I generally do a 50/50 mix of old & new soil, but if the old soil is contaminated with hplvd, the problem will never go away.I have been using the same soil outside for a decade. Cover crop, A lil amending, some EWC and compost and away we go.
I have not heard anything about whether there's a preference for indoor vs outdoor.I'm curious if darkhorse nursery pinpointed a set date in time of when it began with them (not when it was noticed), was it in their stock for a long time being bred by them unaware, was a lot of their stock indoors/out originally... I know you can bring it outdoors/vice versa for sure but it usually pops up mostly indoors right? from pest pressure and no diversity/competition as with outdoor biodynamics, or infected seed, contact etc. but really it shouldn't be outside i'm getting but does exist outside, unless in a particular microclimate that is very stagnant/overcrowded and such?