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UPSC MainsAGRICULTURE-PAPER-I202410 Marks
Q18.

Describe in detail about the weed control measures in Black Gram and Sesame.

How to Approach

This question requires a detailed discussion of weed control measures in black gram (urad) and sesame (til). A structured approach is essential, first defining the problem of weeds in these crops, then outlining preventative measures, followed by manual, mechanical, chemical, and biological control methods for each crop. Comparative analysis of the suitability of different methods for each crop will enhance the answer. Finally, highlighting integrated weed management practices is crucial. The answer should demonstrate an understanding of agronomic principles and the latest advancements in weed control.

Model Answer

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Introduction

Weeds pose a significant threat to agricultural productivity globally, and black gram (Urad, *Vigna mungo*) and sesame (Til, *Sesamum indicum*) are no exception. These crops, vital for dietary diversity and oilseed production in India, are particularly susceptible to weed competition during their early growth stages. The loss due to weeds can range from 20% to 70% depending on weed density and crop stage. Effective weed control is therefore paramount for ensuring optimal yields and farmer profitability. This response will detail the various weed control measures applicable to both black gram and sesame, encompassing preventative, manual, mechanical, chemical, and biological approaches, alongside integrated management strategies.

Understanding the Weed Problem in Black Gram and Sesame

Both black gram and sesame are sensitive to weed competition, especially during the first 30-45 days of growth. Weeds compete for nutrients, water, sunlight, and space, hindering crop establishment and yield. Common weeds found in black gram fields include Echinochloa crus-galli (barnyard grass), Cyperus rotundus (nutgrass), and Polygonum spp. Sesame fields are often infested with Portulaca oleracea (purslane), Chenopodium album (lambsquarters), and Digitaria spp (crabgrass).

Preventative Weed Control Measures

  • Crop Rotation: Rotating with non-leguminous crops helps to break weed cycles.
  • Clean Seed: Using weed-free seeds minimizes initial weed infestation.
  • Summer Plowing: Exposing weed seeds to sunlight and predation through summer plowing.
  • Balanced Fertilization: Proper nutrient management can promote vigorous crop growth, suppressing weed competition.

Weed Control Measures in Black Gram

Manual & Mechanical Control

  • Hand Weeding: Effective for small areas but labor-intensive.
  • Intercultivation: Using hoes or cultivators to uproot weeds between rows. This is most effective when done early.
  • Mulching: Using organic materials (straw, crop residues) to suppress weed growth and conserve moisture.

Chemical Control

  • Pre-emergence Herbicides: Examples include Pendimethalin, Butachlor. Application before weed emergence. Dosage varies based on soil type and weed species.
  • Post-emergence Herbicids: Examples include MCPA, 2,4-D. These are selective and need to be used carefully to avoid crop damage. The "Weed-Free Crop Initiative" promotes judicious herbicide use.

Biological Control

  • Cover Cropping: Using fast-growing cover crops like sunn hemp to suppress weeds.
  • Bioherbicides: Research is ongoing on using plant-derived compounds or microorganisms to control weeds.

Weed Control Measures in Sesame

Manual & Mechanical Control

  • Hand Weeding: Essential for sesame as it is a low-growing crop, making mechanical weeding difficult.
  • Intercultivation: Can be done cautiously to avoid damaging the sesame plants.

Chemical Control

  • Pre-emergence Herbicides: Bentazon is commonly used but requires careful application to avoid phytotoxicity.
  • Post-emergence Herbicides: Glufosinate-ammonium can be used for broad-spectrum weed control, but application timing is critical.

Biological Control

  • Weed Seed Predators: Promoting natural enemies like birds and insects that feed on weed seeds.
  • Mycoherbicides: Utilizing fungal pathogens specific to certain weed species.

Comparison Table: Weed Control Measures

Method Black Gram Suitability Sesame Suitability Advantages Disadvantages
Hand Weeding Moderate High Effective, environmentally friendly Labor-intensive, costly
Mechanical Cultivation High Low Efficient for large areas Can damage crop, limited applicability in sesame
Pre-emergence Herbicides High Moderate Easy to apply, broad-spectrum Potential for herbicide resistance
Post-emergence Herbicides Moderate Low Targeted weed control Phytotoxicity risk, environmental concerns

Integrated Weed Management (IWM)

IWM combines multiple control methods to maximize effectiveness and minimize environmental impact. For both black gram and sesame, IWM should include:

  • Preventive measures (crop rotation, clean seed)
  • Early hand weeding or mechanical cultivation
  • Judicious use of herbicides
  • Biological control methods
  • Monitoring weed populations and adapting strategies accordingly
Effective weed control in black gram and sesame is crucial for ensuring sustainable yields and farmer livelihoods. While manual and mechanical methods remain essential, particularly in sesame cultivation, the judicious use of herbicides and the exploration of biological control agents are increasingly important. An integrated approach, combining preventative measures with targeted interventions, offers the most sustainable and effective solution for managing weeds in these vital crops. Further research into bioherbicides and weed seed predators holds promise for environmentally friendly weed control in the future.

Conclusion

Effective weed control in black gram and sesame is crucial for ensuring sustainable yields and farmer livelihoods. While manual and mechanical methods remain essential, particularly in sesame cultivation, the judicious use of herbicides and the exploration of biological control agents are increasingly important. An integrated approach, combining preventative measures with targeted interventions, offers the most sustainable and effective solution for managing weeds in these vital crops. Further research into bioherbicides and weed seed predators holds promise for environmentally friendly weed control in the future.

Answer Length

This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.

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Additional Resources

Key Definitions

Phytotoxicity
The harmful effect of a chemical substance (like a herbicide) on a plant.
Bioherbicide
A biological herbicide that uses living organisms (bacteria, fungi, viruses, etc.) or their byproducts to control weeds.

Key Statistics

Weed competition can cause yield losses of up to 70% in black gram and 40-50% in sesame, especially under rainfed conditions. (Source: ICAR-Indian Institute of Pulses Research, 2023 - Knowledge Cutoff)

Source: ICAR-IIPR

The adoption rate of herbicides in black gram cultivation is approximately 60-70% across major growing regions in India. (Source: Directorate of Economics and Statistics, 2022 – Knowledge Cutoff)

Source: DES

Examples

Bentazon Application in Sesame

Bentazon, a pre-emergence herbicide, is commonly used in sesame but requires precise application timing and rates to avoid crop damage. Excessively high doses can cause leaf curling and stunted growth.

Frequently Asked Questions

▶Why is hand weeding more important in sesame than in black gram?

Sesame is a low-growing crop, making mechanical weeding difficult and less effective. Black gram has a more robust growth habit, allowing for easier intercultivation.

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