Please help I hope the picture is clear enough!

enter image description here

  • 1
    Where did the potatoes come from? Your garden or the shop. Did they look like this when you got them or have they turned like this over time?
    – Doug
    Jan 5, 2018 at 7:38
  • 2
    Why are you asking? Do you also want to know if you can still eat them, or how you can prevent this? Please edit that into your question.
    – user34961
    Jan 5, 2018 at 11:57
  • @JanDoggen "how to prevent" can well be offtopic here, if this is something that happens while the potatoes grow.
    – rumtscho
    Jan 5, 2018 at 17:40

1 Answer 1


Using a Google image search for 'sweet potato disease', it looks like Streptomyces ipomoea:

enter image description here

Host range and distribution:

Sweet potatoes; Ipomoea batatas; found in all major sweet potato production regions in the U.S. and Japan.

Streptomyces soil rot or pox is a widespread disease of sweet potato in North Carolina that results in a reduction in plant growth and severe yield losses. It is caused by the soilborne filamentous bacterium, Steptomyces ipomoea, and is able to persist in soil for many years in the absence of sweet potatoes. Fibrous roots and storage roots are infected in the field and symptom development varies based on the timing of root infection [...]. Disease is favored by dry soils with pH above 5.2.

If you are cultivating your own, this is what that article recommends under 'Management':

Disease development is favored at high pH. Have field soil tested regularly and select fields with pH 5.2 or lower. Develop long-range crop rotation (3-4 years) in infested fields. Treat soil with a broad spectrum soil fumigant containing chloropicrin 2-4 weeks prior to planting.

  • 2
    What about edibility? From a cook's (not gardener's) perspective, is ist a cosmetic issue or should they be discarded?
    – Stephie
    Jan 5, 2018 at 14:35
  • @Stephie I did not continue the search since the OP is unclear about the reason for the question
    – user34961
    Jan 5, 2018 at 16:26

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