Onion root rot

Onion Pythium root rot: Pythium aphanidermatumP. debaryanum and P. ultimum

  • This disease causes seed rotting, pre-emergence damping off. The disease appears in circular patches in the field here and there.
  • All the affected plants get killed. if the disease occurs prior to seed germination, it causes gappiness.
  • The seeds or seed materials are killed before their establishment.
  • The disease also occurs after the establishment of the crop i.e after 15 to 30 days of sowing or planting. This stage is called post-emergence damping off.
  • If the disease occurs very late, it causes stunting of the plant and rotting of the roots.
Identification of pathogen:
  • The disease is caused by complex of Pythium aphanidermatumP. debaryanum and P. ultimum
  • Seed treatment with Thiram or Captan @ 4g/kg. The bulbs may be dipped in Thiram solution 0.25%.
  • After sprouting, the root region of the plants along the rows should be given a soil drenching with Copper oxychloride 0.25%.



  • TamilNadu Agritech Portal
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