Here in Washington State fire blight is also spread by rain and over head
sprinklers.  Growers use the sprinklers in freezing weather to put a coat of
ice on the tree to prevent frost damage.  The freezing water actually adds a
degree or two to the tree hopefully raising its temperature above the damage
point.  The pathologist here thinks that these two cause the major part of
the damage, not bees.  After all the bees visit the bloom not the tree.  Of
course when the blight gets to the bloom by the rain then bees could move it
to other blooms.

James C. Bach
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