Fusarium in vandas. Diagnosis and management?

[deanna83]

Hi all,
I got this Vanda online in mid-May in bud. Almost as soon as I got it, it lost about 3 leaves in quick succession from the middle of the stem. And then it stopped losing leaves. Even though there are still a couple of leaves threatening to come off, they've held on for the last month and no obvious progress.
I guessed that this might have been from some trapped water during transport as nothing seems to be spreading too obviously, and also by June the nights were much cooler. The flowers bloomed, the roots seem healthy (though no new growth) and in the last 2 weeks it has started putting out a new leaf.

Now after much reading I've realised this could potentially be Fusarium... But can it affect only the middle of the plant?? If the stem was affected would it still be pushing out this new leaf? I suppose if the roots and core was intact, nutrients can still transfer....

I'm not quite willing yet to cut anything for diagnosis so wanted to see opinions on here. I'm sure it's some sort of rot, which I would hate to spread through the rest of the plant (or worse, to other plants). Should I spray it with something? Any suggestions?!