Damping-Off

Damping-off is a common disease that kills seedlings in the greenhouse. Damping-off can kill both germinating seeds and young seedlings. Several fungi can cause this disease, including Rhizoctonia solani, Pythium spp., Phytophthora spp., Sclerotinia spp., and Botrytis spp. Most of these fungi can also cause cuttings to rot. These fungi are found in practically all soils and pose a large threat to plant propagation. Practically all species of plants can be affected.

Symptoms. Damping-off often is seen in round patches in seeding flats. Preemergence damping-off is a term used to describe the rot of seeds, or the death of the seedlings, before they emerge from the soil. Post-emergence damping-off affects seedlings that have already emerged from the soil. These seedlings may develop a dark stem rot near the soil surface which will cause them to fall over and die as the rotted area shrivels.

 

 

 Left: Damping off in a tray of seedlings. 
D. Kerbow photo
Right: Post-emergence damping off by pythium.
They may also rot from the tips of the roots. This rot will progress up the seedling until the stem is rotted. Seedlings that survive until they are a bit older before they are infected may develop "wire-stem", a condition in which the base of the stem is partially invaded by the fungus. There is often a discolored and slightly shriveled or constricted area at or just below the soil line. Although the plant lives for a while, it is stunted and pale, and often will eventually die. Brown or white fungal growth may be seen on the surface of the potting media or on the seedlings themselves.

Prevention. The best way to control this disease is to prevent it. There are many prevention techniques, and a combination of them is most effective.

 

 

 

By Pamela S. Mercure, IPM Program Assistant, University of Connecticut, 1998
References.

Baker, R. 1985. Damping-Off in Diseases of Floral Crops, Volume 1. Chapter 1 Praeger, New York. D.L. Strider, ed.

Chase, A.R. 1995. Compendium of Ornamental Foliage Plant Diseases. APS Press, St. Paul, MN.

Daughtery, M.L., R.L. Wick, and J.L. Peterson. 1995. Compendium of Flowering Potted Plant Diseases. APS Press, St. Paul, MN.

Jones, R.K. and D.L. Strider. 1985. Bedding Plants in Diseases of Floral Crops, Volume 1. Chapter 1. Praeger, New York. D.L. Strider, ed.

This information was developed for conditions in the Northeast. Use in other geographical areas may be inappropriate.

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