WSU Extension

Hortsense

Potato
 
Disease
Bacterial soft rot and blackleg 
Late blight 
Potato leafroll mosaic (Leafroll) 
Powdery scab 
Rhizoctonia canker (Black scurf) 
Scab (Common) 
Verticillium wilt (Potato early dying) 
Insect
Colorado potato beetle 
Potato flea beetles 
Slugs 
Wireworms 



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Caption: Potato common scab
Photo by: R.S. Byther
  
Potato : Scab (Common)
(revision date: 6/3/2014)


Biology
Common scab is characterized by the development of brownish, corky or scabby spots on the surface of the tubers. The spots may be up to 1/4" or more in diameter and slightly raised, or may develop into pitted, corky areas. Severe infections may deform tubers, but the damage is typically aesthetic. Common scab occurs more frequently in slightly alkaline soils, or soils which have been amended with fresh manure or wood ashes. The disease is less frequent on potatoes planted in moist soils. Smooth-skinned varieties are more susceptible than russet varieties. Beets are also susceptible.
Management Options


Non-Chemical Management
  • Plant tolerant varieties such as 'Nooksack', 'Norgold', 'Russet Burbank', and 'Targhee'. 'Red Norland' is a red potato that is moderately resistant to common scab.
  • Plant disease-free seed pieces in disease-free soil.
  • Do not use fresh manure or wood ashes on potato or beet crops. Rotate to non-susceptible crops before using these materials.
  • Do not lime soil prior to planting potatoes.
  • Keep soil moist during early tuber formation (do not overwater).
  • Peel off scabby skins before use.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images

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Caption: Potato common scab
Photo by: R.S. Byther