Not sure what this is...

[camille1585]

I don't think S/H is the culprit here, and personally I think that the pots are already on the large side as it is (though size doesn't matter in S/H). I'm not sure that Kosta understands what S/H is. I agree with his comments, but only if the plants were potted in the traditional way in a bark mix. You don't want S/H to be more airy and dry out faster, or else there's limited wicking, and the pellets must stay moist.

[WhiteRabbit]

I don't grow s/h, but think I may have read that Onc Twinkle tends to not do well that way ???

I do know that I have killed a couple Twinkles - they do seem to like to dry out inbetween waterings grown traditionally, unlike most Onc and Onc alliance I have that seem to like to remain a bit moist.

[Pilot]

Ok I'm just confused now. I have never had issues with sh and these guys are growing fast I'm just running into these browning tips, most prevalent on the old growth.

So should I plant these things higher?

[nenella]

I definitely agree that they are too deeply buried!!!
Pull them out a bit

[Kostas]

I do know what S/H is and the smaller the pellets the moister the plant stays. With plants that like good air circulation on their roots,smaller pellets keep them too wet for too long and problems arise. Even in S/H,pellet size is determined by the needs of the species grown. This one would like it drier and its root system would be able to reach the lower,moister pellets as well and so still satisfy its water needs
I definitely did not advise to repot to a bigger size pot. I only advised bigger diameter pellets in the same pot.

As for the fast growth they show,that is good but still,if this disease is allowed to continue,it will more than catch up with their growth rate. It progresses from the older leafs to the very newest one though a few month period. The sooner you catch it and change the culture to the fungus's dislike,the less time it will take for them to look good again

Pulling them higher is a good start and if you also increase the air circulation of the area they are growing,it may well work out and stop the problem. The spread of the black marks should slow down and stop within a few days if what you do is enough to stop the problem. If it doesnt stop within a week after the change,make more changes towards a better aerated root system that stays drier.

[Leafmite]

Orchid Pests, Orchid Diseases

This orchid society has nice pictures in their disease section and explains what to do for each one. I hope it helps. The othe site that is good is Cloud's Orchids.
Good luck!

[Pilot]

Thank you everyone for your input. I've pulled the plants higher up in the medium and they are practically sitting atop the medium now. Two of the twinkles haven't many roots yet in the medium but there are some. The species plant has an advanced root system already! But it too is affected so I'm guessing it is in fact fungal and it has been treated with Cleary's.

I've removed the infected tissue, soaked it with Cleary's and sprayed it down pretty good with the solution, too.

Do I have to apply multiple treatments? Or just this once?? I'll definitely be leaving this plant dryer at the top. thankfully, I live in a place where that is easily achieved!

[Kostas]

If the cultural conditions are corrected,as you did and are doing,a single good soak with fungicide should suffice to immediately halt the fungus and the good culture will take care of any surviving fungus. If the plant is very valuable to you and dont want any risk of fungal progress at all,you could apply at each watering but,although that will certainly stop the fungus,the plant growth rate will also be affected negatively from the fungicide. It comes as a side effect and can even halt the plant growth for a while.

Oncidium root and grow fine even when kept dry and watered periodically,so leaving them drier,even with a small root system,wont hurt them. If some of the roots reach deep enough to be in moist pellets,no watering is needed even with the roots above being dry for prolonged periods,they will still grow. If no root reaches deep enough,you need to water those every few days,a day after all roots are fully dry. Just make sure the pseudobulbs dont shrink too much. If they do shrink,just water more often but with very good air circulation afterwords.