Except for the removal of dead branches, pruning is not generally recommended in the case of well grown rubber trees. Weak drooping branches which prevent the access of sunlight to the tapping area may, however, often be removed with advantage. Formerly a process known as thumb-nail pruning was advocated, in which the terminal bud of the tree was nipped off when a height of 12 to 15 feet had been reached. The result of this treatment was to cause a forking of the tree into two or three main branches, and it was claimed that the rate of increase of the girth of the main trunk was thus accelerated. The objection to the method lies in the fact that the fork becomes a point of weakness, and the tree becomes very liable to split at this point if at all exposed to wind. Such a fork also forms a convenient point of lodgement for fungus spores, and may thus lead to the origin of disease. The method is specially to be avoided in countries where Pink disease is prevalent. One form of pruning is, however, often necessary in the case of young trees, especially when widely planted. Any lateral branches which occur below a height of about ten feet should be cut off flush with the stem as early as possible, in order that the future tapping area may not be obstructed.