yellowing oncidium spike and buds

[Jadeco]

The one and only spike on my oncidium started turning yellow at the tip. The 2 blooms fell off yesterday. Not really sure what's wrong.

The root picture is a little blurry, but you can get the gist of things. The roots are overall healthy, especially the bottom ones peaking out from the pot. Some of the top ones are a dark brown, but not dry.

The leaves are perfectly fine, and you can see the spike in question on the left.

Update: the yellow spread more and some browning appeared. I cut the spike above the third node from the bottom. There is a new "branch" growing from the second node.

[Junebug]

Have there been any changes in the lighting or environment?

[Jadeco]

nope

[Junebug]

I've got some more questions for you. How long have you owned this plant? Did you recently purchase it and if so was it in bloom at the time? Have you ever repotted using fresh media...or checked the roots to see if their healthy? Sorry for all the questions....just trying to narrow things down a bit.

[Jadeco]

I have owned the plant since early February. It was in bloom at the time, with many flowers (9+) and many branches. Since then, it has flowered but maybe 4 at the most without branching out.

The roots look pretty healthy overall. They are all very white, except for a few poking out from the top of the pot. They are a little blackish-brown. I've attached some pictures. Although they are a bit blurry, you can generally tell how they are.

I haven't repotted it yet, but it certainly looks like it needs it. I actually ordered a starter S/H kit from First Rays and plan pot the Oncidium in one of his pots to try it out.

Ever since I cut the spike above the newly forming branch, it seems to be fine.

Another interesting thing is that most of the leaves are a regular green, but some are much lighter than the others.

[Junebug]

This is just a guess, but your plant is probably overdue for a fresh potting. New foliage is typically lighter in color and darkens a little with maturity. I don't have alot of experience with Onc. I have one that was purchased in full bloom in April 2007. It was purchased from a flea market vendor and appeared to be freshly potted so I left it alone. During the next year it grew well, but this April, instead of making spikes it just had new growth so I figured it wasn't going to bloom. The optimum time to repot is when an orchid is producing new growth and the beginning of fresh roots. Like you, I decided to switch mine to S/H. This procedure was done in May and the Onc. took to it very well and is now in full spike. Be cautious to not bury your aerial roots when you switch to S/H as they are likely to rot and be sure to remove any existing mushy dead roots before you begin. I'm not expert on S/H either. My Onc. liked it and my Dendrobiums did not. You are fortunate to have ordered a kit. Be sure to follow the instructions and feel free to pose any questions to the Board. Sometimes conflicting opinions can be a bit bewildering. We've all had success and failures, and what works for some may not work for others. For example: I live in Central Florida, and grow my orchids outdoors and have mild winters and wet summers and a fair share of humidity. My plant selections and opinions may not be suitable for someone living in a primarily dry climate with frigid winters. You're plant looks healthy. Good luck with your S/H endeavor and keep us posted with updates.