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Post Harvest Diseases:: Vegetables:: Carrot

Bacterial soft rot: Erwinia carotovora sub sp. caotovora
Symptom:
  • Cells  become water soaked, middle lamella is destroyed and the cells collapse 
  • Soft, watery or slimy consistency 
  • Rotted tissues – grey to brown, accompanied by foul odour
  • In the field, tops of rotted carrots turn yellow and wilt as roots break down
 
  Soft watery carrot Rotted tissue Cross section of internal tissue

Identification of pathogen:

  • Bacteria is gram –ve, motile with large peritrichous flagella

Mode of spread and survival:

  • Soil - source of primary inoculum
  • Survive in decaying refuse and enter the root principally through cultivation wounds, harvest bruises, freezing injury, and insect openings
  • Flies – Hylemus cillicrura, H. brassicae – carry the bacteria in their intestinal tracts
Management:
  • Careful handling at harvest - minimizes bruising of carrot roots
  • Washing - dipping in a solution of sodium hypochlorite (5.25%)
  • Storage condition - temp- just above freezing(0ºC), RH 90 %
  • Crop rotation - alfalfa, beans, beets, corn
Source of Images:
http://mtvernon.wsu.edu/path_team/DiseaseGallery/carrot-bacterial-soft-rot-5.htm

http://www.infonet-biovision.org/res/res/files/2122.280x185.clip.jpeg
http://phytopath.ca/wp-content/uploads/2015/03/DPVCC-colour-plates-chapter-6-carrot.pdf

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