A gardeners' phrase for a disastrous rotting of plants, especially of seedlings and cuttings, and commonly at the surface of the ground. It is usually associated with excessive moisture in the soil and air, with high and close temperatures, and sometimes poor light. Such conditions weaken the plants and allow them to fall a prey to the minute parasitic fungi which live upon the decaying vegetable matter in the soil, and can remain alive for months, even if the soil is thoroughly dry or frozen. A whole bench of cuttings may be ruined in a night. The skilful propagator takes every possible precaution. His benches have perfect drainage, he uses fresh sharp sand, and sometimes sterilizes it with steam heat for several hours. Damping-off is one of the most trying experiences of the beginner, and nothing can prevent it but a thorough grasp of the principles of greenhouse management in general, and watering in particular. (Consult articles on these subjects.) As soon as the disease is noticed, the healthy plants should be removed to fresh soil, as the disease spreads rapidly.

If the disease appears in the entire bed, the organisms causing the trouble almost certainly are distributed generally in the sand, and sterilization either with formaldehyde solution (40 per cent strength diluted one part to fifty parts water) or with steam should be employed in all future work. If only a spot here and there shows the trouble, saturate the affected area at once with formaldehyde solution, as above, or with copper-sulfate solution (one part by weight to one hundred parts of water). One of the commonest occasions of damping-off is the sudden flooding of a bed or bench after leaving it too dry for a long time.

The terms damping-off and burning are also used for ruined flowers. Burning is often caused by sunlight or by imperfections in glass, but a flower spoiled by dripping cold water, or by some unknown cause, is said to have a burned look. D. Reddick.†