Masdevallia, discolouring, underside of leaves

[headbanger333]

i have a Masdevallia which is on a southfacing windowsill getting good airflow and early morning sun. The underside of several leaves have recently developed brownish stain. They are otherwise ok. They seem to get this colouring as they age. They are all green as they start growing then the under side discolours. Don't know which Masdevallia it is. Any ideas?

[estación seca]

Hard to say without photos... what are your temperatures day/night and humidity? I would worry primarily about spider mites.

[headbanger333]

i am in New Zealand so in summer time. Our summer temps can reach 28C and it can be quite humid. Although they are on a south side windowsill with window open all the time, they get the morning sunfor 3 hours. This is the coolest place I've got.