Problems w/ leaf color/drop on Mtssa C.M. Fitch 'Izumi' and Phal. Ever Spring 'Pearl'
 

On my Mtssa C.M. Fitch 'Izumi' some of the leaves keep turning brownish at the tips, then the color progresses and the leaves fall off. So far, I haven't worried about it because there is some new growth that this isn't happening to. This is in spike right now. I just figured I'd ask because the tips of the two spikes have turned brown and I have no idea why (maybe the two issues are related?) I have no idea, this is my first non-phal orchid. I bought it this summer. Is this normal for this type of orchid?

Secondly, I have a Phal. Ever Spring 'Pearl' which I rescued from the same nursery as the Mtssa mentioned above. Unlike the Mtssa, I've had phals for years. It was in horrible shape when I got it, sitting in sopping wet peat moss, with most of its roots rotted. Since I repotted it in bark, it's made a great come back-lots of new roots and even two spikes! It's in spike right now with a few big buds (I accidentally broke off a young spike 2 months ago when I was moving). The past 2 weeks or so I have been concerned about its health. Two leaves have turned yellow and fallen off and one is in the process of turning yellow. I have no idea as to what is causing this. It is not in the normal way a phal looses it's leaves--they are still pretty fleshy, but yellow.

What is wrong with my two plants?
Any help is greatly appreciated.
Thanks,
Haeleigh

pics to come if they are needed and I can figure out how to get them up.

How often are you watering each plant?
Joann

Each is being watered once a week. Both are grown under lights, but the phal is not placed directly under them.

I recently took the phal out of its pot to check out the roots, and there was some rotting, but not much. I cut the rotted roots off and repotted it in a better draining pot (I found that the pot it was in wasn't providing very good drainage--it was a little soupy). Could this have been the problem with the phal?

Phals do not like their roots constantly wet and they do like air circulation. This could be your problem.

What are the pbulbs like on the mtssa?
Joann

sorry it took so long to respond--I don't have internet at home for the moment, but I do get my email sent to my phone--so I did get your response when you posted here.

The Phal had crown rot. I was concerned because leaves were still turning yellow and falling off even after repotting and the introduction of a fan to the room. I never left water on the crown...so maybe the root rot spread upwards? I cut off as much of the rot as I could today, and I'm left with 3 leaves and 3 small roots (which were aerial). Maybe it will survive, but I'm not too hopeful--I had to leave a TINY bit of the rot because if I cut any higher it would've gotten rid of the remaining roots!

The Mtssa is doing better than the phal, but not well. Leaves are still dropping. I have several pbulbs with no leaves now. However, the pbulbs look nice and healthy-no wrinkles and nice and big. I think it might be good to mention that it is mostly the bigger pbulbs losing leaves--and leaves are still on most of the smaller pbulbs. Is it possible that this may be part of the natural aging process? I am so worried!

Also, the new leaves on the Mtssa are turning slightly yellow--could this be due to the fact that it is newly under lights (for the past month or so)? I took it out of it's pot to check roots today, and everything I saw looked good--as far as I could see, no rot. any ideas or suggestions?
Thanks for your help!