Monochoria vaginalis: How to Spot and Control Gabi Gabi in Rice
Monochoria vaginalis is a shiny, soft broadleaf weed that farmers call gabi gabi, because its heart shaped leaves look like small taro leaves. It grows in both irrigated and rainfed lowland rice fields across the Philippines. On this page, you will learn how to spot it early, how much it can cost your palay, and how to control it before it spreads.
What Is Monochoria vaginalis?
Monochoria vaginalis goes by gabi gabi or gabi gabihan in many barangays. It is a fleshy, semi aquatic plant from the water hyacinth family, Pontederiaceae. It is a monocot, but it sits in the broadleaf group because its leaves are wide and heart shaped, not thin like grass blades. Since it loves wet, muddy soil, you find it in irrigated and rainfed lowland rice fields.
Most plants live for one season, but some survive longer and act as perennials. It spreads by seeds and by small tubers in the soil. Its seeds also do not sprout all at once. Some come up early, while others wait in the mud and come up later. That is why one round of weeding rarely clears it for the whole season.
| Name | Monochoria vaginalis |
|---|---|
| English name | Heartshape false pickerelweed |
| Family | Pontederiaceae |
| Weed group | Broadleaves (see the three groups) |
| Local names | Gabi gabi, gabi gabihan |
| Life cycle | Annual, sometimes perennial |
| Spreads by | Seeds and Tubers |
| Where it grows | Irrigated and rainfed lowland rice fields |
How to Identify Monochoria vaginalis
Look for a shiny, soft plant standing in the water between your rice hills. Its stems are soft and upright, and they send out roots at the nodes. The leaves have a heart shape and sit on soft, hollow leaf stalks. Unlike grasses and sedges, it has wide leaves, but its veins curve along the leaf instead of forming a net. When it flowers, long stalks carry lilac blue or violet flowers in small groups.
- Shiny, soft plants standing in the water between rice hills, glossy even from a distance.
- Heart shaped leaves on soft, hollow stalks that look like tiny gabi leaves.
- Soft, upright stems that send out roots wherever a node touches the mud.
- Long flower stalks carrying lilac blue or violet flowers in small groups of 2 to 6.
- New seedlings that keep coming up weeks after your last round of weeding.
Why It Hurts Your Palay
Gabi gabi may look harmless, but it fights your palay for light, water and fertilizer. At 100 plants per square meter, competing with rice from day 7 to day 40, it cut rice yield by 16 percent. When the same number of plants stayed until the crop matured, the loss climbed to 25 percent.
It is a C3 plant, and its seeds do not all sprout at the same time. Some come up early, while others wait. So a field that looks clean after one weeding can fill up again. That is how this weed slips past your control work and keeps stealing from your harvest.
How to Control Monochoria vaginalis
- Pull young plants by hand and lift out the base, because tubers left in the mud can sprout new plants.
- Plan more than one round of weeding. Its seeds sprout at different times, so check the field again a few weeks after your first pass.
- Remove plants before the violet flowers set seed, so fewer seeds drop into the mud for the next season.
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 Broadleaves
If water and weeding cannot hold Monochoria vaginalis down, choose an active ingredient that works on broadleaves 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 | 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 | Pretilachlor, Oxadiazon, Pretilachlor plus butachlor, Butachlor plus 2,4 D IBE, Pendimethalin, 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, Pendimethalin, Cyhalofop butyl plus propanil, 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, 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, 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 Monochoria vaginalis 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 they flower and set seed, and carry them out of the paddy instead of leaving them on the bund.
- 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 broadleaf weed in the paddy, not only this one. The weed management guide puts them in order for a whole season.
Not Sure It Is Monochoria vaginalis?
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 Monochoria vaginalis
What is Monochoria vaginalis called in Tagalog?
How do I control gabi gabi in my rice field?
Why does gabi gabi keep coming back after weeding?
Get Monochoria vaginalis out of your field
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