VISIBLE DAMAGE
A Bartlett Pear with limited tannic acid will show small black triangles in the
indented areas under the buds on the tree trunk. It is as if the tannic acid gathered at this location as it
moved up the trunk. This area is dead. With more tannic acid, you find black striped areas very parallel
with the tree. More acid will bring a blistered look like they have been near a hot fire. High acid brings
on lesions in the bark. Most standard pears do not show any damage unless very high acid.