Using fungicide on young seedlings

[snappybob]

I have young seedlings (2 weeks old) in my greenhouse and the weather has been very moist, soupy and rainy for a lot of that time. We've had a few days of sunshine and sometimes the sun breaks out late in the afternoon but I worry about a fungus infection in these conditions. I am very hesitant to spray such young seedlings with anything but I would hate to lose them as well. What, if anything, should I be using under these conditions. The seedlings look healthy. So far.
Thanks