Early symptoms include yellow spots appearing on the leaves.
Later these symptoms grow inside the leaves and the stem.
These symptoms is what that differentiate black rot from wilt disease
As the disease is spread the cabbage leaves turn brown.
For effective control of this disease use Streptocycline @ 20 gram/acre Validamycin 3% SL@ 300 ml/acre or Copper hydroxide 77% WP @ 750 gram/acre or Kasugamycin 5% + Copper oxychloride 45% WP@ 400 gram/acre
As a biological treatment, spray Pseudomonas fluorescens@ 250 gram/acre.