Correct Option
The correct option is
All three pairs
Explanation
Plant diseases are caused by a variety of microorganisms, including bacteria, fungi, and viruses. These pathogens are classified based on their biological nature and mode of transmission, significantly impacting agricultural productivity.
Analysis of Pairs:
- Pair 1 is Correct: Citrus canker is a bacterial disease caused by Xanthomonas axonopodis (formerly Xanthomonas citri). It affects citrus plants, causing lesions on leaves, stems, and fruits, and is commonly transmitted through air and water.
- Pair 2 is Correct: Rust of wheat is a fungal disease caused by species of the genus Puccinia (e.g., Puccinia graminis). It manifests as rust-colored pustules on the plant parts and is transmitted through air or infected seeds.
- Pair 3 is Correct: Yellow vein mosaic of bhindi (Okra) is a viral disease caused by the Yellow Vein Mosaic Virus. It is transmitted by an insect vector, specifically the whitefly (Bemisia tabaci), and results in the yellowing of leaf veins.
Key Takeaway:
Major plant diseases and their causative agents include Citrus Canker (Bacteria), Wheat Rust (Fungi), and Yellow Vein Mosaic (Virus).