I've considered that also. I know the commercial guys will spray preemergent to kill off weeds in their fields. I am a little hesitant in doing that though. Perhaps it is just a hurdle I've not yet jumped so am just overly apprehensive.
Traditional wisdom suggest that we can spray for weeds either before the ginseng emerges in the spring, or after it lies down in the fall. Of the two, I would think spring spraying will be the more productive because you will be spraying actively growing plants, not plants which are themselves becoming dormant. The danger of course is that you have some early emerging ginseng which will get sprayed and also that the residue on your mulch might negatively affect the ginseng as it emerges and comes in contact with the spray chemical(s).
I have one patch that looks like a bed of grass with ginseng in it. This is because I used straw mulch, and the straw in that bail was less than clean. I will likely spray that next spring in an attempt to kill off the grass ahead of the emerging (will be) three year olds.
If you spray this fall...please let us know how it works out.
