What is the name of rust fungus ?

Explanation

### Step-by-Step Solution:

1. **Understanding Rust Fungus**: Rust fungi are a group of fungal pathogens that primarily affect plants, causing diseases characterized by rust-colored spots on leaves and stems.

2. **Classification of Rust Fungi**: Rust fungi belong to a specific order in the fungal classification system. The order is known as "Pucciniales."

3. **Historical Context**: The order Pucciniales was previously referred to as "Erysiphales." This highlights the evolution of scientific classification over time.

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