What herbicide works well on threeleaf sedge in paddy fields

In paddy fields, a weed called threeleaf sedge can generally be seen. It has strong reproductive capacity, brings considerable impact on rice growth, and can also provide breeding grounds for pests and diseases. When planting rice, it must be completely removed. What herbicide should be used for threeleaf sedge in rice?

I. What herbicide should be used for threeleaf sedge in rice

Before sowing rice, glyphosate can be sprayed, or pretilachlor plus bensulfuron-methyl can be used as a pre-emergence closed herbicide; for post-emergence weed control, agents such as pyrazosulfuron-ethyl, MCPA, and bentazone can be selected.

II. Key points for using herbicides in paddy fields

1. Understand the growth habits and occurrence patterns of various weeds. The first weed germination peak appears 7-10 days after transplanting; these weeds are mainly grass-family weeds such as Chinese sprangletop and barnyardgrass, and annual sedge-family weeds such as difformed galingale. The second germination peak appears 20 days after transplanting; these weeds are mainly sedge-family weeds and broadleaf weeds.

2. Choose suitable herbicides according to the paddy field and weed types. Seedling fields, direct-seeded fields, and seedling-throwing fields must not use herbicides containing acetochlor or metsulfuron-methyl, such as Lecao Long, Jingke Caoxing, Daocao Wei, and Miecao Wang; these herbicides are only suitable for manually transplanted paddy fields and machine-transplanted fields. If the paddy field type is not clearly distinguished and herbicides are used indiscriminately, the expected results are often not achieved. Some herbicides are only effective against monocotyledonous weeds such as barnyardgrass, and some herbicides can only kill dicotyledonous weeds such as monochoria. When carrying out chemical weed control in paddy fields, it is necessary to understand the weed-killing spectrum of the herbicide and the species distribution of weeds in the field.

3. The timing of weed control must be well grasped. Choose to apply the herbicide during the period when weeds are most sensitive to it, so as to improve the weed control effect. Choose to apply the herbicide during the growth stage when rice has the strongest tolerance to the herbicide, so as to ensure the safety of the rice seedlings. Generally speaking, weeds are most sensitive to herbicides at the seed germination stage and seedling stage, and herbicides are most likely to exert their efficacy; rice is most sensitive to herbicides at the bud stage and before the 4-leaf stage, and is prone to herbicide damage, so when applying herbicides at these growth stages, attention should be paid to the concentration of the agent. The application time of any herbicide must be combined with the rice transplanting time.

4. Fields using chemical herbicides must first be leveled and kept with a 3-4 cm deep water layer; application is required within a certain period, and after application a certain depth of water layer should still be maintained for 3-4 days. Generally speaking, in paddy fields with high organic matter content, the soil has a strong adsorption effect on herbicides, so the dosage can be increased as appropriate; when the temperature is high, the efficacy of herbicides is easily exerted, so the dosage should be appropriately reduced, and otherwise appropriately increased; when the dew has not dried, it is not suitable to apply the herbicide, especially not suitable to broadcast herbicide soil, so as to avoid too much agent adhering to rice leaves and causing herbicide damage. The intensity of light also has a great influence on herbicides. Substituted urea and triazine herbicides are typical photosynthesis inhibitors; if several days of strong light occur after application, the weed control effect can be improved, while sodium pentachlorophenate easily decomposes when exposed to light, so it is suitable for use on cloudy days.

The application of herbicides must be reasonable, and at the same time suitable agents should be selected according to local actual conditions.