If feeding frames of honey back to bees was a major cause of AFB then there wouldn't be a hive left in New Zealand because they all would have been burnt years ago.
thats a bit silly. it doesn't "cause" afb, its just one method of spreading it.
Feed honey taken off properly checked hives
and thats the caveat. often those with afb problems are due to lack of properly checking hives. however its easy enough to miss especially with poor mite control which is common with organic mite treatments.
Feed honey taken off properly checked hives is less of a risk than feeding sugar. Feeding sugar especially with the hordes of neighbouring hives will always cause some robbing no matter how careful you are , and robbing is a great way to spread AFB.
i disagree a bit, simply because they are robbing sugar, not infected honey.
its not until they are robbing out weak hives, and most likely those hives are weak because they are dying from afb (not going to get afb from a hive dying of something else). which is going to happen regardless of how they are fed.
the simple thing, transferring of gear and especially feed, is a very good way to spread afb and turn a small problem into a big one.
add in the fact that so many organic beeks are beginners, and the afb course is given to beginners, its really bad form to be teaching them how to beekeep badly from day one. they simply do not have the inspection skills or the understanding and attitude towards afb.