The mysterious disease, which dried up over 800 mature deodar trees in the Chail (Shimla) area over the past five years, has been caused by Phytophthora cinnamomi, a deadly fungus known for its destructive potential the world over. The fungus identified by a special team comprising scientists of Himalayan Forestry Research Institute and the Himalayan Research Group, a non-government organisation, has been reported for the first time from the Himalayan region.