Ask your teacher to show you a case of fire-blight on a pear or apple tree.
Of course they had no reason to sue us because the damage was clearly done by fire-blight.
A large pear-grower once said that no man with a sharp knife need fear the fire-blight.
The fire-blight bacteria grow in the juicy part of the stem, between the wood and the bark.
You have perhaps heard your father speak of the "fire-blight" of pear and apple trees.
I have a whole orchard of pears and there has never been a trace of fire-blight.