Using a soilless mix helps prevent this fungal condition. Stay away from unsterilized soil, compost, or worm castings until the seedlings are ready for transplanting. If the seedlings must remain in the container for a while, fertilize with a weak solution of fish emulsion or seaweed. The first step in prevention calls for cleaning containers and tools in hot, soapy water. A top layer of perlite will keep moisture away from emerging stems.
Some gardeners advocate covering newly sown seeds with plastic to maintain moisture.
If you try this method, be careful not to produce a jungle environment because too much moisture and warmth will promote fungal growth. If you spot any mold or fungus, uncover the seedlings immediately.