UC IPM Home > Homes, Gardens, Landscapes, and Turf > Quick Tips > Damping-off of Seedlings

Pests in Gardens and Landscapes: Quick Tips

When seedlings of vegetables or annual flowers die soon after germinating, the cause is often one of several pathogens that cause damping-off disease. Seeds may rot before they germinate, shoots may decay before they emerge, or stems of seedlings may rot at the soil line. Damping-off is most common when conditions are wet and cool and soil is compacted. Manage damping-off by planting at the right time, germinating seeds indoors in disease-free soils, and following planting practices that reduce risk of the disease.

Roots on plants at right have been damaged by damping off pathogens.

Plant when temperatures are favorable for rapid seedling growth.

• Don't plant into cold, wet soil.
• If you want to start plants earlier, use transplants; plant seeds indoors and transplant later.
• Shallow planting will speed up germination outdoors if conditions are marginal.
• If planting potato seed pieces, be sure soil is at least 50°F.

Reduce water-logging in planting beds by improving drainage.

• Use raised beds.
• Add soil amendments such as redwood shavings, peat moss, or bark.
• Avoid green compost.

Apply good cultural practices for seedling plants.

• Don't overwater.

Seedling at left has been killed by damping off.
• Thin plants after they emerge to improve air circulation.
• Don't overfertilize with nitrogen.
• Avoid planting the same crops in the same place year after year.

Employ good sanitation practices.

• Use clean pots.
• Remove and discard diseased plants.
• For plants grown in pots or cold frames, use steam-treated soil or pasteurized potting mix.
• Outdoors, consider solarizing soil before planting, a method that uses the sun’s heat and clear plastic to kill soil-borne pests.
• Use the highest quality seed available.

Minimize the use of pesticides that pollute our waterways. Use nonchemical alternatives or less toxic pesticide products whenever possible. Read product labels carefully and follow instructions on proper use, storage, and disposal.