem cuttings |
| Where it grows | Rainfed lowland rice fields |
How to Identify Carabao Grass
Like other grasses, it has jointed stems with clear nodes, but its runners are flat rather than round. They creep a long way, often reddish purple, with hairy nodes. The leaves are flat and narrow, with hairs on the blades and sheaths. A collar of fine hairs sits just below each leaf blade. The ligule is short with a flat top, backed by a ring of hairs. At the top, two slender spikes branch apart, carrying blunt spikelets.
- Long, flat runners creep over the soil and show a reddish purple color.
- The joints along each runner carry a fringe of fine hairs.
- Leaf blades and sheaths are hairy, with a collar of fine hairs below each blade.
- The short, squared ligule has a ring of hairs on its back.
- Each seed head ends in two slender spikes that branch apart at the tip.
- Look alike tip: knotgrass also has paired spikes, but they stand upright like a Y, while these spread wide.
Why It Hurts Your Palay
Carabao grass forms a thick, low mat. Where it takes hold, it covers the soil and keeps taking water, light and fertilizer that your palay needs. Since it is a perennial, old patches are already growing when you plant. So your young rice has to compete from the very first day.
It is also hard to clear. Cutting or plowing breaks its runners into pieces, and each piece can root again. As a result, careless weeding can spread it even further. Thick mats on bunds and field edges can give rice pests a place to hide between crops. Its seeds can also end up in your harvest.
How to Control Carabao Grass
- Lift whole runners out by hand or with a hoe, then carry them off the field. Pieces left on moist soil can root again.
- Clean the bunds and paths around your paddy, since its runners creep from there into the field.
- Keep water in the paddy when you can. This grass grows best on moist soil, so standing water helps hold it back.
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 carabao 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 Carabao 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 Carabao 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 Carabao Grass
What do farmers call carabao grass in local languages?
How do I control it in my rice field?
Can my carabao or cattle eat it?
Get Carabao 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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