As a desert plant, the jade plant can withstand droughts quite well, but occasionally falls victim to disease. Although normally a hardy plant that can live for many years, bugs and over watering can lead to their death.
Two diseases can befall a jade plant, including oedema, where roots take up water faster than it can be used, and powdery mildew, the result of an overly-humid climate.
Oedema takes the form of small blisters on lower leaves, and powdery mildew is identified by spots with powdery coating on leaves.
Powdery mildew can sometimes be mistaken for dust on the leaves, but can be distinguished corrected by a microscope under the eye of a plant specialist.
Jade plants that succumb to disease will rot and eventually die if not properly treated.
Avoid over-watering jade plants to prevent stems from rotting, and remove them from areas with high humidity, such as greenhouses.