Urban and wild trees in the United States have often been
subjected to diseases and destruction by pests, microbes,
drought, storms and fires. But instances of certain pests or
microbes affecting a particular species of tree on a large scale
and threatening to wipe them away are more problematic. Chestnut
blight is caused by Endothia parasitica and have almost wiped
out chestnut trees from the eastern hardwood forests. The spores
of this fungus are spread by winds, birds, rain and insects.
They attack the tree through any external injury; the cankers
kill the cambium and cracks are formed on the stem. Decades of
research has not resulted in any appreciable result in curbing
this disease. Butternut trees, also known as white walnut, are
mostly found in north eastern forests of America. The wood from
butternut trees is used for making furniture. The fungus that
causes butternut canker is called Sirococcus clavigignenti-
juglandacearum. It attacks the tree through the buds or an
opening on the surface caused by i