Oncidium shriveling up, turning yellow!

[JaimeZX]

Hello - relatively new to orchids and new to this board!

I bought this Oncidium at Lowes about six weeks ago. It has been quite beautiful and I have it on the same shelf with my several Phalaenopsis. I have not repotted it yet because it's mid-bloom and I understand repotting is better done when the flowering is over with.

In the last two weeks or so I've noticed the pseudobulbs starting to shrivel up. Having read that Oncidium likes more water than Phalaenopsis, I've been giving it more. I'm confused though between letting the potting medium dry out between waterings and watering more often.

For example, I watered two days ago and the medium is still moist but the pseudobulbs appear even more shriveled than they were before. Which makes me think maybe there's a root issue and I should repot sooner rather than later.

I looked through this thread:
orchidboard.com/community/pests-and-diseases/90029-yellow-shrivelling-pseudobulbs-oncidium.html

That poster's orchid looks healthier than mine at this point. I think I'll wind up repotting this weekend and checking for rotten roots to cut away.

//BREAK BREAK//

I do not understand how peoples' orchids get snails. They don't travel as spores through the air before finding an orchid... are they just a contagion from the nurseries that breed them or what? Thanks.

[King_of_orchid_growing:)]

The snails people are talking about are called "Bush Snails" or "Orchid Snails", (genus Zonitoides, for example, Zonitoides arboreus or Zonitoides excavatus). These are not your typical garden snails (Cornu aspersum).

Zonitoides arboreus or Zonitoides excavatus are tiny snails. They are difficult to spot without a magnifying glass. These are usually nocturnal. The snails are usually a dark coffee brown in color.

These are common hitchhikers on imported orchids, particularly from South America.


As far as your Oncidium is concerned, I would have recommended repotting it as soon as you got it. Waiting to repot until after the blooms fall off could be disastrous if the orchid stays in bloom for nearly a month. It is growing season, so any damage it sustained can still be salvaged quite easily. It would've been far more problematic if it had been late fall or winter.

[nogreenthumbs]

Originally Posted by King_of_orchid_growing:)

As far as your Oncidium is concerned, I would have recommended repotting it as soon as you got it. Waiting to repot until after the blooms fall off could be disastrous if the orchid stays in bloom for nearly a month. It is growing season, so any damage it sustained can still be salvaged quite easily. It would've been far more problematic if it had been late fall or winter.

Interesting, good to know. How common is bud blast if you repot while in bloom? I assume it varies by species.

[Roberta]

Oncidiums aren't as prone to bud blast with change of contidtions as Phals (the big pseudobulbs pretty much isolate the spike from the environment, may be a factor) However, the flowers don't last as long as Phals anyway... You have new growth climbing out of the pot... repot. I suspect that the shriveled p-bulb is pretty rootless, so it's giving its reserves to the plant. Let the new growth have an optimal environment to grow roots and get water from them, and any sacrifice of blooming will be rewarded next year with blooms that you can take credit for.

[estación seca]

Welcome to the Orchid Board!

The pot is far bigger than I would use for a plant that size. When medium stays wet in the center, and doesn't admit plenty of air, the roots can rot. I suspect this is going on.

You don't say where you live. Is it humid there? dry air? That makes a big difference in what you do.

[JaimeZX]

Okay, thanks much for the inputs!

Repotted tonight. Hopefully I didn't doom this thing by waiting too long. Google images for "shriveled pseudobulb" showed
MUCH less wrinkly ones than I have, and I probably cut away 90% of the roots. I also wound up removing two pseudobulbs,
since the bottom one (right-most in the above pic) and the yellow one were both rotting.



There is some green root growth though. Also, I looked up the snails King mentioned and didn't see anything like that.
There were some tiny white things about the size of a sesame seed that I could crush with my fingernail, but they didn't seem to be snails.
They did seem to be in the bases of both of the pseudobulbs I removed.

Regardless, I sprayed the whole bottom part of the plant with 3% H2O2 and let it sit for a few minutes before drying off.

Last question - as you can see the newest pseudobulb is much higher than the (now) oldest. Maybe an inch?
Which kind of made repotting a challenge because I didn't want to bury the older pseudobulb and that was at odds with
bringing the growing media up to the newer one. Thoughts there?

Thanks again!

[Roberta]

Don't worry about partially burying the old p-bulb. It will just give its energy to the new one, and eventually wither. The new one needs to be potted so that the new roots can reach into the media. This looks good.

Oncidiums do tend to grow somewhat vertically, so it's a challenge to keep them in the media. I tip them forward a little so that the progression of the new growths is at least partially horizontal. In nature, they would like to climb up the tree that they're growing on, so trying to keep them in a pot is unnatural... we do what we can, in the absence of a suitable tree. In a sufficiently humid environment, they love to be mounted... the challenge is to keep them moist enough that way, so we compromise.

[estación seca]

It's been damaged. The newest growth will make another growth, which might not be very large. But each new growth after that should be larger.

[JaimeZX]

Thank you all, again. I potted in a mix of bark and sphagnum.

Not sure y'all's opinion of "Miss Orchid Girl" on Youtube, but per one of her videos - Since the roots don't go very far down yet I put that layer of sphagnum moss on top to re-moisten when it dries out. This should keep the existing roots humid; plus solid soak of the whole pot when the lower bark dries out.

To estación seca - I'm in South Carolina right now. Reasonably humido outside; the A/C does a good job of keeping the house dry though. We're moving to Illinois in July. Maintaining humidity for these orchids could be a challenge; especially in the winter.

[King_of_orchid_growing:)]

Oncidiums usually produce roots from new growth, which is why now is a better time to save the orchid than during the cooler months.

I think most of MissOrchidGirl's advice is pretty good. I don't agree with everything, but I don't think she's giving outright terrible information either. I find that her videos are easy for beginners to grasp.

I hope your Oncidium pulls through. It will be tough the way it is. Warmth, the correct amount of light, high humidity, and good air circulation will put you on the right path. Whether the Oncidium will do anything for you is up to the plant.

Btw, a move from South Carolina to Illinois might be rough on a recovering plant. Just a heads up, don't be surprised if your plant just gives up on you. Who knows though, you could get lucky and the plant may recover regardless of the move. This is something that is difficult to predict with accuracy sometimes.