Guignardia fungus prevention?

[Jayfar]

Does anyone here find their Neos are susceptible to the same Guignardia fungus, characterized by black leaf spots, that seems to be very common among Vandas generally?

None of my Neos have any significant spotting, most none at all – YET, but it's pretty likely that my small number of Vandas all have Guignardia fungus present to some extent, unless the tiny black spots are something else entirely. I'm a little concerned that if my Vandas do indeed harbor Guignardia that they are likely to eventually pass it to my nearby Neos, which of current necessity live very close to the Vandas at the moment (they'll be moving across the room in the winter). I had already removed the worst spotted lower leaves from my 2 biggest Vandas.

Would it be a good idea to use a preventative treatment of Cleary's 3336F. I've seen some recommendations to alternate Cleary's or any other systemic containing thiophanate methyl, with a non-systemic such as Mancozeb.

I generally prefer to use chemicals as little as possible, but on the other hand I do want to minimize any risk to my Neos, since they're all about the foliage.

So I'm putting the question out here to the experienced long-time Neo growers. What are your experiences regarding Neo susceptibility to Guignardia and other nasties and what, if anything, do you use as preventatives?