Consider the following : 1. Birds 2. Dust blowing 3. Rain 4. Wind blowing Which of the above spread plant diseases ?
- (a) 1 and 3 only
- (b) 3 and 4 only
- (c) 1, 2 and 4 only
- (d) 1, 2, 3 and 4 ✓ UPSC's answer
Why the answer is (d)
• Plant pathogens (fungi, bacteria, viruses) spread by many agents.
• Wind (4) carries fungal spores over long distances — wheat rust spores travel hundreds of kilometres; dust blowing (2) carries spores and bacteria on soil particles.
• Rain (3) splashes spores and bacteria from soil and infected leaves onto healthy plants and spreads them through run-off.
• Birds (1) carry pathogens on feathers, beaks and in droppings, and spread parasitic seeds and infected fruit.
• Hence 1, 2, 3 and 4, option (d).
Why the other options are wrong
- (a) 1 and 3 only
- Dust and wind also spread pathogens.
- (b) 3 and 4 only
- Birds and dust also spread pathogens.
- (c) 1, 2 and 4 only
- Rain also spreads pathogens by splash dispersal.
Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2018, held on 3 June 2018. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.