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Potato

Tuber Damage Symptoms—Harvest

On this page
  • Fusarium dry rot
  • Bacterial soft rot
  • Late blight
  • Pink rot
  • Leak
  • Early blight
  • Black dot
  • Silver scruf
  • Rhizoctonia
  • Common scab
  • Powdery scab
  • Potato tuberworm
  • Flea beetles
  • Wireworms
  • Root knot nematode
  • Leafroll net necrosis
  • Thumbnail cracks
  • Shatter bruise
  • Blackspot bruise

Names link to information on identification and management.

Click on photos to enlarge

Fusarium dry rot
Fusarium dry rot

Identification tip: Dry, wrinkled lesions on the tuber surface; white or pink mold often develops; underlying rotted tissue dry, unless invaded by bacteria.

Bacterial soft rot
Bacterial soft rot
Identification tip: Lesions with distinct, dark margins; rotted tissue tan or cream colored and soft.

Late blight
Late blight
Identification tip: Brownish purple areas with black margins on tuber surface; underlying rotted tissue coppery brown, granular, lacking distinct margins.

Pink rot
Pink rot
Identification tip: Rotted tissue with distinct, dark margins; decayed tissue firm, turns pink then black when exposed to air.

Leak
Leak
Identification tip: Rotted areas with distinct, dark margins; decayed tissue spongy, wet, may turn pink; eventually turns dark gray.

Early blight
Early blight
Identification tip: Tuber lesions dark brown and sunken; underlying tissue brown, corky, and dry.

Black dot
Black dot
Identification tip: Gray patches on the tuber surface similar to silver scurf; tiny black dots within lesions distinguish black dot from silver scurf.

Silver scurf
Silver scurf
Identification tip: Light brown or grayish, leathery, shiny patches on tuber surface; lesions may turn dark and sooty.

Rhizoctonia stem and stolon canker
Rhizoctonia (black scurf)
Identification tip: Hard, irregularly shaped black flecks in the surface that do not penetrate the skin and are not easily rubbed off.

Common scab
Common scab
Identification tip: Irregularly shaped lesions in patches with dark brown, corky tissue; may appear raised above the tuber surface or as sunken pits.

Powdery scab
Powdery scab
Identification tip: Dark, pimple- or wart-like pustules about 1/8 to 1/4 inch in diameter.

Potato tuberworm
Potato tuberworm
Identification tip: Holes in tuber surface and tunnels in tuber flesh filled with dark excrement.

Flee beetles
Flea beetles
Identification tip: Pimples on tuber surface; small, brown tunnels penetrating up to ¼ inch into tuber flesh.

Wireworms
Wireworms
Identification tip: Shallow to deep holes in tubers lined with skin; excrement not present.

Root knot nematodes
Root knot nematodes
Identification tip: Irregular bumps or warts on tuber surface sometimes present; brown spots in tuber flesh, mostly in the outer 1/4 inch.

Leafroll net necrosis
Leafroll (net necrosis)
Identification tip: Brown spots or streaks in tuber flesh, usually concentrated at the stem end.
Thumbnail cracks
Thumbnail cracks
Identification tip: Shallow, curved cracks in the tuber surface caused by rough handling when tubers are cold and turgid.
Shatter bruise
Shatter bruise
Identification tip: Splits in tuber skin from cold tubers bumping against hard surfaces.

Blackspot bruise
Blackspot bruise
Identification tip: Small to large, dark discolored areas underneath tuber skin; damage usually not visible unless potato peeled.

 

 


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