Here are all 68 Weeds questions asked in UPSC Agriculture Optional Paper I from 1995 to 2026, arranged under the 2 topics of the official syllabus. Within each topic the latest questions come first.
Each question ends with a code such as [2024/15m/3b] – the year, the marks, the word limit (where UPSC set one) and the question number in the paper.
4.1] Weeds: characteristics, dissemination and association with crops
19 questions
Write down the dissemination of weeds with appropriate examples. [2026/10m/150w/1d]
Explain weed seed bank. Describe the strategies to reduce weed seeds in soil. [2025/20m/4b]
Classify the parasitic weeds on the basis of their parasitism. Explain the preventive measures and integrated management practices for Orobanche. [2023/20m/2b]
Describe the causes of increasing threats of Parthenium weed in the country. Write integrated methods of weed management with suitable examples. [2020/20m/3b]
Define crop weed competition. Describe various factors affecting crop weed competition. Explain the factors affecting the efficacy of herbicides. [2020/20m/7a]
Describe crop-weed-competition. Discuss the different factors affecting the efficiency of herbicides. [2017/20m/4a]
Explain the critical period of crop-weed competition with suitable examples. [2016/10m/3c]
Describe crop-weed competition. [2014/20m/4c]
Discuss the factors affecting crop-weed competition. What do you mean by critical period of crop-weed competition? [2013/10m/200w/2b]
Relative and Obnoxious weeds. [2013/10m/150w/3c]
Persistence of weeds. [2013/12.5m/200w/8a]
What is crop-weed competition? Give principles of integrated weed management. [2012/12m/150w/1b]
Seed Dormancy. [2009/20m/200w/1c]
Allelopathy. [2007/20m/200w/1a]
Allelopathy. [2001/20m/200w/1b]
Relative & Obnoxious weeds. [2001/15m/8b]
What is crop-weed competition? Examine the significance of critical period of weed control. Critically assess the use of herbicides in weed control in rice and wheat. [1999/60m/3]
Define plant ecology. Discuss the role of autotoxicity in crop production. [1997/60m/3]
Enumerate the ill-effects of weed competition in field crops and briefly describe the methods of their control. [1995/60m/3]
Preparing for Prelims too?
Our UPSC Prelims Topic-wise PYQ eBook covers every Prelims question with detailed explanations, so you can see exactly where UPSC asks from.
View the BookDownload Free Sample4.2] Weed control
49 questions
Suggest suitable chemical weed management practices for the following crops: (i) Maize (ii) Moong (iii) Cotton (iv) Sugarcane. [2026/10m/3c]
Explain weed control efficiency (WCE). Work out WCE from the given data and offer your critical comment:
| Sl. No. | Treatment | Weed Population/m² |
| 1 | T₁–Unweeded check | 90 |
| 2 | T₂–Hand weeding | 55 |
| 3 | T₃–Herbicide A | 45 |
| 4 | T₄–Herbicide B | 40 |
| 5 | T₅–Herbicide C | 50 |
[2025/10m/150w/1e]
Explain weed seed bank. Describe the strategies to reduce weed seeds in soil. [2025/20m/4b]
Enumerate the harmful effects of herbicide residues in soil. Discuss the remedial measures to overcome the above problem. [2025/20m/6a]
Discuss the cultural methods of weed control. [2024/10m/150w/1d]
Describe in detail about the weed control measures in Black Gram and Sesame. [2024/10m/4c]
Briefly write about cultural and chemical weed control methods of soybean and wheat. [2023/10m/150w/1d]
Classify the parasitic weeds on the basis of their parasitism. Explain the preventive measures and integrated management practices for Orobanche. [2023/20m/2b]
Discuss selection criteria of successful bioagent and bio-herbicides. State at least two examples of biocontrol of weeds. [2022/10m/150w/1d]
Discuss about the types of herbicide resistance in weeds with specific example in Indian perspective. Discuss the management practices dealing with herbicide resistance in weeds. [2022/20m/4a]
The major weeds of rice and their management practices under both upland and lowland conditions. [2021/10m/150w/1d]
Discuss the activity and selectivity of herbicides. [2021/10m/2c]
Describe the major biological control methods of weeds. [2021/10m/4c]
Describe the causes of increasing threats of Parthenium weed in the country. Write integrated methods of weed management with suitable examples. [2020/20m/3b]
Define crop weed competition. Describe various factors affecting crop weed competition. Explain the factors affecting the efficacy of herbicides. [2020/20m/7a]
Current status of biological weed management. [2019/10m/150w/1e]
Differentiate the following with example:
(i) Catch crop and trap crop. [2019/5m/2a(i)]
(ii) Narrow spectrum and broad spectrum herbicides. [2019/5m/2a(ii)]
(iii) Fodder and forage crops. [2019/5m/2a(iii)]
(iv) Social forestry and agroforestry. [2019/5m/2a(iv)]
Calculate weed index in wheat crop with the given information and draw the inference.
| Treatment | Dose (gai/ha) | Grain yield (Kg/ha) |
| T₁ – Sulfosulfuron | 25 | 5,200 |
| T₂ – Isoproturon | 750 | 5,000 |
| T₃ – 2,4-D | 500 | 4,500 |
| T₄ – Weed free | Two Hand Weeding | 5,500 |
[2019/10m/3c]
What is the phenomenon of herbicide resistance in weeds? Discuss the factors responsible for development of herbicide resistance. [2018/10m/4c]
Innovations in biological weed management. [2018/10m/150w/5a]
What are the advances in chemical weed management? [2018/10m/8d]
Describe the method of biological weed control with suitable examples. [2017/10m/2c]
Describe crop-weed-competition. Discuss the different factors affecting the efficiency of herbicides. [2017/20m/4a]
Decoy crop vs Trap crop. [2016/10m/150w/1d]
List out the factors affecting efficacy of herbicides. [2016/10m/4c]
Discuss about the factors affecting the efficacy of herbicides. [2015/20m/2b]
Write the approaches of biological weed control with suitable examples. [2015/15m/4c]
Elaborate the problems of residual toxicity of herbicide and its management. [2015/10m/150w/5c]
Describe biological weed control with suitable example. [2014/10m/150w/1e]
Write the importance of quarantine check of weed seeds in importing foodgrain. [2014/10m/3b]
Write about the factors of development of herbicide resistance in weeds. What are the management options? [2013/15m/250w/4b]
Mode of herbicidal action. [2013/10m/150w/6b]
What is crop-weed competition? Give principles of integrated weed management. [2012/12m/150w/1b]
What are the factors of herbicide selectivity? Briefly discuss about selective herbicides for rice and wheat. [2012/15m/200w/4b]
Biological weed control. [2011/15m/150w/1d]
Selective and non-selective herbicides. [2011/10m/3e]
Herbicide Residue Management. [2009/20m/200w/1b]
Define integrated weed management. Suggest integrated weed management for rice-wheat, and groundnut-pigeon pea, inter-cropping systems. [2007/60m/6]
Weed control in wheat. [2006/20m/200w/1d]
Biological methods of weed control. [2005/20m/200w/1a]
Biological control of weeds. [2004/15m/200w/1d]
Classify herbicides used for weed control with examples. Discuss the advantages and limitations of using herbicides in crop production. What precautions should be taken during their application? [2004/60m/3]
What are the losses caused by weeds? Suggest chemical control of weeds in direct sown and transplanted rice, wheat, maize, sugarcane and soybean. [2003/60m/3]
Integrated Weed Control in Wheat. [2000/20m/200w/1c]
Classification of Herbicides. [2000/20m/200w/5b]
What is crop-weed competition? Examine the significance of critical period of weed control. Critically assess the use of herbicides in weed control in rice and wheat. [1999/60m/3]
Discuss the weed menace in upland rice and suggest management methods. [1998/60m/3]
Classify the herbicides used for weed control in field crops. Discuss the integrated weed management practices for paddy-wheat rotation of North-Western India. [1996/60m/4]
Enumerate the ill-effects of weed competition in field crops and briefly describe the methods of their control. [1995/60m/3]
Strengthen your GS papers
Our UPSC Mains Topic-wise & Year-wise PYQ eBook (2013–2026) maps every GS question to the syllabus, so you know what UPSC asks and how often.
View the BookDownload Free SampleSpotted an error? Tell us.
We classify every PYQ with care, but mistakes can slip in. If a question is in the wrong topic, has a typo, the wrong year, or is missing, let us know. We review every report and update the page.
Report an Error« Previous: Forestry and Agroforestry | Next: Soils and Soil Fertility »
Back to: Agriculture Optional PYQs – Topic-wise
Last updated: 30 October 2026