Which is linked to discovery of Bordeaux mixture as fungicide ?

Options

A. Black rust of wheat
B. Bacterial leaf blight of rice
C. Downy mildew of grapes
D. Loose smut of wheat

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the discovery of Bordeaux mixture as a fungicide. We need to identify which disease it was primarily linked to.

2. **Analyzing the Options**: The options provided are:
- A) Black rust of wheat
- B) Bacterial leaf blight of rice
- C) Downy mildew of grapes
- D) Loose smut of wheat

3. **Eliminating Irrelevant Options**:
- **Option B** (Bacterial leaf blight of rice) can be eliminated because it is a bacterial disease, and Bordeaux mixture is a fungicide, which means it is used to combat fungal infections.

4. **Researching Bordeaux Mixture**:
- The Bordeaux mixture is composed of copper sulfate and calcium hydroxide dissolved in water. It was discovered in 1882 in France.

5. **Identifying the Target Disease**:
- The Bordeaux mixture was specifically used to control downy mildew, which affects grapevines. The causal agent of this disease is the fungus Plasmopara viticola.

6. **Confirming the Correct Option**:
- Since the Bordeaux mixture was discovered to combat downy mildew of grapes, **Option C** (Downy mildew of grapes) is the correct answer.

7. **Reviewing Other Options**:
- **Option A** (Black rust of wheat) is treated with a different fungicide (diethane).
- **Option D** (Loose smut of wheat) is also treated with a different systemic fungicide (D735).

8. **Final Conclusion**: Thus, the correct answer is **Option C: Downy mildew of grapes**.

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