Symptoms and Signs
Seedlings affected by damping-off fail to emerge or fall over and die soon after emergence. Stems usually have a dark, shriveled portion at the soil line. Damping-off is generally limited to areas where drainage is poor or where soil is compacted. Because almost all eggplant plantings are with transplants, this disease is of more concern in the greenhouse if a potting soil is contaminated, overwatered, or both.
Comments on the Disease
"Damping-off" is a general term for the death of seedlings, either before or after emergence, under damp conditions. Because almost all eggplant fields are transplanted, damping off is more of a problem in the transplant nursery. Infection is most common under cool conditions. Once eggplant seedlings reach the 2- or 3-leaf stage, they are no longer susceptible to infection by Pythium or Rhizoctonia; however, Phytophthora can infect eggplant plants at any stage. Damping-off caused by Pythium may increase where green manures such as volunteer grain are worked into the soil just before planting. Damping-off does not necessarily carry over from one season to another in the same places but appears only when and where conditions favor infection.
Proper seedbed preparation, potting mix disinfestation, and good water management significantly reduce losses from damping-off. By using sprinklers for germination, you keep better control of water and lessen the chance of infection. If possible, avoid planting when the soil is cool; seeds germinate faster and seedlings are more vigorous when the soil is warm, so they are less likely to be damaged.
Solarization and steam treatments of potting soils can significantly reduce levels of soilborne pathogens before planting seeds in the nursery. Use clean disease-free soil or mixes for planting. For more information, see Soil Solarization for Gardens and Landscapes (PDF). See also, Soil Solarization: A Nonpesticidal Method for Controlling Diseases, Nematodes, and Weeds (PDF), UC ANR Publication 21377.