A parasitic nematode that causes a great reduction in yield of tobacco crop is

Options

A. Claviceps purpurea
B. Puccinia graminis
C. Meloidegyne incognitia
D. Mycosphaerella berkeylli

Answer

To solve the question about which parasitic nematode causes a significant reduction in the yield of tobacco crops, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for a specific parasitic nematode that impacts tobacco crops.

2. **Analyze the Options**: The options provided are:
- A) Claviceps purpurea
- B) Puccinia graminis
- C) Meloidogyne incognita
- D) Mycosphaerella berkeleyi

3. **Evaluate Each Option**:
- **Claviceps purpurea**: This is a fungus that primarily affects rye crops, not tobacco.
- **Puccinia graminis**: This is a fungal pathogen that causes rust in various plants, but it does not specifically target tobacco.
- **Meloidogyne incognita**: This is a well-known plant parasite commonly referred to as the root-knot nematode. It specifically affects the roots of various plants, including tobacco, leading to a reduction in yield.
- **Mycosphaerella berkeleyi**: This fungus affects peanuts and causes late leaf spot, not tobacco.

4. **Identify the Correct Answer**: Based on the evaluations, the only option that directly affects tobacco crops is **Meloidogyne incognita**.

5. **Conclude**: Therefore, the correct answer to the question is option C, **Meloidogyne incognita**.

### Final Answer:
**C) Meloidogyne incognita**

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