Pacific Pests, Pathogens & Weeds - Mini Fact Sheet Edition

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Damping-off (047)

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Photo 1. Onion seedlings attacked before emerging through the soil and afterwards. An example of pre- and post-damping-off. (Germination of the seed was high!)

Photo 2. Cabbage seedlings have been attacked at the junction of stem and soil, a case of post-emergence damping-off.

Photo 3. Damping-off in Chinese cabbage. When plants are sown thickly like this it encourages spread of the disease.

Summary

• Worldwide distribution. On many kinds of fruit and vegetable seedlings in the nursery, with beans, cabbage, carrot, lettuce, onion, and tomato especially susceptible. Important diseases.
• Mostly caused by soil fungi and water moulds, oomycetes. Damping-off is of two kinds: (i) death before emergence; and (ii) death after emergence.
• Spread in water splash, on tools, and in potting mixes.
• Cultural control: nursery hygiene: pasteurise soil or soilless mixes, monitor; if outbreaks in seed beds, move to different sites; do not use pond or stream water; do not over-water; ensure boxes have good drainage; avoid soil splash: raise seed boxes above ground (>1 m) to avoid rain splash.
• Chemical control: seed – captan, thiram, or mancozeb. Treat seed boxes with 1% bleach for 5 min, then rinse.

Common Name

Damping-off

Scientific Name

Commonly, Pythium and Rhizoctonia are involved, but Fusarium and Phytophthora may also cause similar diseases. Note, Pythium and Phytophthora are not fungi but water moulds or oomycetes, related to algae.

This mini fact sheet is a part of the app Pacific Pests, Pathogens & Weeds

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