Consider the following:BirdsDust blowingRainWind blowingWhich of the above spread plant diseases?

Q: What is UPSC Prelims?

UPSC Prelims is a competitive examination conducted in India. This question is from the 2018 UPSC Prelims Science & Technology paper.

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To prepare for UPSC Prelims Science & Technology, practice previous year questions (PYQs), understand concepts thoroughly, and solve mock tests regularly. This 2018 question covers Biology – Cell, Genetics, Human Body & Diseases topic.

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This UPSC Prelims 2018 Science & Technology question has a medium difficulty level and is marked as an important question.

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Question

Consider the following:BirdsDust blowingRainWind blowingWhich of the above spread plant diseases?

Accepted Answer

Correct Answer: D — 1, 2, 3 and 4Step-by-step Solution:Plant diseases are spread through various vectors and environmental agents. All four listed agents are documented disease vectors or carriers:Item 1 — Birds: Correct. Birds spread plant diseases in several ways: they can carry fungal spores, bacterial pathogens, and viruses on their bodies, feet, or through droppings; birds feeding on infected plants can transfer pathogens to healthy plants; some plant viruses are transmitted through aphids and insects that birds carry or disturb. Birds are known vectors of several plant pathogens. ✓Item 2 — Dust blowing: Correct. Wind-blown dust particles can carry fungal spores, bacterial cells, and nematode eggs over short and long distances. Dust storms have been documented to spread plant pathogens across large geographical areas. Soil-borne pathogens can be lifted and transported by wind-blown dust. ✓Item 3 — Rain: Correct. Rain is one of the most important dissemination agents for plant pathogens: rain splash spreads spores from infected to healthy leaves; rain water washes fungal spores from one plant to another; rain creates humid conditions that favour pathogen germination and infection; rain drops can dislodge and carry bacterial exudates containing pathogens. Many foliar diseases (like blast in rice, late blight in potato) spread rapidly during rainy periods. ✓Item 4 — Wind blowing: Correct. Wind is perhaps the most important long-distance dissemination agent for plant diseases. Fungal spores (conidia, ascospores, basidiospores) are specifically adapted for wind dispersal — they are light, small, and produced in enormous quantities. Wheat rust (Puccinia spp.) is a classic example of a wind-dispersed pathogen that can spread thousands of kilometres. ✓Why other options are incorrect:Options A, B, and C each exclude at least one valid disease-spreading agent. All four listed agents genuinely contribute to plant disease dissemination.Key Concept: Plant disease dissemination mechanisms: (1) Air — wind, dust, aerosols (fungi, bacteria); (2) Water — rain splash, irrigation water, flood (fungi, bacteria, nematodes); (3) Soil — tillage, boots, implements (soilborne pathogens); (4) Animals — birds, insects (aphids, whiteflies, thrips as virus vectors), nematodes; (5) Human activities — contaminated seeds, transplants, tools, movement of plant material. Plant pathology is tested in UPSC for both science/technology and agriculture sections.

Consider the following:BirdsDust blowingRainWind blowingWhich of the above spread plant diseases?

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Consider the following:BirdsDust blowingRainWind blowingWhich of the above spread plant diseases?

Master UPSC Prelims with Our Test Series

More Questions from Biology – Cell, Genetics, Human Body & Diseases

Frequently Asked Questions