>I read in Michael Bush's link to not dust with powdered sugar when it is either too hot or too cold.
That was from Nick Aliano's research and he was chasing the bees out of the hive with a fume board and treating them in a cage. It's not so much the outside temperature as the temperature of the bees. When it was hot, but not too hot, he got the most mite drop. When it was not very hot, he got a lot less mite drop. When it was too hot the bees stressed, barfed, turned into a sticky mess and many died.
>I was hoping this method would work in the winter when there was little brood
It will be more effective when there is not brood, but it will also be more effective when the weather is warmer.
>Am I correct that dusting with powdered sugar will not contaminate honey?
I should not contaminate the honey even if supers are on if you only put it over the brood nest.
>Does anyone know of a site that is a great source of information for dusting?
Try a search on here. There has been much detailed discussion. Also try here:http://www.countryrubes.com/instructionspage4.html