Oncidium with brown pseudobulbs
 

Hi folks, I'm a newbie here and only started getting into orchids a year ago, mostly brassias, oncidiums and various hybrids. So far, no fatalities and generally all are doing fairly well. I have recently received a (small) oncidium phymatochilum that I bought online, but all its pseudobulbs are brown, with the largest only half brown (the top half). It does seem to have some new growths that are also brown-ish, but I was hoping somebody could identify the problem (if it is a problem). By the way, the brown bits seem dry and firm, but the brown part of the two-tone pseudobulb is half the thickness of the lower green part.
Thanks very much!

It looks like pigmentaion from the light levels but a closer photo would be nice (of the pbulbs and the new growth).
Let me add, the medium seems to be a bit dry, although the pbulbs are not wrinkled.

BTW, welcome. :)

More pics
 

Hi, and thanks for the reply and the welcome! I have added more pics that are a little more "zoomed-in". The one with the yellow arrows just indicates the brown part of the pb, because the colour doesn't show up on that pic. You can see that it is much thinner. I soaked the plant for 15 mins when I received it 4 days ago - I think the green part swelled then, leaving it thicker than the brown.

There are several photos online that show the same characteristic so I'm tempted to think the plant is like that.

Anyway, a few questions...

The brown areas are soft / mushy?

If I understood correctly, you recieved the plant like that. Am I correct?

Firs, Welcome!

If you just received it... it is very likely that it got too dry. In time, the older pseudpbulbs may shrivel, providing energy to the newer ones. I would suggest pulling it out of the pot to get a look at the roots and medium. These like to stay on the damp side, but still need air around the roots. (Not clear in the photo, the mix isn't obviously bad, but it is a good idea to see what is going on farther down. I would use small bark, which fits my watering pattern. If you water less, then sphagnum could work. Or many people on the Board use a semi-hydroponic technique, with inorganic medium. A look at the roots will tell you whether there is a problem brewing or not. But you have a new growth, so this is a good time to repot, get it into an environment that fits YOUR watering pattern and conditions.

Yes, I received the plant 4 days ago, but the brown parts aren't mushy - the browner they are, the firmer they are. This is why I don't think it's rot.

I strongly suspect it just underwatered...

Hi Roberta and thanks for your reply. It turns out that the central roots are a bit rotten, but there are plenty of roots around the outside that are healthy (see pic). A lot of nursery plants seem to be started in moss as seedlings, then potted up into bark, leaving the moss at the centre, which leads to root rot.

You are are correct, that's often the case. The oldest pseudobulbs, and their roots, will tend to die off anyway, the important part is to take care of the new growth. When you repot, if you have enough bigger pseudobulbs (which it appears that you do) you can even just remove that oldest little "seedling" pseudobulb, it isn't going to do much for you or the plant. Then place the oldest part of the plant against the side of the pot, to maximize the space for it to grow. (These tend to march along the rhizome, in one direction, eventually climbing out of the pot. So you want room for maybe 2 years' new growth. After that it will need repotting again.

Ah well, I guess that's what I'll be doing first thing in the morning after my coffee! It's mid-evening here and my eyes are getting a bit tired - I don't want to be chopping healthy roots off.