This...

[bigroth]

What I really need is a miltoniopsis whisperer. My very mature plant has not been happy since outgrowing its previous pot and being transferred to coarse bark. Anyway, I see this on a few of the bulbs. I want to think it's fertilizer burn vs overfertilization (calcifications?)?? Then again, I always want to think that. I mix a 20-10-20 power at 1/4 teaspoon per gallon of water 2x per month (1/4 recommended stength). Otherwise I water weekly- 6 inch pot. Prob overkill? Why must I love milties so much?

[WhiteRabbit]

Is it just old growth getting this?

[bigroth]

Originally Posted by WhiteRabbit

Is it just old growth getting this?

Im not certain if they're old growths, they tend to be on the periphery

[WhiteRabbit]

Are you referring to the black areas? Are they firm? I've sometimes gotten similar on some orchids, and it's not spread, nor seemed to harm the plants (tho I can't say for certain yours is the same) I don't know the cause - mineral deficiency, perhaps?
Does your fertilizer contain minerals? Do you water with tap water, or pure?

Do you flush the media well once a month?

I hope some other members will be chiming in to better help you ...