Damping-off is the rotting of seeds in the soil and destruction of newly emerged seedlings by fungi. The entire seed may decay before germination or the seedling may rot just below the soil line. Older plants are usually not killed but often develop stem and root rots. The fungi most often causing this disease belong to the Pythium, Fusarium, and Rhizoctonia species can also cause damping-off.

Conditions Favoring Damping-Off

• Excessive soil moisture and excessive overhead misting.
• Low soil temperatures before germination (below 20°C or 68°F).
• High soil temperatures after emergence (above 25°C or 77°F).
• Overcrowded flats or seedbeds.

Control in the Greenhouse

• Start seeds and cuttings in pasteurized soil or a soilless mix using only sterile flats or pots.
• Do not contaminate soil or containers by placing them on floors or dirty benches or by using dirty tools.
• Buy fungicide treated seeds or treat the seeds yourself.
• Supply bottom heat so that the soil in the containers is 70-75°F (22-24°C).

Fungicides Recommended to Control Seed and Seedling Damping-Off

Determine if a fungicide is registered for use on your particular crop. This information is on the product label.
Captan is cleared for controlling damping-off of many vegetable and ornamental crops.

Fungicides Recommended to Control Rots of Cuttings

Certain fungicides in certain rooting mixes can inhibit root initiation and development of specific cultivars. It is best to avoid the application of pesticides to cuttings being rooted. If fungicides are required, it is suggested that only a portion of the crop be treated the first time this is done. If no inhibition is noted, it is safe to use that specific chemical on that variety of crop rooted in the specific medium used. The following materials can be used on the crops for which they are labeled: etridiazole + thiophanate methyl (Banrot*), etridiazole (Truban*), mefenoxam (Subdue Maxx*), metalaxyl, (Subdue 2E*), propamocarb (Banol*).

*Trade name