Onion weed, also known as water onion or Scirpus grossus, is a perennial herbaceous plant in the Cyperaceae family. It is a common and troublesome weed in paddy fields. Failure to effectively control onion weed can have serious consequences on the growth and yield of rice. So, how can onion weed in paddy fields be prevented and controlled effectively? Let's find out.
How to Prevent and Control Onion Weed in Paddy Fields?
Choice of Herbicides for Onion Weed
Onion weed reproduces rapidly through rhizome propagation and seed reproduction, similar to wild taro. It is challenging to control due to its slender stems and smooth surface, making it difficult for herbicides to adhere. Therefore, the key to controlling onion weed lies in selecting the right herbicides. Commonly used herbicides include but are not limited to pendimethalin, alachlor, glyphosate, 2,4-D, paraquat, and atrazine. Before spraying, herbicides should be mixed with water according to the instructions, evenly sprayed onto the weeds, and after application, the water level should be restored. Approximately 2-3 days later, the onion weed will begin to wither and die.
Methods for Controlling Onion Weed
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Pre-closure and Plowing Before Transplanting Seedlings: Apply 2500 milliliters of 60% matrine per hectare, along with 300 grams of 10% pendimethalin, and then plow after application. Three days before transplanting seedlings, apply 2500 milliliters of 12% fenoxaprop-p-ethyl per hectare. This method effectively controls onion weed, Cyperus iria, wild taro, and barnyard grass, among other weeds.
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Closure and Application After Transplanting Seedlings: After 15-20 days of transplanting seedlings, apply 300 grams per hectare of 33% pendimethalin water dispersible granules, or 150-225 grams per hectare of 10% pendimethalin wettable powder using the soil poisoning method. Mix the herbicide uniformly with moist soil to create a toxic soil mixture, and apply it through furrow application, hole application, or broadcast application.
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Stem and Leaf Treatment: After the rice regrows, spray 200 milliliters of glyphosate per acre mixed with 30 kilograms of water onto the stems and leaves of onion weed. Alternatively, when the rice enters the late tillering stage, spray 20 grams per acre of 57% paraquat mixed with 30 kilograms of water to effectively control onion weed.
In summary, onion weed in paddy fields must be promptly prevented and controlled, and herbicides should be applied uniformly according to the plot map and standard dosage. However, onion weed, with its good ornamental value, can also be used for medicinal purposes, thereby realizing its economic value.
Frequently Asked Questions (FAQ)
1. How can I identify onion weed in paddy fields?
Onion weed (Scirpus grossus) can be identified by its slender, smooth stems and onion-like bulbs at the base. It typically grows in clusters in wet or flooded areas of paddy fields.
2. What are the adverse effects of onion weed on rice cultivation?
Onion weed competes with rice plants for nutrients, water, and sunlight, resulting in reduced rice yield. It can also interfere with the mechanical harvesting process and reduce the quality of harvested rice grains.
3. Are there any cultural practices that can help control onion weed?
Implementing proper land preparation techniques, such as plowing and leveling fields before planting, can help reduce the growth of onion weed. Additionally, maintaining proper water management practices, such as timely irrigation and drainage, can also suppress weed growth.
4. Can manual weeding be effective in controlling onion weed?
Manual weeding can be effective for controlling onion weed in small-scale or organic rice farming systems. However, it may not be practical for large-scale commercial rice cultivation due to labor and cost constraints.
5. How long does it take for herbicides to control onion weed effectively?
The effectiveness of herbicides in controlling onion weed can vary depending on factors such as the type of herbicide used, application rate, and environmental conditions. In general, visible symptoms of weed control, such as wilting and yellowing, may be observed within a few days to a week after herbicide application.
6. Are there any eco-friendly methods for controlling onion weed?
Yes, several eco-friendly methods can be used to control onion weed in paddy fields. These include the use of organic mulches, cover crops, and bioherbicides derived from natural sources. Additionally, integrated weed management practices, such as crop rotation and crop diversification, can help reduce reliance on chemical herbicides.
7. Can onion weed be used for any beneficial purposes?
While onion weed is primarily considered a weed in rice cultivation, it has some beneficial uses. In traditional medicine, certain parts of the plant are used for their medicinal properties. Additionally, onion weed can provide habitat and food for certain wildlife species.
8. What are the potential risks associated with herbicide use for controlling onion weed?
The use of herbicides for controlling onion weed may pose certain risks to human health, non-target organisms, and the environment if not used properly. Risks include herbicide residues in soil and water, herbicide drift to adjacent crops or water bodies, and development of herbicide-resistant weed populations.
9. Is crop rotation an effective strategy for managing onion weed?
Yes, crop rotation can be an effective strategy for managing onion weed in paddy fields. By rotating rice with non-host crops or cover crops, farmers can disrupt the weed's life cycle and reduce its population density over time.
10. How can farmers monitor and assess the effectiveness of onion weed control measures?
Farmers can monitor onion weed populations and assess the effectiveness of control measures through regular field inspections and weed density surveys. They can also collect data on weed biomass, weed seed production, and weed-related yield losses to evaluate the impact of control measures on weed management.
