Phytophthora -infected roots have a pungent, but not necessarily unpleasant order. Root-destroying enzymes cause the roots to become mushy. During later stages of disease development, one can squeeze liquid out of infected roots. Severely diseased roots may disintegrate rapidly, reducing yield considerably. These discolored roots greatly reduce the market value of the crop.
Oospores can survive in the soil for many years, even in the absence of ginseng.
Although Phytophthora cactorum can infect many plant species, the importance of other crops, woodland plants, or weeds in the disease cycle of Phytophthora root rot of ginseng is not known. In the spring, oospores germinate to form the thread-like network of fungal strands called the mycelium. These short-lived zoospores require a film of water in order to swim from their point of release in soil to a ginseng root. When they arrive at the root surface, the zoospores become cysts that germinate to form a mycelium inside the root. The fungus produces more sporangia on the surface of the infected root that release zoospores during wet soil conditions.