I have germinated at least 20 different types of seeds this year, both vegetables and annuals. I have used the same sowing methods, starting mix lights etc. for everything.

I am getting damp off in my alyssum starts, but not a sign of it anywhere else. On top of that, they were started on three consecutive days and so ended up in different trays, mixed with various other starts.

Is is possible that the damp-off spores were in the seed packs? Or is it just that alyssum is so tiny when it comes up that it is much more susceptible? There are 3 pots of alyssum that don't have it (yet), but I have tossed or segregated the others. I sowed three packs of seed so maybe the good ones are from an uncontaminated pack?

Everything is young enough that I have only watered once (bottom watered) since they came up, and I did use hydrogen peroxide in all of the water I used to moisten the starter mix. I am (as of yesterday) using a fan on everything a few hours a day. I have true leaves starting on many things, but I haven't repotted anything yet. I am nervous that the contamination will spread, everything else that is up looks so good!