blossoms dropping off egg plants (aka aubergines)
 

I have a problem with my egg plant blossoms. They fall off while in
full bloom. The stem of the blossom is severed about 15 mm behind the
blossom itself.

Looked at the break with a lens. It looks like it has snapped, rather
than been eaten through.

Have put down snail bait in case the weight of a snail is snapping the
stem.

Does anybody have any suggestions about the cause of the problem?