I wonder if supplemental feeding with a sugar solution wouldn't help, since that's essentially what the fungus produces to nourish the plants. In that regard, many Paph growers deflasking don't use fungicide in the process whatsoever, believing that beneficial mycorhyza would be destroyed. Instead, a 10% sugar solution is used in which to soak plants prior to compotting. If you could legally get hold of a Platanthera to cultivate, I'd be really interested to see if sugar suplementation doesn't keep it going just fine (neat experiment, if you can manage to get hold of a plant...)