Oncidium Sharry Baby 'Red Fantasy ' new leaf turned brown
 

Hi OB,

My Oncidium Sharry Baby 'Red Fantasy' new leaf turned brown from new growth.

I noticed similar behavior in my Brassia (Ada) Aurantiaca a few weeks ago. Is this because of over-watering, fertilizing, or something else?

Please advise.

Thanks.

When did you transplant it to that bark? How are you watering? What have your temperatures been?

Hi ES,
Thanks for your reply.

I have repotted it in bark in Oct 2023, I am using kind of self watering with wicking thread but I am not keeping much water since winter started, currently its sitting in my garage east facing window and at night its temperature somewhere around 55ºF from last couple of weeks.

Thanks.

That's too cold for this plant unless the next day is very much warmer. Can you keep it in the house?

Wicking doesn't work with bark. Newer bark is hydrophobic and doesn't wick at all. It will wick when it's older, but there isn't enough surface area on the bark to wick up enough water for most orchids. Wicking tends to work only with potting media that have very small particle sizes.

I think the problem is not enough water. Dying from the center is characteristic of Oncidium new growths when they don't get enough water. In that size bark I would water an Oncidium every 2-3 days. Newer bark retains much less water than older bark. I would pour lots of water through the pot to make sure it gets everywhere.

Fortunately this is a very tough plant that survives less than ideal conditions better than most orchids. Get it warmer and water it more. As temperatures rise it will probably put out more growth.

Hi ES,

Appreciate your reply.

I will move all of them into the house, till it gets more warmer outside. For the last couple of days, it's getting much warmer during the day around 70ºF, but I will move them inside for now.

Thanks again for the suggestion.


Thanks

It also looks to me like it gets water in the crown - the white crystals on the edges of the lower leaves are a good indicator. That can leave a "puddle incubator" for all kinds of pathogens.

This is good advice ES. I did not know about the characteristic of not watering enough = oncidiums going brown from the middle. Which leads me to a question....I posted a few pics a while back of my Onc. Twinkle Pink Profusion. The flowers did not develop well. I was told the plant looks dry as there were some exposed roots. So what I did was add more bark to cover the roots and recently added moss above that.
My questions is, is it ok to have that bark moist/wet? A friend suggested it to allow a slight increase in humidity for the plants, and also to allow for more even drying and air flow. Some of my plants like it, and I have almost done it on all of my oncidium types. My zygo Jumpin jack put out 4 new growths within weeks of adding a layer of moss. You mentioned the white crystals, is it bad to have a ring of moss around the plant? Will that lead to crown rot, or is crown rot when you have water sitting in the leaves and flooding the crown.? In my case the moss is just barely touching/cradling the base of the plant. What do you think? Thank you and sorry for the long question! John

Orchids have widely varying requirements. They can't all be treated the same. Oncidium and Zygopetalum hybrids (and most species) would rather not dry out ever. It's OK to keep them very moist so long as there is plenty of air in the mix. A layer of moss around the base could work well in some conditions.

Zygos aren't easy because they prefer pure water, fresh air, high humidity, high light and (for most but not all) temperatures of 70 F / 21C or below.

Rots in house plants are almost always caused by inadequate growing conditions leading to weak plants. Plants in habitat get rain into the crown. Collar problems in these particular orchids may be caused by water too high in minerals, or by letting the medium dry between watering. Frequent watering rinses out the minerals and minimizes buildup on high points.

Thanks Ray.

It makes sense because as the media looked very damp when I pulled the clear pot.

Do you suggest to repot it or would it work not using self watering and water when it actually needed.


Thanks.

I would not repot until you see it making roots. I would stop using the wick watering and change to pour-through watering with that larger bark.