How do I encourage root growth?

[monivik]

This is a bit of a continuation the the other threat about the mealybug infestation that I had.

This Schilleriana, a young plant, so it's quite small compared to my regular Phalaenopsis. As I've told in the other stories I bought it end of June. Anyway I think that I've got the mealybug problem under control now. I've sprayed the "insect control" stuff, the poison twice... I keep checking just in case but so far I don't see any more bugs.

Anyway... this is the situation now: most of the roots are completely desiccated, dried out from the top. The outer edges are still green but the upper part dried out. As you can see on the picture. Except for 2 tiny new roots, that are too short, they're not in the medium yet.

So my question is: what can I do to promote root growth?