Re: if you hammer a copper nail into a tree will it kill the tree

It seems to be a common myth that a single copper nail will kill a tree but it 
does seem to be just a myth (see first reference). If the trunk is big 
relative to the nail then there will probably be insignificant damage. Copper 
is not very soluble so it would not poison the tree. The nail might allow 
entry of disease or decay organisms that might eventually kill the tree but 
that is a long shot given that copper is an ingredient in many fungicides.

Driving nails in trees (tree spiking) has been used by ecoterrorists to save 
forest trees (see second reference). Nails in tree trunks cause expensive 
damage to saws and may injure tree cutters so tree cutters do not harvest 
trees with nails in them.

Arborists often cause larger wounds injecting iron or other mineral nutrients 
into trees. 

References



TWENTY OF THE MOST COMMON MYTHS ABOUT TREES AND TREE CARE


Tree Spiking