[header] How to identify glasshouse diseases [title] Deal with damp-off. [step] Damp-off or damping-off is a fungal disease that attacks seedlings. The disease attacks at the soil level of the seedling, causing it to collapse. 
The reality of glasshouse growing is that an almost perfect environment is created for this fungus, especially when the glasshouse is damp and seedlings are overcrowded. To reduce the chances of damp-off, ensure that the glasshouse is well ventilated and kept at a constant temperature.