Damping Off

Last updated: June 7, 2021

What Does Damping Off Mean?

Damping off is a common horticultural condition caused by several soil-borne types of fungi or fungus-like organisms such as phytophthora, pythium, rhizoctonia, and fusarium. Damping off occurs most often in moist, cool conditions.

Damping off is most recognized in seedlings as a rotting portion of the stem beginning down at the base of the plant and extending upward.

Melon seedling affected with damping off plant disease


Maximum Yield Explains Damping Off

The first sign of damping off is usually a mushy stem and dropping leaves (which can be mimicked by many other conditions). Eventually, the stem will weaken and begin to topple over, and the leaves will die. Afflicted seedlings often fail to emerge from the soil or they decay and collapse shortly after emerging. Growers frequently notice a pile of white fungus around the sick seedling and on the soil’s surface.

Once the process has started, there is nothing the grower can do to prevent damping off from killing the plant(s).

When a plant has matured and has leaves and a strong stem, it is usually able to overcome the stress of excess moisture and is not as prone to the fungal pathogens that cause damping off.

Damping off is common in locations with high humidity, poor air circulation, and cool, wet conditions such as the overwatering, or when the seeds are not adequately spaced when sown. Germinated seedlings that aren't properly 'hardened off' before being transplanted outdoors in the early spring are also more susceptible to the condition.

Growers often suffer the most severe losses from damping off during the spring months when both the light level and the temperature are low because the seedlings grow slowly in such conditions which make them more vulnerable to fungus infections. However, if the conditions are right, damping off can occur at any time of year.

Growers can take many steps to prevent their seedlings and cuttings from becoming victim to the fungus such as growing only in soil that is free of fungi. New pots and trays should always be used when sowing fresh seeds. Spread the seeds thinly to prevent overcrowding. if growing indoors or in a greenhouse, the space should be well-ventilated with humidity controls. Make certain planting beds or containers are well-drained and that young seedlings are protected from heavy rainfall in early spring. Finally, avoiding over-watering seedlings and cuttings also helps prevent damping off. Old seeds also appear to be more susceptible to damping off.



Damping-Off Fungus

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