What is the black stuff on old cauliflower?

Black spots on cauliflower are likely caused by a fungal disease called black rot, which is caused by the fungus *Xanthomonas campestris pv. campestris*. The pathogen can survive in the soil for several years and can be spread by wind, water, or insects.

Symptoms of black rot include:

- Small, black spots on the leaves, stems, and heads of cauliflower

- The spots may enlarge and merge together, forming large, black areas

- The affected tissue may become soft and rot

- The entire head of cauliflower may eventually rot and fall off the plant

Prevention and control of black rot includes:

- Using disease-free seed

- Avoiding planting cauliflower in fields where black rot has occurred in the past

- Rotating crops to avoid building up the inoculum level in the soil

- Applying fungicides as needed

- Removing and destroying infected plants

If you see black spots on your cauliflower, it's important to take action to prevent the disease from spreading.