What is Damping off?

Damping off is a condition which sometimes appears in seedlings, especially when the seedlings are grown in containers or in indoor spaces. This condition is characterized by abrupt wilting and failure to thrive, with eventual death of the seedling, and it is caused by fungal infection. There are a number of steps which gardeners can take to prevent damping off, and to manage it if it occurs. Gardeners should also be aware that damping off happens to everyone, including the professionals, so they shouldn't be too disheartened when it happens.

In pre-emergence damping off, the seed fails to dry entirely after it is sown, and as a result, fungus starts to develop. The seed may fail to germinate, or it may germinate but produce a weak, sickly seedling which eventually dies. Damping off can also occur once a seedling breaks the soil, in which case it may be caused by root rot, or by fungal infection around the stem. In this case, the stem typically thins and eventually bends or breaks near the soil surface. Small hair-like structures may also appear at the soil surface.

The best way to deal with damping off is to prevent it. Gardeners should make sure that their garden sheds are kept clean and sterile, and when they plant new seeds, they should use clean soil and sterilized planting trays. The soil should be moist, but not totally soggy, and the seeds should be sprinkled at healthy intervals. When seeds are packed close together, they tend to be more prone to rot and damping off. Once planted, the seeds should be covered in a layer of light material, and some gardeners use substances like small gravel or sand at the very top layer of the soil, to promote drainage.

It is also important to maintain good circulation in areas where seedlings are started, as this will help the seeds dry out. Overwatering can also lead to damping off. Gentle misting is usually enough to encourage germination. If signs of damping off do emerge, the infected plants should be removed and destroyed, and the remainder should be isolated so that if they become infected as well, the infection will not spread.

Some people use fungicides to prevent this problem in seedlings. While this is an option, fungicides need to be used carefully, and no product can target every possible fungal invader. Good horticultural practices can prevent damping off in many cases, as can keeping a close eye on seedlings to monitor them for any signs of ill health before fungal infections get a chance to spread.