help me save this dendrobium nobile

[djuna]

hello, new member/beginner living in Finland here. i desperately need some rescue advice for a dendrobium nobile. the owner for whom i bought the orchid as a present last year in april, has a habit of watering her plants too seldom. when she does water her orchids, she prepares a deep bowl with rainwater and fertilizer and leaves each orchid in the bath for up to an hour.

in june the two canes were already shrivelled halfway up but at the same time two new healthy-looking canes at the base had appeared so i did not see any reason for concern. come winter, however, one of the new canes has turned dark olive and fallen over. i believe it was rotten through and cut it off. it had been kept on the east window all of autumn and winter.

an inspection of the roots shows much white dried dead-looking bunches but others also firm and alive. the potting material is a combination of bark but mostly fine peat-like material; much of it has white mold at the top and sides but not inside the "rootball". in the last two weeks i have only watered it twice without soaking.

combined with the roots, the look and feel of the bigger canes worry me. as for the remaining new cane, i think it is also rotten through, the top third is firm and green but the middle section has begun to hollow out.

in panic i have already removed the orchid from the pot and loosened the potting mix to let the roots dry out a little.

i would really like to try and save this poor thing and would appreciate all the advice i can get.

winter skies,
djuna