Present in almost all soils, the various organisms referred to as damping-off fungi can kill seedlings sometimes even before they emerge, and rot potato seed pieces. Healthy seedlings resist infection, though, and plants generally become less vulnerable with age. Over-watering and poor air circulation foster the growth of damping-off fungi, and plants are more susceptible to the disease in wet, poorly drained, cold soils with a high nitrogen content.
Seeds, young plants.Damage:
Seedlings fail to sprout; or they may die soon after emerging.Control:
Proper drainage, planting, and watering.Notes:
The fresher the seeds, the less likely they are to fall victim to the disease. You may also want to try seeds treated with a fungicide. Plant seeds when the soil temperature favors growth; set them at the right depth, leaving adequate space between seeds. Don’t over-water, and hold off on fertilizing until seedlings have true leaves (not just initial seed leaves). To improve your chances of success, you can start seeds indoors in a sterile planting mix, then transplant the seedlings outdoors. Sanitize your propagation tools, pots, and flats in a solution of nine parts water to one part bleach or rubbing alcohol.