black spots on dendrobium atroviolaceum
 

dendrobium atroviolaceum with black spots on tips of several leaves. I live in Maryland and plant is in east facing window. temperature today was 75f and humidity 68. orchid planted in bark with saph moss on top. I also noticied black spot on one leaf where it joins bulb.

Mine all have some spots. During the growing season, water often. Twice a week is not too much.

Don't let it dry completely, ever.