When I have this problem, I cut, then use isopropyl alcohol on the cut, then, with a new cotton ball, I wipe the neighboring area (not roots) with alcohol to disinfect and dry. I then dab the area with cinnamon and I then keep the affected plant dryer than normal for a few days. If you have these in moss, maybe using a plastic vanda basket to provide ventilation will then prevent further infection. The last time I had this problem, this fall, I didn't get all the brown removed but it didn't progress. Good luck! I know this can be very frustrating.
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