That is a pretty pathetic cutting! Herrenhauser Garten always had very corky bark as the wood matured. I've seen injuries do that also. When I had a power outage late January, those damaged branches that survived developed that look. Fred is very good at diagnosing problems. Maybe he can chime in and tell you if that could endanger you collection. At the very least, I would isolate the cutting.
Personally that does not look bad...it looks like a cutting from a branch that is transitional...becoming corky...SB looks much more menacing...dark and infective looking...some plants like pink smitty, or peanut get that corky look but not dark or infective. When you see stem blight it is usually obvious...this cutting to me just looks transitional...but i would isolate it if you have doubts and watch it closely...personally from experience, i think it's just getting ready to transition to a corky phase...there is no blackening or darkening as far as i can see...looks more like injury than infection...but when in doubt...ISOLATE!!!
No here is the 3 cuttings I have Felicity its does the cork thing too this is not that. Not where the plant was hurt scraped nope this is something else. This person sent me 3 different sets of cuttings different plants they all have it proably don't even know to clean the clippers between plants
I agree with you, there are a lot of new brug growers and they have no idea how fast they can be infected using the same cutters without putting them in some salution befor cutting another one, I always had a dish of bleach and water and laid the clippers in it after every cut, even on the same plant.