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Damping Off

Protecting Seedlings from Damping Off Disease

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Damping Off Disease

Damping Off affects young seedlings, shortly after germination.

Photo: © Marie Iannotti

What is Damping Off?

Damping off is a term used for seedling death by any of a handful of fungal diseases, including several root rots (Pythium, Phytophthora) and molds (Sclerotinia or white mold, Botrytis or gray mold).

Symptoms of Damping Off

Damping off can affect seedlings under and above ground. Seedlings may start to grow and whither, break off or collapse while they still have their cotyledons. You may see some gradual discoloring or it may happen very suddenly. Often it appears the seedling has been pinched off at the soil line.

Seedlings with root rot can appear to be wilting, even when kept watered. Even poor germination may be attributable to damping off.

 

How to Prevent Damping Off

  1. Use a sterile potting mix, rather than soil from your garden. Outdoor soil can harbor fungus spores.

  2. Start with clean pots. If reusing pots, sterilize in 1 part beach to 10 parts water.

  3. Plant your seeds at the proper depth. Don’t bury the plant’s crown.

  4. Don’t crowd your seedlings. Be sure to leave room between them for air circulation.

  5. Water seedlings from the bottom.

  6. Top potting mix with a thin coating of sand or gravel, to keep the surface relatively dry.

  7. Don’t over water your seedlings or leave them sitting in water.
  8. If possible, create a breeze by placing a small fan nearby and tuning it on periodically each day.

  9. Give your seedlings plenty of heat and light, so they germinate and grow quickly. Damping off only affects seedlings.

  10. Remove any affected plants or trays of plants immediately.

Tips for Protecting Your Seedlings from Damping Off

  • Sterilize Your Own Soil

    Sterilize small quantities of soil by heating it. Doing this in the oven gives off an unpleasant odor, but microwaves don’t seem to produce the same problem. Place dampened potting mix in a microwave safe container and cover loosely. Microwave on high for 8 - 10 minutes, until you see condensation under the lid. Close the lid and let the potting mix cool on its own. .

  • Make your own Organic Fungicide

    • A strong brew of chamomile or cinnamon tea. Use it to water and/or mist your seedlings.

    • A splash (1 T.) of 3% solution of hydrogen peroxide/ qt. water as a seedling mist.

    • A dusting of cinnamon on the soil surface.

       

A strong, commercial fungicide is a last resort for controlling damping off and will probably applied too late to be effective. Sometimes you have to be prepared to start over, taking precautions to avoid damping off the next time.

Sources:

University of Connecticut IPM
University of Arizona Cooperative Extension

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