Under northern conditions where low temperatures for a rather long period are sometimes experienced, injury to the portion of the trees above ground may occur as a result of drying out of the wood. It is well known that a cake of ice will gradually evaporate and disappear when in the open and exposed continuously to below-freezing temperatures. We all know that the family wetwash when hung on a line and frozen will soon dry, especially if the wind blows. The principles operating in these cases may cause severe injury to trees. In the wintertime the root systems of trees take up water from the soil that is not frozen and this water moves in the tree to replace that lost by evaporation. Under conditions where the soil is frozen to such an extent that the water absorbed by the roots is continually less than that lost by the top of the trees by evaporation, drying out of the top occurs. If this is continued over a period of time a dryness of the wood and other tissues occurs that causes death of the dried-out portions. This type of injury does not show the typical symptoms of cold injury but rather those of drying out. The conditions that are most likely to cause such injury are a soil frozen to the effective rooting depths, a dry atmosphere, and a moderately high wind velocity. Injury of a similar nature to that just described very often affects trees transplanted in late fall or early winter, especially those that did not have their tops cut back to balance the loss of roots sustained in transplanting. During even very mild winters the tops of such trees dry out to such an extent that the small branches and even the leader may die. In extreme cases the entire top may die back to the root. In planting bare-root trees regardless of the time of the year they should be rather severely cut back immediately after transplanting to prevent such drying out and dying back of the wood. Cut-back trees generally will make more growth the first season following transplanting than will similar trees not cut back.