The causative organism of downy mildew in cereals is

Options

A. Pythium debaryanum
B. Peronospora parasitica
C. Sclerospora glaminicola
D. Saprolegnia

Answer

To determine the causative organism of downy mildew in cereals, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Downy Mildew**:
- Downy mildew is a fungal disease that affects various plants, including cereals. It is characterized by specific symptoms on the leaves.

2. **Identify Symptoms**:
- The symptoms of downy mildew include large yellow areas on the leaves, which may appear on both the upper and lower surfaces. The lower surface often becomes water-soaked, and lesions can expand rapidly, leading to significant damage to the leaf tissue.

3. **Research Causative Organisms**:
- Various organisms can cause downy mildew, and they belong to the family of Oomycetes. It is essential to identify which specific organism is responsible for downy mildew in cereals.

4. **Evaluate the Options**:
- The options provided are:
- Pythium
- Diberium
- Paranospora
- Parasitica
- Sclerospora
- Glaminigola
- Saproligenia

5. **Identify the Correct Organism**:
- After reviewing the options, it is noted that the causative organism of downy mildew in cereals is **Paranospora parasitica**. This organism belongs to the family Paranosporaceae, which is known for causing downy mildew in various plants.

6. **Conclusion**:
- Therefore, the correct answer to the question is **Paranospora parasitica**.

### Final Answer:
The causative organism of downy mildew in cereals is **Paranospora parasitica**.