As much as this sucks, I think I know what the problem is … when I watering water is dripping from the orchids hanging above these guys. With this many plants in the nano the fan probably can’t get enough air circulating in there anymore – hince this problem. I was afraid of this (see earlier post).
To quote Lassse (freely translated from swedish): “Masdevallia are sometimes described as an extremely moisture-loving genus but it is a truth with modification, I think, a lot of species have fairly thick leaves and do not need dripping wet humidity, least of all this season.” Tuerckheimii and guttulata are both fairlty thick leaved I would say. Thanks for the wisdom Lassse!!
Remedy: I’ll cut off the badly infested leaves and then spray with a little Fungital (really mild anti-fungus stuff), then move the plants to another place with better circulation – and no dripping water. I also adjusted the fan so that it pulls in a whole lot more air (rather than just circulating what’s in there). RH has been at 80-90% but now it usually settles around 70% (80% when the watering system is running). If necessary, I may install one more fan someplace… but where?