Usually Nepenthes are very resistant against fungi. If
fungi occur that is usually a sign of wrong growing
conditions for the special plant.
When I had fungus problems so far, infections mostly
happened with plants that were standing at a dark spot or
received spraying too often.
In environments that are kept very moist like chambers to
root cuttings fungal infections sometimes spread rapidly.
I doubt however that the seeds were carrying the fungi. It
sounded like the seedlings growing for a while before
infection starts. Fungi which are carried with the seeds
usually affect seedlings while germination occurs or
shortly after; therefor I feel that this is not likely.
However N. vieillardii is a difficult Nepenthes! They grow
nicely for me until they've reached +/-10cm in diameter and
then they become really problematic!
Try to grow them with lots of light in a humid and warm
place.
All the best
Andreas
Andreas Wistuba; Mudauer Ring 227; 68259 Mannheim; Germany
Inet: a.wistuba@dkfz-Heidelberg.de / a.wistuba@carnivor.rhein-neckar.de
Phone: +49-621-705471 Fax: +49-621-711307