Okay. That could be it- although I am a bit erratic with fertilising. Maybe I've been forgetting to give it a break every so often.
I have been taking my orchids to the sink and running 3/4 of a litre or so through them and then sitting them on the draining board. The water in Edinburgh is very soft, but we have a dehumidifier in another part of the flat as it was VERY cold and damp when we moved in. I have been using the water from it to water the orchids as the temperature of it is better.
In this case the damage may have been from earlier care, thinking back I seem to rememver similar roots on this plant when I repotted last June.
Live and learn.
