Which of the following diseases is caused by bacteria ?

Options

A. Tabacco mosaic
B. Black rot of crucifers
C. Red rot of sugarcane
D. Light blight of potato

Answer

To determine which of the diseases listed is caused by bacteria, we will analyze each option provided:

1. **Tobacco Mosaic**: This disease affects tobacco plants and is caused by the Tobacco Mosaic Virus (TMV). Since it is caused by a virus, this option is incorrect.

2. **Black Rot of Crucifers**: This disease affects cruciferous plants (like cabbage and broccoli) and is caused by the bacterium *Xanthomonas campestris*. Since it is caused by bacteria, this option is correct.

3. **Red Rot of Sugarcane**: This disease is caused by the fungus *Colletotrichum falcatum*. As it is caused by a fungus, this option is incorrect.

4. **Late Blight of Potato**: This disease is caused by the fungus *Phytophthora infestans*. Since it is also caused by a fungus, this option is incorrect.

After analyzing all the options, we conclude that the disease caused by bacteria is **Black Rot of Crucifers**.

### Summary of the Solution:
- **Tobacco Mosaic**: Caused by a virus (incorrect).
- **Black Rot of Crucifers**: Caused by *Xanthomonas campestris* (correct).
- **Red Rot of Sugarcane**: Caused by a fungus (incorrect).
- **Late Blight of Potato**: Caused by a fungus (incorrect).

**Correct Answer**: Black Rot of Crucifers