Bacterial Canker

Bacterial canker on apple treeBacterial canker is often confused with bacterial speck and bacterial spot, which cause very similar symptoms. Bacterial canker invades the plant's vascular system, causing browning of internal plant tissues. Fruits may also turn brown inside.

The bacterium thrives in warm, wet weather and is spread by rain and wind; it infects plants through wounds on the leaves and stem and is then transmitted throughout the plant. The bacterium overwinters on weeds in the nightshade family, volunteer tomato plants, and plant debris (including seeds). Plants infected with bacterial canker cannot be saved.

Prevention and Control

  • Grow only certified, disease-free seeds and plants.
  • A 5-year rotation for tomato plantings is ideal.
  • Keep plants healthy and avoid injury to plant tissues.
  • Mulch the soil around plants to prevent splashing of soil onto foliage and fruits.
  • Avoid overhead watering in favor of drip irrigation or soaker hoses, which keep foliage dry.
  • Uproot and destroy infected plants as soon as you spot them.

Last updated: 03/14/2024