Giant Bulrush: How to Spot and Control Tikiw in Your Rice Field
Giant bulrush, or Scirpus grossus, is a large sedge weed of irrigated and rainfed lowland rice fields in the Philippines. Farmers know it as tikiw. It spreads by seed and by rootstocks under the soil. This page shows how to spot it in your palay and how to control it so it does not come back.
What Is Giant Bulrush?
This damo is a sedge from the Cyperaceae family. Filipino farmers call it tikiw. As its English name says, giant bulrush is a big, tall sedge. It shows up in both irrigated and rainfed lowland rice fields, where it can stand above the palay around it.
Some plants live for one season only, while others keep growing as perennials. It spreads by seed and by rootstocks, which are thick underground stems at the base of the plant. Seeds drop into the soil and sprout with the next crop. Meanwhile, a rootstock left in the mud can send up new shoots after you cut the top. So pulling the leaves alone rarely ends the problem. You need to take out what lies below the soil as well.
| Name | Giant bulrush |
|---|---|
| Scientific name | Scirpus grossus |
| Family | Cyperaceae |
| Weed group | Sedges (see the three groups) |
| Local names | Tikiw |
| Life cycle | Annual, sometimes perennial |
| Spreads by | Seeds and rootstocks |
| Where it grows | Irrigated and rainfed lowland rice fields |
How to Identify Giant Bulrush
Like all sedges, it has a solid, triangular stem with no nodes. Roll the stem between your fingers and you will feel three clear edges. This plant grows tall and stout, so you can often spot it above the rice. At the top it carries many brown spikelets, each one egg shaped. Rice, on the other hand, has a round, hollow stem with joints.
- A thick, three sided stem that feels solid and has no joints.
- Tall plants standing out above the palay canopy.
- Many brown, egg shaped spikelets crowded at the top of the stem.
- New shoots rising from the same spot after cutting, a sign of living rootstocks.
Why It Hurts Your Palay
Like most sedges, giant bulrush competes with palay for light, water and fertilizer. Because it grows so big, it can shade the rice around it and take a large share of the nutrients. Where it forms clumps, fewer rice plants can grow in that space.
When it flowers, its seeds can mix with harvested palay and lower the quality of seed you keep. Plants that survive as perennials also come back crop after crop. Dense clumps give rats and insect pests a place to hide close to the rice hills.
How to Control Giant Bulrush
- Dig out each clump with its rootstocks, using a spade or bolo, because cut stems sprout again from what stays in the mud.
- Remove young plants early, while they are small and their rootstocks are still easy to pull.
- Cut and remove plants before the brown spikelets ripen, so they do not add seed to the field.
- Clear tikiw from canals and field edges too, since clumps there can spread back into the paddy.
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 giant bulrush 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 Giant Bulrush 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 Giant Bulrush?
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 Giant Bulrush
What do Filipino farmers call giant bulrush?
How do I control it in my rice field?
Why does tikiw keep coming back after I cut it?
Get Giant Bulrush out of your field
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