Ludwigia perennis: How to Spot and Control It in Rice Fields
Ludwigia perennis is a short, yellow flowered broadleaf weed that farmers call Kahoy kahoy, malapako, tina tina or sigang dagat. It grows in irrigated and rainfed lowland rice fields in the Philippines. This page shows you how to spot it among its look alike cousins and how to control it before it spreads.
What Is Ludwigia perennis?
In English, Ludwigia perennis is called perennial water primrose. It is part of the evening primrose family, Onagraceae. Farmers call it Kahoy kahoy, malapako, tina tina or sigang dagat. The first three names are shared with other Ludwigia weeds, so check the flowers closely. Being a broadleaf weed, it is not a grass or a sedge.
You will find it in both irrigated and rainfed lowland rice fields. Its English name says perennial, but the plant grows as an annual and finishes its life in one season. It spreads by seed and also by plant fragments. Broken pieces left on wet soil can grow into new plants. So rough weeding that leaves pieces behind can spread it further.
| Name | Ludwigia perennis |
|---|---|
| English name | Perennial water primrose |
| Family | Onagraceae |
| Weed group | Broadleaves (see the three groups) |
| Local names | Kahoy kahoy, malapako, tina tina, sigang dagat |
| Life cycle | Annual |
| Spreads by | Seeds and plant fragments |
| Where it grows | Irrigated and rainfed lowland rice fields |
How to Identify Ludwigia perennis
Look for a small, upright, branched plant up to 30 cm tall. The stems have uneven ridges and are sometimes reddish. Its leaves are narrow and lance shaped. Like other broadleaf weeds, the leaves have netted veins, unlike grasses and sedges. The yellow flowers have four or five egg shaped petals. Then count the stamens. They match the number of sepals, unlike the eight stamens of its bigger cousins. The seed pods have four angles and are reddish.
- Short, upright, branched plants no taller than about 30 cm.
- Stems with uneven, irregular ridges, sometimes with a reddish tinge.
- Narrow, lance shaped leaves growing along the stems and branches.
- Yellow flowers with four or five egg shaped petals.
- Look alike tip: it has as many stamens as sepals, while seedbox and Mexican primrose willow have eight.
- Reddish seed pods with four angles forming after the flowers drop.
Why It Hurts Your Palay
This weed is small, but it still takes a share of what your palay needs. It competes with rice for water, fertilizer and light, most of all while the rice is young and short. When many plants grow close together, the rice hills get crowded and grow weaker.
Because it spreads by seed and by plant fragments, careless weeding can make it worse. Broken pieces left in the mud can root again. Plants that set seed also fill the soil with seed for the next cropping. Some seed caught at harvest can end up in palay you save for planting, so the problem follows you.
A leaf beetle works on your side against this weed. The Altica beetle, from the chrysomelid family, feeds on it. Both its larvae and adults eat the leaves hungrily. When you find these beetles chewing kahoy kahoy leaves, leave them alone and avoid spraying insecticide there. They weaken the weed for free while you handle the rest.
How to Control Ludwigia perennis
- Pull whole plants with their roots and bring them out of the paddy, because broken fragments left in the mud can grow again.
- Weed before the flowers turn into reddish seed pods, since plants that set seed fill the soil for next season.
- Spare the Altica beetles you see eating its leaves, and avoid insecticide sprays where they feed.
- Because it stays short, it can hide below the rice leaves, so check low between the hills when you walk the field.
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 perennis 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 perennis 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 perennis?
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 perennis
What is this weed called in Tagalog and other local names?
How do I control it in a rice field?
Is Ludwigia perennis really an annual if its name says perennial?
Get Ludwigia perennis out of your field
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