Canker: Xanthomonas campestris pv citri

Symptoms

• Acid lime, lemon and grapefruit are affected. Rare on sweet oranges and mandarins.
• Affects leaf, twig and fruits. In canker, leaves are not distorted.
• Lesions are typically circular with yellow halo; appear on both sides of leaf, severe in acid lime (difference from scab) When lesions are produced on twigs, they are girdled and die.
• On fruits, canker lesions reduce market value.

Management

• Streptomycin sulphate 500-1000 ppm; or Phytomycin 2500 ppm or Copper oxychloride 0.2% at fortnight intervals.
• Control leaf miner when young flush is produced.
• Prune badly infected twigs before the onset of monsoon