My Oncidium roots are molding, leaves turning yellow

[WaterWorksGS]

Hello all! I am new here and I hope I'm in the right spot. I feel in love with my oncidium orchids that I ordered to sell at my store and kept them all. When I received them over a month ago they need to be re-potted really badly. I re-potted them with hydroton in a 4in net pot. I am using Dyna Bloom 1/4tsp/gal and the Dyna Protekt 1/4tsp/gal together. I water them only when they get dry(1/wk at most).
They are in full bloom now and just the other day I moved out of my indoor greenhouse and I noticed mold on most of the roots and hydroton. I have read that Physan 20 should be used to disinfect everything. I ordered that today however it will not be here until next week A couple of my ladies have leaves that are turning yellow also. I had 3 that still had a couple of buds left to bloom but they fell off. I had them under a 150w HPS for 6hrs a day. That is why I moved them-hoping that they were getting too much light and the new buds dried up. I really do not want to wait until next week for Physan to get here to do something. Any ideas on what I can do now to get rid of the mold and not stress them out to much? Thank you!

[King_of_orchid_growing:)]

Oncs like moderately bright indirect light.

Do you have a pic? It helps people diagnose the problem much faster, and it helps people distinguish other problems you may not be aware of.

I don't have experience with Hydroton in orchid growing. Others do. Your problem is not such an uncommon problem to come across on the OB. Someone with more knowledge of semi-hydroponic methods should answer your questions.

Welcome to the OB.

[Orchid126]

You might try either hydrogen peroxide or household bleach. The hydrogen peroxide you can use practically straight, but you might want to dilute it. The household bleach you can probably use a teaspoon to a quart of water.

[King_of_orchid_growing:)]

Originally Posted by Orchid126

You might try either hydrogen peroxide or household bleach. The hydrogen peroxide you can use practically straight, but you might want to dilute it. The household bleach you can probably use a teaspoon to a quart of water.

Don't put bleach on the plant! Bleach is dangerous! It can kill off the roots of the plant almost instantly! Leaves can get severely damaged depending on the concentration.

Peroxide must be used with caution as well. I don't recommend having the roots touch this either. Leaves are okay.

I think he means using it on the Hydroton.

[Orchid126]

Chlorine Bleach is what they use in swimming pools. I never heard that pool water will kill a plant. One teaspoon to a quart is not lethal, and is nothing compared to the percentage of what is used in a swimming pool.

And as far as hydrogen peroxide is concerned, I saw a greenhouse grower pour directly from the bottle into the center of a phal, hoping to kill off a disease. Hydrogen peroxide is oxogen, after all.

[Orchid126]

WaterWorksGS, bleach is not dangerous in dilution, it will not kill off the roots of your plant instantly, that concentration will not severely damage leaves. Peroxide touching the roots will not damage them either.

Please check out First Ray's site on plant problems:

First Rays' Home Remedies

For the hydrogen peroxide check out "Fungicide", then "Spray" then "Hydrogen Peroxide":

"If your phals look like they're starting to get crown rot, sometimes simply pouring some straight-from-the-drug store hydrogen peroxide on the wound can stop the processs. Just be sure to tilt the plant and drain the crown after about five minutes so it can dry."

Check out "General Purpose Disinfectant" for chlorine bleach:

"Add one ounce of household chlorine bleach to a gallon of water and spray on utensils, benches, even your plant to control a wide variety of pathogens. It even helps to control algae."

This site is the result of some quick research. There is lots more information out on the net about these two products, if you care to do more. Ray has some excellent advice on his site and you can trust him implicitely.

[King_of_orchid_growing:)]

Originally Posted by Orchid126

Chlorine Bleach is what they use in swimming pools. I never heard that pool water will kill a plant. One teaspoon to a quart is not lethal, and is nothing compared to the percentage of what is used in a swimming pool.

Chlorine bleach in moderate concentrations even in pool water is also what irritates many people's eyes. Let's not talk about plants.

People don't normally dunk their plants in pool water anyways. Water from the pool usually gets on plants when the water splashes onto them by which time, a number of chemical reactions and microbial activity factors in.

Bleach can kill cells. Dilution is key and concentration matters! Certain parts of a plant can be sensitive to bleach no matter what the dilution or concentration is that is considered effective for performing as an antiseptic. The kind of orchid also has to be taken into consideration too. Not all orchids will react the same way to certain treatments.

I still stand by not getting bleach on the roots. I will not budge from this statement. Particularly when I speak from my own personal blunders and not secondhand observations (speaking about myself personally here, I'm not accusing anyone of using secondhand info)!

Originally Posted by Orchid126

Hydrogen peroxide is oxygen, after all.

Hydrogen peroxide = H2O2

It's not oxygen.

Oxygen (O2) is a byproduct of the chemical reaction that occurs with H2O2 when it's exposed to the air. The other byproduct is H2O (water).

Hydrogen peroxide does have good antiseptic properties, however, it doesn't discriminate as to what kinds of cells it kills.

edit:Although not quite as potent as bleach, it does kill cells (I didn't dream this up, I had a botany instructor mention this to the entire class during lab as a kind of fun fact). It kind of has a very weak bleaching effect. You can try it out if you like, on your own fingers (I wouldn't do it repeatedly over an extended period of time though).

There was most likely a couple of good reasons why the nurseryman tilted his Phal while applying the hydrogen peroxide to the crown of the plant.

I did say applying H2O2 onto leaves is fine.

I, however, also recommended against it hitting the roots as much as possible.

Now if you're talking about the oxidation process being the thing that makes H2O2 an effective antiseptic, then yeah, but H2O2 is not O2.

[King_of_orchid_growing:)]

I'll offer up a possible alternative.

I've not tried it yet, but have read about it and it's prevalent use in the maintenance of koi ponds.

Try looking up potassium permanganate.

Because, I haven't tried it out yet, I can't give detailed info about it.

The only thing that comes up regarding it's safety in use with disinfecting plants is that it should not be used on Dendrobiums.

[CTB]

Welcome to the Orchid Board, I'd wait for the physan20I have never seen mold on hydroton. You need the good stuff. Did you clean all the spag moss off the roots? That's the only thing that I know that could cause mold.?

[BobInBonita]

When we resort to chemicals, we are purposely choosing to use something that can harm living things. After all, we are trying to kill off the bacteria or fungi that are attacking our orchid.

Bleach, peroxide, and potassium permanganate are all POTENT oxidizers. They will break double bonds in just about any organic molecule they touch. That is how they kill pathogen (or damage healthy tissue).

In terms of oxidizing power, the household peroxide at 3% is the gentlest, Chlorine is a much stronger agent, but at the dilutions you are talking about will usually react so quickly with other organic material (dust, dirt, the media, etc) that it is relatively safe. By memory, permanganate is the strongest oxidizing agent of the three. In laboratory use more protective gear was required to use concentrated permanganate solutions although it was used as an antiseptic (especially veterinary) prior to antibiotics. a side effect is that it will stain whatever it touches purple.

Of the three, I would choose the peroxide. WHile it is working it will bubble. When it is finished it has released oxygen and only water is left.Chlorine, when it reacts will leave chlorides behind. THe permanganate will leave both potassium and manganese salts behind.

If you're worried about fungi, why not use a fungicide designed for plants. Many are commonly available at garden centers