Sick Oncidium Peacock?

[Fran20]

Not sure what's happened to this plant. It bloomed in Sept. In mid-Nov. it was growing a new lead and looked healthy. (Photo1) At the end of Jan. pseudobulb started to shrivel even with regular watering schedule. Past week, leaves turned yellow. (photo2). Unpotted today and yellowed leaves fell off. I removed predominantly sphagnum moss plug and surrounding media made of sphag and bark. No pests observed. Please tell me what you see as far as condition of roots or any signs of disease. I was thinking of repotting in slotted plastic 4"pot with lava rock. What should I do now? Your advice is very much needed and always appreciated!

[aliceinwl]

I have a few very similar plants that I’ve acquired as NoIDs. Mine failed to thrive until I switched it from a pot on the ground to a shade cloth lined vanda basket filled with small grade bark that I hung. When potted on the ground, it just would not grow roots into the substrate.

Based on what I’ve seen with mine, they like to stay moist but not wet with a well aerated root zone. I bought an established Oncidium sauvis potted in coarse granite so I imagine scoria would work too.

Here’s one of mine potted up. It was pretty much rootless after 2 years of me not getting things right. But, after a year in the basket it pushed lots of roots and growth and rebloomed for the first time.

[SouthPark]

Fran - the new growth still looks good, and some white colour (and firm looking) portions still look quite ok.

Could the issue possibly be due to the loose spaghnum pieces scattered through-out the bark media, creating bundles of water around some sections of roots, and drowning?

Also, if too soggy for a lengthy amount of time, fungal or bacterial activity can start up.

You could allow the roots to dry a bit first, and then pot into just bark, or just scoria. If the bottom of the pot doesn't have any holes, for extra drainage, then one thing to try is to put holes down the bottom - or bigger ones. I assume there are holes already.

Give the plant some nice warm growing spot and some nice gentle air-movement, and medium light, and good drainage. It can pull through nicely.

[Fran20]

Thanks, Aliceinwl and SouthPark, for your valuable advice! I have noticed that this plant demands more aeration than my other oncidiums which are water hogs. I got rid of the sphagnum moss and will use scoria in a very well-ventilated pot and hope for the best. Thanks once again!

[Ray]

Originally Posted by Fran20

Thanks, Aliceinwl and SouthPark, for your valuable advice! I have noticed that this plant demands more aeration than my other oncidiums which are water hogs. I got rid of the sphagnum moss and will use scoria in a very well-ventilated pot and hope for the best. Thanks once again!

“Water hogs” and degree of aeration are not mutually exclusive!

[Fran20]

Originally Posted by Ray

“Water hogs” and degree of aeration are not mutually exclusive!

Agreed. I used the wrong term. What I meant was it's been my observation that this plant likes to get drier than my other oncidiums that seem to prefer more moisture.

[SouthPark]

Hi Fran! If there are no nasties in the growing environment (pathogens etc), then the oncidium (like many orchids) could handle very wet roots --- continually wet roots providing that the water around the roots remain adequately oxygenated.

If media pieces such as scoria are chosen with suitable size (not too small as to cause water-logging and long-time super-watery conditions in the medium) in a good drainage pot, then a growing area with adequate air-movement (not still air) and good temperature and lighting conditions can allow the oncidium to have moist roots all or most of the time.

I only occasionally allow for a dry-out ...... every once in a while, just for purposes of controlling a few unwanted things (either on the roots and/or in the media). This isn't to say that it's absolutely necessary for occasional dry-outs. It can just be done in case there are possibly beneficial reasons to do it, like making it hard for some unwanted things to start up or build up in the pot, or keeping certain unwanted situations under control.

[Fran20]

Hi SouthPark,
Your points are well-taken. Maintaining adequate air movement in warm weather presents no problem for me because I simply leave all the windows open. My biggest challenge is getting adequate air movement indoors in wintertime. When outside temps are freezing, it's not feasible for me to leave a fan running since my growing area and my living space are essentially the same.

[Ray]

Air movement around the plant is less critical than air movement around the roots, and that is controlled by the openness of the medium as much as anything else.