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Damping Off

A fatal disease of seedlings where young plants collapse and die at soil level shortly after germination. Caused by fungal pathogens in the growing medium.

Symptoms

  • check_circleSeedlings collapsing suddenly at soil level
  • check_circleThin, water-soaked constriction at the base of the stem
  • check_circleSeedlings appearing healthy one day and dead the next
  • check_circlePatches of seedlings dying in clusters
  • check_circleWhite mould visible on the soil surface

Causes

  • arrow_rightOverwatering creating conditions for fungal growth
  • arrow_rightPoor drainage in seed trays
  • arrow_rightUsing unsterilised compost or garden soil
  • arrow_rightSowing too densely
  • arrow_rightLow temperatures combined with wet conditions

How to Diagnose

The collapse at soil level with a shrunken stem base is characteristic. It spreads from seedling to seedling and cannot be reversed once established.

Treatment

There is no cure — remove and discard affected seedlings and compost to prevent spread. Water remaining seedlings with a copper fungicide solution (Cheshunt compound). Improve air circulation around remaining seedlings.

Prevention

Use fresh, sterile compost for seeds. Sow thinly and prick out early to improve spacing. Water from below rather than overhead. Ensure good ventilation. Do not overwater — allow the surface to dry slightly between waterings.