Clavibacter michiganensis pv

Bacterial Disease

Clavibacter michiganensis pv

Bacterial Disease

Clavibacter michiganensis pv

Bacterial Disease

Clavibacter michiganensis pv

Bacterial Disease

Tomato Bacterial Canker: Symptoms, Spread, and Survival

Tomato bacterial canker, caused by Clavibacter michiganensis, is a serious disease affecting both greenhouse and field-grown tomatoes. It primarily spreads through contaminated seeds and handling practices.

Symptoms

• Early Symptoms:

  • Unilateral wilting or withering of leaflets on one side of the leaf.
  • Desiccation of leaflet edges, sometimes overlapping with plant wilt.
  • Stunted growth and rapid withering in young infected seedlings.

• Leaf and Stem Symptoms:

  • Small, whitish or tan pustules on leaf veins, petioles, and peduncles.
  • Brown streaks on stems and petioles due to vascular discoloration.
  • Cutting stems reveals creamy-white, yellow, or reddish-brown vascular tissue and cavities in the pith.
  • In severe cases, brown streaks darken and split open, forming cankers.
  • Marginal leaf necrosis in late-season infections.

• Fruit Symptoms:

  • Bird’s eye-spot lesions – raised white spots with necrotic centers.
  • Small, prematurely falling fruits with uneven ripening.
  • External marbling and internal vascular bleaching.

Disease Spread

• Primary Source: Seedborne pathogen (C. michiganensis).
• Secondary Spread:
  • Handling operations (clipping, packaging, tying, staking).
  • Deleafing, suckering, and tying in greenhouses.
  • Water splashing from rain, overhead irrigation, or chemical sprays.
• Vascular infection leads to stunted growth, wilting, and early plant loss.

Survival and Persistence

• Pathogen populations decline rapidly in decomposing crop residue.
• Survives in unbroken crop debris on the soil surface, initiating infections in new plantings.
• Persists on volunteer tomato seedlings and alternative host species, acting as reservoirs of infection.

Conclusion

Bacterial canker is a destructive disease that spreads easily through contaminated seeds and handling practices. Proper seed sanitation, crop residue management, and careful handling are essential to minimize its impact.