AbstractDirect and indirect evidence related to “top‐dying” of Norway spruce is presented along with theoretical considerations to construct a hypothesis explaining the cause of the disease. It is thought that “top‐dying” is primarily caused by severe water stress created by adverse climatic conditions chiefly mild, windy weather during the dormant period reinforced by drought in the first part of the growing season. When such conditions occur for more than two consecutive years severe outbreaks of the disease