Some links in this post may be affiliate links
Damping Off Disease is a fungal disease which attacks the root and stem bases of seedlings.
The disease causes shrinkage and rot at the ground level which causes the seedlings to topple over.
Damping Off Disease is prevalent in damp, warm and poorly ventilated conditions.
It spreads very fast and may cause the loss of all your seedlings if immediate control measures are not taken.
1.Damping off disease is not easy to deal with as it spreads very fast. The best way is to avoid it by; use of sterilized soil and containers, avoid overwatering and sow seeds thinly to avoid overcrowding of seedlings.
2.On noticing the first collapsed seedling; improve ventilation, reduce watering and move your seedlings to a cooler spot.