Identify the incorrect pair.

Options

A. Puccinia - Causative organism of wheat rust.
B. Aspergillus - Production of citric acid.
C. Ustilago - it is also known as rust fungi.
D. Neurospora - Extensively used in genetics.

Answer

To solve the question of identifying the incorrect pair, we will analyze each of the given pairs one by one.

### Step-by-Step Solution:

1. **Identify the first pair: Paxenia - Causative organism of wheat rust.**
- Paxenia is indeed a genus of fungi that belongs to the class Basidiomycetes and is known to cause wheat rust.
- **Conclusion:** This pair is correct.

2. **Identify the second pair: Aspergillus - Used in the production of citric acid.**
- Aspergillus is a genus of fungi that falls under the class Ascomycetes and is widely used in the industrial production of citric acid.
- **Conclusion:** This pair is correct.

3. **Identify the third pair: Neurospora - Used mainly in genetics.**
- Neurospora is also a member of the Ascomycetes class and is extensively used in genetic research and biochemical studies.
- **Conclusion:** This pair is correct.

4. **Identify the fourth pair: Asterligo - Known as rust fungi.**
- Asterligo is incorrectly paired here. The correct term for rust fungi is Puccinia, while Asterligo is actually known as a smut fungus, which is different from rust fungi.
- **Conclusion:** This pair is incorrect.

### Final Answer:
The incorrect pair is **Asterligo - Known as rust fungi.**

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