Murray is right to emphasise that Nosema is very much stress related.  The
main limb of any treatment must be to identify and remove the causes of
stress.  If the beekeeper through his practices is the cause of the stress
and for reasons of his own finds this unavoidable then I agree that the use
of Fumidil is probably the best compromise.  It has been used for so many
years now that I wonder why resistance has not arisen.
Chris Slade