__________causes potato blight.

Explanation

**Step-by-Step Solution:**

1. **Identify the Disease**: The question asks about the cause of potato blight, which is a disease affecting potatoes.

2. **Recognize the Causative Agent**: The disease potato blight is specifically caused by a fungus.

3. **Name the Fungus**: The fungus responsible for potato blight is known as *Phytophthora infestans*.

...