Damping-Off on Swiss Chard
Damping-Off on Swiss Chard

Damping-Off on Spinach
Damping-Off on Spinach

Damping-Off in Tomatoes (Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org)



  • Corn
  • Brassica Crops
  • Legume Crops
  • Solanaceae Crops
  • Leafy Greens Crops
  • Cucurbit Crops
  • Potato


Damping-off is caused by several soilborne fungi including Pythium, Rhizoctonia, Fusarium and Phytophthora species. The fungi kill seedlings that are just germinating and seedlings that have been growing for several days.


Fungi causing damping-off are soilborne and can be found anywhere even small amounts of soil and dirt are left including reused seed trays and benches. Once the seed is planted and watered, fungal spores or mycelium will start to colonize the soil in the trays. The chance of having an outbreak of damping off is increased when seedlings are kept very wet. Damping-off pathogens present on dirty greenhouse benches can colonize the soil in seed trays through openings in the tray bottom.


Symptoms vary depending on time of infection. If seedlings are killed during germination, circular bare spots occur in seed flats. If seedlings have emerged, they may look normal the first few days and then the lower stem turns brown or black and the seedling falls over.


  • Disinfect growing benches.
  • Disinfect growing containers.
  • Source sterile potting mix.
  • Avoid excessive irrigation, seedling should not be kept too dry or sit in water for days.


Seed treatments can reduce damping-off incidence. Often seed that is already treated with fungicides can be purchased.

Precautionary Statement: Utah State University and its employees are not responsible for the use, misuse, or damage caused by application or misapplication of products or information mentioned in this document. All pesticides are labeled with ingredients, instructions, and risks, and not all are registered for edible crops. “Restricted use” pesticides may only be applied by a licensed applicator. The pesticide applicator is legally responsible for proper use. USU makes no endorsement of the products listed in this publication.