The rusts are serious diseases of our economic plants. The disease is caused by the fungus

Options

A. Rhizopus
B. Ustilago
C. Puccinia
D. Agaricus

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the fungus that causes rust diseases in economic plants, particularly focusing on wheat.

2. **Identifying the Group of Fungi**: Rust diseases are primarily caused by fungi belonging to the group known as Basidiomycetes.

3. **Analyzing the Options**:
- **Option 1: Rhizopus**: This is known as black bread mold (Rhizopus stolonifer). It is not associated with rust diseases, making this option incorrect.
- **Option 2: Eustelago**: Specifically, Eustelago triticae is associated with loose smut of wheat, not rust. Therefore, this option is also incorrect.
- **Option 3: Puccinia**: This genus belongs to Basidiomycetes and is responsible for causing black rust of wheat, specifically Puccinia graminis triticae. This option is correct.
- **Option 4: Agaricus**: Commonly known as mushrooms, Agaricus species are edible and do not cause rust diseases. Thus, this option is incorrect.

4. **Conclusion**: The correct answer is **Option 3: Puccinia**, specifically Puccinia graminis triticae, which is responsible for the serious rust diseases affecting wheat.

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