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Potato Mop Top Virus (PMTV) – Quick Facts

What is PMTV?
  • PMTV causes tuber necrosis in sensitive cultivars.
  • PMTV rarely causes foliar symptoms.
  • PMTV is transmitted by the organism that causes powdery scab.
  • PMTV has a fairly narrow host range including potato and a few weed species.
  • PMTV is long-lived in the soil within powdery scab spore balls.
  • Powdery scab produces spore balls on only a few species.
  • PMTV and powdery scab are introduced to farms on infested potatoes and contaminated equipment.
  • Control of PMTV requires managing both the virus and powdery scab vector.
What can I do about it?

For additional details please see Potato Mop Top Virus Management.

Avoid introduction of powdery scab and PMTV onto your farm.

  • Don’t plant symptomatic seed. Inspect seed for lesions and necrosis.
  • Don’t allow contaminated equipment onto your farm.
  • Avoid manure and compost that may contain spore balls of powdery scab.
  • Do not plant other potentially infected crop hosts such as sugar beet, oat and tomato.
  • Test potting mix for powdery scab before using it for minituber production and before planting
    minitubers on your farm.

Manage inoculum levels on your farm. Avoid spreading PMTV and powdery scab from infested
fields to clean fields.

  • Monitor the powdery scab levels in your fields by testing soil samples.
  • Practice strict on-farm sanitation protocols.
  • Avoid moving contaminated soil, plant debris or manure to clean fields.
  • Avoid and destroy alternative hosts.
  • Manage soil moisture especially during tuber initiation and early bulking phases.
  • Manage powdery scab with fluazinam as part of an integrated management plan.
  • Use sorghum-sudan grass as green manure.

Plant potatoes strategically to reduce risk and the spread of disease.

  • Do not plant seed potatoes in infested fields.
  • Avoid planting ware potatoes in infested fields.
  • Do not plant ware potatoes in highly infested fields.
  • Be aware that planting any crop in PMTV infested fields will increase your risk of spreading the pathogen on your farm.

Use cultivars insensitive to PMTV induced tuber necrosis and resistant to powdery scab in infested fields to reduce loss.

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