Close to the base of the target tree, hammer in a copper nail at a slightly downward angle. There is no rule about the size when selecting copper nails, but in general, the greater the surface of the nail with regard to the length and width, the more effective the treatment. In addition, a longer nail means deeper penetration, resulting in a greater likelihood that the tree is sick. Next, hammer the nails into a ring around the tree, about half an inch (1.3 cm) away. This increases the number of damaged growth cells and the concentration of copper in the tree. This higher concentration is better, because this increases the possibility of the oxidation of the metal, which poisons the tree. The idea that one copper nail will kill a tree applies only to very small trees such as seedlings. Larger trees can tolerate a single nail without any problem and it is easy for it to grow over the nail over time with no harmful effects. Optionally cover the nail heads with mud? The purpose of mud-covered copper nails is to hide the nails. Copper has a tendency to show clearly at the root of trees because of its bright colour. Covering the nails makes the process less obvious to a casual look and can preserve the appearance of a halo as the tree begins to die. With mud to cover them but not completely hide the fact that something has been done to the tree. After the tree is dead, remove the nails, before removing the tree. Otherwise, the nails could fly and injure someone, or they could damage the machines used to remove the tree; there are many nails.