Damping Off

Damping off describes the usually sudden destruction of newly germinated seeds or seedlings. Young plants can be attacked at all stages, before germination (pre-emergence damping off) and after seedlings grow from the soil (post-emergence damping off). All types of plants including turf, trees, vegetables, and flowering plant seedlings can be affected.

Symptoms caused by chemical toxicity, extremes in soil moisture and temperature, and poor seed health can mimic damping off.

Several organisms can cause damping off. Pythium, Phytophthora, Fusarium, and Rhizoctonia are four common culprits. These fungi can be found in most soils. However, appropriate environmental conditions are essential for disease development.

Cool, wet soil conditions are favorable for infection by damping off fungi. Plants grow slowly at cool temperatures, making them vulnerable to fungal attack. Also, many fungi prefer moist environments.

The following management strategies can help:

  • Use planting media free of disease organisms.
  • Avoid setting flats or pots on the ground.
  • Use good quality seed.
  • Plant seeds at densities that will allow air circulation and light penetration; and reduce competition for nutrients.
  • Keep the temperature at a level that will promote plant growth.
  • Avoid excess moisture.
  • Fungicides and treated seeds (for some plants) are available.

This article originally appeared in the February 8, 2002 issue, p. 13.

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