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Ministry of Agriculture, Food and Rural Affairs

fusarium dry rot

Seed piece destroyed by Fusarium A wet rot caused by Fusarium Infected seed pieces Older lesions Internal rotted tissue Internal tuber tissue destroyed by Fusarium
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Beginner

Scientific Name
Fusarium spp

Identification
Rotted tissue is brown or grey to black, dry and crumbly. Cavities lined with yellow, pink white or blue mold develop in the rotted tissue. Older lesions are sunken and shriveled with concentric wrinkles. Cracks often form in infected areas.

Some Fusarium species cause a wet rot. The affected tissue has a jelly-like consistency.

Often Confused With
Phoma rot
Early blight tuber infection

Period of Activity
It is a seed and soil borne disease. Thus, the disease has the potential to be a problem in storage and in the field.

Scouting Notes

  • Infected seed should be graded out before seed cutting operations
  • Scouting should start at crop emergence. Poor crop emergence should be monitored to determine whether Fusarium caused the problem.
  • Check the seed in places where there is poor emergence.

Storages should be monitored closely to determine dry rot incidence.

Thresholds
No thresholds are established.

Advanced

Scientific Name
Fusarium spp

Identification
Rotted tissue is brown or grey to black, dry and crumbly. Cavities lined with yellow, pink white or blue mold develop in the rotted tissue. Older lesions are sunken and shriveled with concentric wrinkles. Cracks often form in infected areas.

Some Fusarium species cause a wet rot. The affected tissue has a jelly-like consistency.

Often Confused With
Phoma rot
Early blight tuber infection

Biology
Fusarium is the most common fungus responsible for seed piece decay and dry rot. Several species of Fusarium are present in most soils where potatoes are grown but infected seed tubers are the most important sources of inoculum. Planting infected seed results in poor stands.

Fusarium penetrates tubers through wounds or bruises that result from rough handling during harvest, transit or storage. If potatoes are infected at harvest, symptoms are noticeable in storage about a month later.

Soft rot bacteria often invade tubers infected with Fusarium, causing the seed to rot very quickly.

Period of Activity
It is a seed and soil borne disease. Thus, the disease has the potential to be a problem in storage and in the field.

Scouting Notes

  • Infected seed should be graded out before seed cutting operations
  • Scouting should start at crop emergence. Poor crop emergence should be monitored to determine whether Fusarium caused the problem.
  • Check the seed in places where there is poor emergence.

Storages should be monitored closely to determine dry rot incidence.

Thresholds
No thresholds are established.

Management Notes
Management of Fusarium seed piece decay and dry rot requires an integrated program of cultural and chemical practices which include the following strategies.

  • Plant certified seed free of Fusarium. Growers should grade out the seed very carefully to avoid planting Fusarium infected seed.
  • Use a registered seed treatment
  • Disinfect seed cutting equipment regularly
  • Harvest the crop when the skin is set.
  • Minimize mechanical injury and bruising at harvest to reduce Fusarium dry rot incidence in storage.
  • Do not dump infested cull tubers on future potato fields as they are sources of Fusarium inoculum.