Pink Rot

Symptoms often begin at the stolon end of the tuber. Damage is sometimes bordered by a dark line visible on outside of the tuber. Recently infected tissue turns pink, and then black, when exposed to air. Infections in storage may cause an ammonia-like smell.

Causal Agent:

Phytophthora erythroseptica

Biology:

Pathogen of potato and many other plants; present in many soils worldwide; tuber infection and decay is worst in warm and excessively wet soils.

Dispersal:

Infection can spread from tuber to tuber during harvest and handling. Infected seed can also spread the disease.

Fungicide Resistance:

P. erythroseptica has begun to demonstrate resistance to fungicides. Fungicides should be rotated frequently to prevent resistance.

Management:

  1. Plant in well-drained fields without a history of the disease.
  2. Avoid excessive irrigation late in the growing season, and do not plant in areas of fields expected to become excessively wet.
  3. Avoid wounding during harvest and transfer to storage.
  4. Harvest storage crops in cool weather and with cooler pulp temperatures.
  5. Sort infected tubers at harvest, and process or ship affected lots promptly.
  6. Some fungicides are active against pink rot, but take care to avoid encouraging fungicide resistance.

Further Reading:

Pacific Northwest Pest Management Handbooks