Consider the following: 1. Birds 2. Dust blowing 3. Rain 4. Wind blowing Which of the above spread plant diseases ?
- A1 and 3 only
- B3 and 4 only
- C1, 2 and 4 only
- D1, 2, 3 and 4Correct
Explanation
All four agents spread plant diseases.
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Birds carry pathogens (fungal spores, bacteria, viruses) and insect vectors on their bodies, beaks, and through droppings between plants.
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Dust blowing carries fungal spores, bacterial cells, and small insect eggs over considerable distances; settling dust can initiate new infections.
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Rain disperses plant pathogens via rain-splash from leaf to leaf and plant to plant, and heavy rain can also wash inoculum into soil and onto neighbouring plants, helping spread fungal and bacterial diseases.
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Wind blowing is a major agent for airborne pathogens — fungal spores, virus-carrying pollen, and small insect vectors are dispersed over long distances.
Since all four are recognised modes by which plant diseases spread, the answer is D (1, 2, 3 and 4).
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