Question: query regardin nursery management in case of tomato. 
Answer: if you not use any kind of fungicide during the time of seed sowing then please spray trichoderma viridi 10 gram/liter of water or glyodin or carboxin 3gram/liter of water one times throughly in the nursery bed. 

before transplanting deep the root in any one of the above mention fungicide for 30 minutes and then transplant in the main field.