Question

In plants, mosaic formation, leaf rolling and curling, yellowing of plant parts, vein clearing, dwarfing and stunted growth, necrosis etc. are the symptoms of

• A. Bacterial diseases
• B. Mycoplasmal diseases
• C. Viral diseases
• D. Fungal diseases

Answer 1

The correct option is C

Viral diseases

The correct option is C.

Explanation of the correct option:

1. Mosaic formation, leaf rolling and curling, yellowing of plant parts, vein clearing, dwarfing and stunted growth, necrosis, etc. in plants are the symptoms of ‘viral diseases’.
2. Plant diseases cause major economic loss. They are a threat to sustainable agriculture,
3. International trade, climate change, and the ability of viruses for rapid evolution lead to an increase in viral disease in plants.
4. Immunization and cross-hybridization for disease resistance can prevent viral diseases.

Explanation of the incorrect options:

Option A:

1. The major bacterial disease in plants is vascular wilt, soft rot, necrosis, and tumours.
2. Bacterial pathogens enter plants through wounds.
3. Wounds may be the result of adverse weather conditions, human actions, insects or nematodes, or natural openings such as stomata, lenticels, etc.

Option B:

1. Mycoplasma is transmitted by insects. It can have symptoms such as phyllody.
2. Phyllody is when flower stalks grow large and flattened like leaves. Mycoplasma unlike bacteria has no cell wall.

Option D:

1. Fungal diseases can affect all parts of plants.
2. Common fungal diseases include common root rot, crown rot, stem rust, leaf blight, and black point.

Final answer: Mosaic formation, leaf rolling and curling, yellowing of plant parts, vein clearing, dwarfing and stunted growth, necrosis, etc. are the symptoms of viral diseases.