oncidium with browning pseudobulbs?

[jayayay]

Hi, I recently bought an oncidium from Lowes a few weeks ago. It looked completely okay when I first got it. I then repotted it a few days later with an orchid bark mix which caused some of the leaves to yellow a bit. I'm pretty sure that's normal after a repotting though, and I only really had one leaf completely fall off.

Now though, about two weeks later I have some of the pseudobulbs turning a brownish color. (this has also happened with all my previous orchids). The bulbs feel slightly softer than the other okay ones. I did just water the orchid on Friday and the previous time was back when I first repotted it. Am I just overwatering it?

I did repot the orchid again today after cutting off the brown bulbs and dead roots. the cut edges also got some cinnamon put on them.

[Ray]

A photo or two would really help, but it does sound like something in your culture is allowing, if not causing and infection.

[jayayay]

Here it is next to one of the normal bulbs.

[Ray]

What is the potting medium? That looks like a rot starting at the base, alright.

[jayayay]

It's bark. Like I said, I may have watered it again too soon since I'm used to my phalaenopsis.

[Ray]

Water does not cause rot.

If the potting medium holds a lot of water between the particles, it can suffocate the roots, which die, then rot.

If the plant is potted too deeply, however, water sitting in close proximity to the rhizome can be a great "incubator" for pathogens.

The fact that all of your plants have been affected says that you either have a pathogen in your environment that easily infects your plants, or your watering technique is spreading them.

Do you soak the plants in a common bath or reuse the water, by any chance?

[Roberta]

These actually like to stay wetter than a Phal. But if the bark is broken down (very likely) it is airless and may harbor bacterial and/or fungal pathogens as well. Fresh small bark will give it the moisture it needs, but also the air that the roots need, and a clean environment. When repotting, shake off the old medium that comes off easily, rinse under running water. If bark is stuck to roots, don't destroy them trying to remove it, wont hurt if you leave those stuck-on bits.

[jayayay]

I did plant it a little deep on the first repotting, so that may have caused it. I don't soak or reuse water when watering. I just water it for a minute or two while everything continuously drains out, then put it back in the decorative pot. Would it be better to leave it out of the pot so it gets more air?

I'll get a different bark to see if it stops. Should I be worried about getting something for the rotting?

[Ray]

Personally, I'd take one of two routes, seeking the stop the problem:

1) Water everything heavily with Concentric Ag Garden Solution @ 3 tablespoons/gallon and mist the plant with that occasionally during the day. It is a formulation with beneficial bacteria and fungi that kill pathogens and prevent them from returning, with the added bonus of stimulating growth.

Or...

2) Treat the plants with Cleary's 3336 (generic: thiomyl), a systemic fungicide, and spray the plants, pots and area with Physan, a topical disinfectant.

Either technique will likely take care of it. Do not combine them, as both components of the second treatment method will kill the beneficial critters in the first.

[jayayay]

Thanks for the suggestions. The rotting doesn't look like its spread onto the remaining bulbs so far. I ordered some thiomyl and physan and they should be here on Saturday. Can you give me some intructions on how to treat it. Like, do I spray the whole orchid with the thiomyl solution or just the roots and bulbs. Should I let the orchid dry before repotting, and how many times should I treat it?

I also ordered a kelp fertilizer to promote root growth. Can I use that with the thiomyl, or should I wait a few waterings until it's rinsed out?