Lately, there have been many cases of dieback on a fairly popular evergreen tree, the Balsam Fir (Abies balsamea). Symptoms have been primarily dead or dying tops of trees. Abiotic conditions (drought, wind, environmental) are most likely the main cause of this.
Affected trees are likely to recover. If the tree has a dead top, it will most likely form a new leader. Watering and mulching trees will improve health and vigor.