Which one is the wrong pairing for the disease and its causal organism

Options

A. Black rust of wheat - Puccinia graminis
B. Loose smut of wheat - Ustilago nuda
C. Root-knot of vegetables - Meloidogyne
D. Late blight of potato - Alternaria solani

Answer

To determine which pairing of a disease and its causal organism is incorrect, we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Identify the first option: Black rust of wheat**
- Causal organism: *Puccinia graminis*
- Analysis: This pairing is correct. Black rust, also known as stem rust, is indeed caused by the fungus *Puccinia graminis*.

2. **Identify the second option: Loose smut of wheat**
- Causal organism: *Ustilago nuda*
- Analysis: This pairing is also correct. Loose smut of wheat is caused by the fungus *Ustilago nuda*.

3. **Identify the third option: Root knot of vegetables**
- Causal organism: *Meloidogyne*
- Analysis: This pairing is correct as well. Root knot nematodes, which belong to the genus *Meloidogyne*, are known to cause root knots in various vegetables.

4. **Identify the fourth option: Late blight of potato**
- Causal organism: *Alternaria solani*
- Analysis: This pairing is incorrect. Late blight of potato is caused by *Phytophthora infestans*, while *Alternaria solani* is responsible for early blight of potatoes and tomatoes.

### Conclusion:
The wrong pairing is the fourth option: Late blight of potato caused by *Alternaria solani*.

### Final Answer:
The wrong pairing is: Late blight of potato - *Alternaria solani*.

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