As a result it goes largely unnoticed by growers. Afffected berries will shrivel and the seed may not develop fully. The disease spreads rapidly through a garden. The causal fungus does not require free moisture to initiate infection and high relative humidity is enough to cause epidemic spread of disease. The very first noticeable symptom of powdery mildew in ginseng is spotting of the leaves.
Initial infections appear as small, yellowish spots on the upper side of leaves.
As lesions age they become distinctly white in appearance. Except for the haustoria, powdery mildew infection is entirely superficial. The fungus grows and develops on the leaf surface. The leaf colour is changing rapidly to reds and eventually to yellows and browns. Defoliation will follow.