Scirpus juncoides: How to Spot and Control Rock Bulrush in Rice
Scirpus juncoides, or rock bulrush, is a slender sedge weed of irrigated and rainfed lowland rice fields in the Philippines. Farmers call it apulid, bitubituinan or balbas kalabaw. It spreads by tillers and by seed. This page shows how to spot it among your palay and how to control it before it spreads.
What Is Scirpus juncoides?
This damo is a sedge from the Cyperaceae family. Its English name is rock bulrush, and Filipino farmers know it as apulid, bitubituinan or balbas kalabaw. You will find Scirpus juncoides in both irrigated and rainfed lowland rice fields.
Some plants live for one season, while others keep going as perennials. It spreads in two ways. First, it makes tillers, which are new shoots from the base, so one plant slowly becomes a thick clump. Second, it produces seeds that fall into the soil. When ripe, these small fruits turn brown to black. Because both tillers and seeds keep it going, it pays to weed it early and completely. A young plant with one shoot comes out far more easily than an old clump.
| Name | Scirpus juncoides |
|---|---|
| English name | Rock bulrush |
| Family | Cyperaceae |
| Weed group | Sedges (see the three groups) |
| Local names | Apulid, bitubituinan, balbas kalabaw |
| Life cycle | Annual or perennial |
| Spreads by | Tillers and seeds |
| Where it grows | Irrigated and rainfed lowland rice fields |
How to Identify Scirpus juncoides
Like other sedges, it has a solid stem with no nodes, though here the stem is slender and nearly round. The stems stand erect and grow in a tight clump. Its leaves have shrunk into sheaths that wrap around the base of the stems. So from a distance the plant looks almost leafless, like a bunch of green straws. When mature, its fruits turn broadly oval and brown to black.
- Slender, erect stems in tight clumps, with no joints along their length.
- Leaves shrunk into sheaths that wrap only the base of the stems.
- A plant that looks almost leafless, like a bunch of green straws.
- Mature fruits that are broadly oval and brown to black.
- New shoots, or tillers, rising from the base and widening the clump.
Why It Hurts Your Palay
Like most sedges, Scirpus juncoides competes with palay for light, water and fertilizer. Because it tillers, each plant grows into a clump that takes up more room between the rice hills. Clumps that live on as perennials keep using your soil from one crop to the next.
Its seeds add to the weed seed bank in the field, so missed plants mean more weeds next season. Seeds can also mix with harvested palay and lower the quality of seed you keep. Dense clumps can shelter insect pests close to the rice hills too.
How to Control Scirpus juncoides
- Pull young plants before they tiller, while each one is still a single shoot and easy to remove.
- Dig out older clumps with their whole base, since leftover tillers can keep the clump alive.
- Weed before the fruits turn brown to black, so mature seeds do not fall into the soil.
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 Sedges
If water and weeding cannot hold Scirpus juncoides down, choose an active ingredient that works on sedges 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, Pyrazosulfuron ethyl plus pretilachlor, Imazosulfuron, Penoxsulam plus butachlor, Tefuryltrione plus triafamone, Thiobencarb plus 2,4 D IBE | Butachlor, Pretilachlor, Oxadiazon, Pretilachlor plus butachlor, Butachlor plus 2,4 D IBE, Pyrazosulfuron ethyl plus pretilachlor, Butachlor with safener |
| 6 to 10 days | Butachlor plus propanil, Cyhalofop butyl plus bispyribac sodium, Bispyribac sodium, Penoxsulam plus cyhalofop butyl, Imazosulfuron, Propyrisulfuron, Clomazone plus propanil, Thiobencarb plus propanil, Flucetosulfuron, Cyhalofop butyl plus florpyrauxifen benzyl | Butachlor plus propanil, Cyhalofop butyl plus bispyribac sodium, Bispyribac sodium, Pyribenzoxim plus cyhalofop butyl, Penoxsulam plus cyhalofop butyl, Pyrazosulfuron ethyl plus pretilachlor, 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, Bentazone, Cyhalofop butyl plus ethoxysulfuron, Propyrisulfuron, Fenoxaprop P ethyl plus ethoxysulfuron, Flucetosulfuron, Carfentrazone ethyl, Florpyrauxifen benzyl, Cyhalofop butyl plus florpyrauxifen benzyl | Cyhalofop butyl plus bispyribac sodium, Bispyribac sodium, Pyribenzoxim plus cyhalofop butyl, Penoxsulam plus cyhalofop butyl, Metamifop plus bispyribac sodium, Bentazone, Pyribenzoxim, Cyhalofop butyl plus ethoxysulfuron, Propyrisulfuron, Fenoxaprop P ethyl plus ethoxysulfuron, Flucetosulfuron, Carfentrazone ethyl, Florpyrauxifen benzyl, Cyhalofop butyl plus florpyrauxifen benzyl |
| 21 to 30 days | 2,4 D amine, 2,4 D IBE, MCPA, Metamifop plus bispyribac sodium, Bentazone, Metsulfuron methyl plus chlorimuron ethyl, Fenoxaprop P ethyl plus ethoxysulfuron, Carfentrazone ethyl | 2,4 D amine, 2,4 D IBE, Cyhalofop butyl plus bispyribac sodium, Pyribenzoxim plus cyhalofop butyl, MCPA, Metamifop plus bispyribac sodium, Bentazone, Metsulfuron methyl plus chlorimuron ethyl, Pyribenzoxim, Carfentrazone ethyl |
| 31 to 40 days | Metsulfuron methyl plus chlorimuron ethyl | 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 Scirpus juncoides 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 their flower clusters turn brown, since one clump drops a great deal of tiny seed.
- 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 sedge weed in the paddy, not only this one. The weed management guide puts them in order for a whole season.
Not Sure It Is Scirpus juncoides?
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 Scirpus juncoides
What do farmers call Scirpus juncoides in Tagalog and other local languages?
How do I control it in my rice field?
How does it spread in a rice field?
Get Scirpus juncoides 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.
The account is free, no credit card.
