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Elsinoë potatoes (Saw.) Viega & Jensen (teleomorph)  

Sphaceloma potatoes (anamorphe)

Sweet potato scab




  • Worldwide widespread fungal disease specific to sweet potato.
  • Sometimes attributed to Sphaceloma batatas which is actually the asexual form of the fungus (anamorph).
  • Symptoms affecting young leaves and stems of the plant.


  • Susceptible botanical family(s)

The sweet potato is the only known vegetable


  • Production areas affected :
New Caledonia


  • Organs attacked
Leaves Stems



  • Symptoms :
      • Appearance of small black necrotic lesions along leaf veins and on young stems. These alterations elongate and take on a corky appearance and an often rusty color along the leaf veins. The latter show more or less a blocked development and a tense aspect.
      • Comparable lesions on petioles causing their deformation locally.
      • Corky areas on stems of a rather beige color as on the petioles.
      • In strong attacks, the leaves are curled up, the stems are erect.
  • Signs : Can't we see sporulation of the fungus?
  • Possible confusion : Little possible confusion



  • Storage : the fungus can survive on plant crop debris. Its other modes of preservation are still poorly understood.
  • Infection : After germination, the fungus penetrates plant tissues and produces corky patches.
  • Sporulation  : 
  • Dissemination : Naturally, spores produced by corky lesions are dispersed by wind and splashing rainwater. In addition, dissemination can be done by using infected cuttings
  • Favorable conditions : presence of free water on the plants (rain or dew) favoring the germination of the spores.



  • Use tolerant or resistant varieties.
  • Respect the principle of crop rotation.
  • Avoid planting near a field that has been heavily impacted.
  • Use healthy cuttings showing no symptoms of scab. The production of seed-bed cuttings improves the sanitary quality of the plant material produced.
  • Remove the leaves from the cuttings before planting in a preparation area away from the field, to limit the risk of disease development at the start of the crop.
  • Encourage aeration and sunshine of the crop (planting density and choice of plot according to its orientation).
Last change : 07/21/22
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