Alternaria Leaf Blight
Ginseng is susceptible to disease caused by the Alternaria fungus. There is much literature that suggests sprays and control measures. I have not found Alternaria to be as serious a problem as all the literature makes it out. Alternaria is recognized by yellow and brown spots on ginseng leaves. In late summer you see more of it, not only on ginseng but on many woodland plants such as wild sarsparilla, a relative of ginseng, and on blackberry leaves. Late in the growing season, when plants begin to look tired is when you see it. Here is a photo showing the leaf blight on a two-year-old ginseng plant.
I prefer to let nature take its course rather than spray fungicides on the leaves. In all probability, this infected plant will likely emerge none the worse for wear next year. A couple sanitation measures might be worth consideration/ One is to allow space between plants so as to possibly reduce the tendency for the fungus to spread to other plants. Another is to avoid touching an infected plant and then touch other healthy plants. I am not familiar with the research on Alternaria to support these claims, however.