The saguaro is a long-lived cactus, most affected by long-term climate cycles of frost and drought. Reports of a saguaro "disease" popularized almost fifty years ago, but saguaros are not subject to blights. The saguaro is a common plant in the Sonoran Desert and is not an endangered species.
Without question, the biggest threat to the saguaro is our rapidly expanding human population. The development of new homes in the Tucson area has resulted in a tremendous loss of saguaro habitat.