Are you familiar with the trilium down there? Have you seen them yellow and wither away starting around the beginning of july?
This is Alternaria leaf blite and next year they'll pop up again. If you are growing wild simulated in a perferred area ,this disease is not going to wipe out your crop, next year they'll pop up again. Chemicals are for areas that ginseng does not like or for control of bad seed like shade grown.
Guy