Late blight of potato is caused by

Options

A. Albugo candida
B. Phytophthora infestans
C. Alternaria solani
D. Ustilago tritici

Answer

To solve the question "Late blight of potato is caused by," we will analyze the options provided and identify the correct organism responsible for this disease.

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for the causative agent of late blight in potatoes. Late blight is a significant disease affecting potato crops.

2. **Analyze the Options**:
- **a. Albugo candida**: This organism is a fungus known to cause diseases in plants, particularly wheat rust. It is not associated with potatoes.
- **b. Phytophthora infestans**: This is a well-known pathogen that specifically causes late blight in potatoes. It is a type of water mold and is notorious for its role in the Irish Potato Famine.
- **c. Alternaria solani**: This fungus is responsible for early blight in potatoes and tomatoes, not late blight.
- **d. Ustilago triticae**: This fungus causes loose smut in cereals like barley, wheat, and rye, and is not related to potatoes.

3. **Identify the Correct Answer**: Based on the analysis, the organism that causes late blight of potato is **Phytophthora infestans**.

4. **Conclusion**: Therefore, the correct answer to the question is **b. Phytophthora infestans**.