Ludwigia octovalvis: How to Spot and Control It in Rice Fields
Ludwigia octovalvis is a tall broadleaf weed with big yellow flowers that farmers call Kahoy kahoy, malapako or tina tina. It grows in irrigated and rainfed lowland rice fields in the Philippines, and it is a special problem in dry seeded rice. This page shows you how to spot it and how to control it before it towers over your palay.
What Is Ludwigia octovalvis?
In English, Ludwigia octovalvis is called Mexican primrose willow. It comes from the evening primrose family, Onagraceae. Farmers know it as Kahoy kahoy, malapako or tina tina, the same names used for its smaller cousins. Since it is a broadleaf weed, it is neither a grass nor a sedge.
You will see it in both irrigated and rainfed lowland rice fields. Some plants act as annuals and die after one season, while others live on as perennials. It spreads by seed and by propagules, which are plant parts that can grow on their own. Left alone, a plant can reach 3 m in height, so it gets much harder to pull once it is big.
| Name | Ludwigia octovalvis |
|---|---|
| English name | Mexican primrose willow |
| Family | Onagraceae |
| Weed group | Broadleaves (see the three groups) |
| Local names | Kahoy kahoy, malapako, tina tina |
| Life cycle | Annual or perennial |
| Spreads by | Seeds and propagules |
| Where it grows | Irrigated and rainfed lowland rice fields |
How to Identify Ludwigia octovalvis
This is a big, sturdy kahoy kahoy weed. It stands upright, branches out, and can grow up to 3 m tall. The stems are ridged and sometimes reddish, and the leaves are lance shaped. As a broadleaf weed, its leaves have netted veins, unlike grasses and sedges. The flowers are big and yellow, with four broad, oval petals and eight stamens. Its seed pods are larger than those of its cousins, with four angles and a reddish color.
- Tall, branched plants that can reach 3 m and rise far above the palay.
- Upright stems with ridges along their length, sometimes with a reddish color.
- Big yellow flowers with four broad, oval petals and eight stamens.
- Large, reddish seed pods with four angles forming along the branches.
- Look alike tip: its big yellow flowers set it apart from Ludwigia hyssopifolia and Ludwigia perennis.
- Thick stands in dry seeded rice fields, where this weed is known to invade.
Why It Hurts Your Palay
Ludwigia octovalvis is a serious weed of rice. Out of 350 weed species found in rice fields around the globe, it ranks fourth in importance among the broadleaves. It invades many kinds of rice culture, but it is a special problem in dry seeded rice.
Because it grows so tall, it shades the palay and steals the light the rice needs. It also competes for water and fertilizer. Its big seed pods add more seed to the soil each season. So the longer it stays, the bigger the stand you will have to fight next cropping.
You have a free helper against this weed. The Altica beetle, a small leaf beetle from the chrysomelid family, attacks it. Its larvae and adults feed hungrily on the leaves. So when you see these beetles chewing kahoy kahoy leaves, do not spray them. Let them keep weakening the weed while you do the hand weeding.
How to Control Ludwigia octovalvis
- Pull or cut plants while they are still short, since a plant growing toward 3 m gets tough and hard to remove.
- In dry seeded rice, weed early and check often, because this weed invades dry seeded fields more than other rice cultures.
- Leave the Altica beetles that feed on its leaves, and avoid needless insecticide sprays that would kill these helpers.
- Cut or pull plants before the big reddish pods ripen, then bring them out of the paddy so no seed drops.
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 Ludwigia octovalvis 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 Ludwigia octovalvis 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 Ludwigia octovalvis?
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 Ludwigia octovalvis
What is Ludwigia octovalvis called in the Philippines?
How do I control this weed in a rice field?
Why is it such a big problem in dry seeded rice?
Get Ludwigia octovalvis out of your field
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