My Oncidium roots are molding, leaves turning yellow
 

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:biggrin: 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!

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. :)

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.

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.

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.

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)!

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.

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.

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.?

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

Good to know. I didn't know that. Thank you. :)

Phyton 27 is one of those fungicides.

I re-read this, and feel I have to make an edit, especially after reading the following:

edit: Peroxide is not as potent as bleach.

That was the point I wanted to get at.

So yes, "BobInBonita" is correct in his descriptions...

:Tup: :agree:

Regardless of what you decide to do with the Physan 20 or peroxide, I would recommend better air flow in your growing environment. This should help quite a bit. I've not had good experiences with the indoor greenhouses...they are great for improving humidity but do not allow for much airflow. Maybe try a small clip fan to circulate the air a little better.

If you get a fan, you may need to up your watering schedule to 2x a week, as the plants may dry out a little faster with better air flow.

Hope this helps!

You are making it sound as though I advised WaterWorksGS to pour straight chlorine bleach onto his roots. I did not. I suggested a teaspoon to a quart. This comes out to four teaspoons to a gallon, probably even less than the one ounce to a gallon that FirstRay's site suggests.

And H202 is half oxygen. It isn't a by-productof the combination, but an integral part of the orginal formula--two molecules of hydrogen and two molecules of oxygen=hydrogen peroxide. You make it sound like it's poison.

You went into a state of panic without giving attention to what I was actually suggesting.

Thank you all for your great advice you have given me. I used 1 part peroxide to 1 part water to the roots on the one that looks the worse, just as a trail to see what happens. I think I may take CTS's advice and wait until Physan gets here to use on the rest. I will give you all an update soon, thanks again :)

You need not have bothered diluting the hydrogen peroxide. The 3% stuff sold at the store will not damage the plant at all. In fact, some growers pour it through potting media in order to provide extra oxygen to the plants' roots (2H2O2 → 2H2O + O2, as King mentioned). Alan Koch of Gold Country Orchids told me he "buys it by the pallet load". There are even products on the market for that specifically, and they're just hydrogen peroxide, so why pay extra. (And if you pot your plants up correctly, air flow is not an issue, anyway.)

Before "discovering" Physan, I drenched my greenhouse regularly with liquid chlorine bleach diluted at one ounce per gallon, and never saw any problems.

In my opinion, we have all taken a narrow thought and applied it broadly. Everyone is correct.

Good growing conditions obviate the need for most, if not all, treatment.

If treatment is needed, focusing on the thing that needs to be addressed is best. A specific (targeted) fungicide for a fungal problem, etc.

Non-specific agents (like oxidizers) attack all organic materials. Dilution and contact time is key. Just because they will break ANY double bond they contact does not mean they should never be used. Their very strength is what sometimes makes them safe.

Chlorine at low dilution is perfectly safe, at high dilution it is toxic. I drink and frequently water with chlorinated drinking water. Straight bleach will kill any orchid submerged. Dilution is key. Chlorine is "used" when it reacts and breaks a double bond. Because a single cell fungus presents more surface area than an orchid root, most of the destructive action is on the smaller particles (with high surface area to mass ratios). Poured through media, most dilute chlorine is used before it has a chance to damage the root.

Peroxide at 3% is pretty darn safe (I would wash my hands in it without a second thought), but I have personally been seriously blistered (instantly) by accidental contact with industrial 30% peroxide. Many bacteria have a peroxidase enzyme that breaks down peroxide instantly (the fizz when it bubbles).

Again, everyone is correct, and I apologize if my narrow comments were interpreted too broadly. I did NOT mean it as an indictment of their growing style or chemical use. I promise to try to be more clear in any future posts.

Just yesterday I soaked my ladies in 2tsp:1gal Physan 20 and water. I also sprayed them with it also. This is what they look like today. They don't look so good but I don't think any of them are doomed yet...i hope. I'm not sure if they have multiple diseases, looks like it:(??

Sounds like you are doing all the right things. Now it's up to time. Be consistent in your care, and they should be blooming in no time. I remember you repotted to hydroton, but don't remember what they were in originally. If it was a change in media, there may be a temporary slip before the bounce-back. It's not as significant with a LECA product, if they were in bark the media might be a bit high on the PB.

Best of luck and keep us posted.

It has been a almost a month since I first posted. The roots and fungus problem seems to be better. I still have 2 of my ladies that are not doing so good. The pbulbs on them are wrinkling and some of the leaves are turning yellow. They are in S/H and with that it needs to be watered almost daily and I give the top a mist 1-2 times daily. I'm not sure if that is too much but the hydroton and roots seems to be rather dry when I check on them in the morning. They never sit in water it drains out. My humidity here is 35-45%. I tried letting them sit in water for 24hrs and it didn't do anything to help the shriveling. Any help would be appreciated as to what I'm doing wrong or not doing???

In your original post you say that the orchids are potted in Hydroton in a net pot, which I can see in the pictures. To clarify, this is not the same as potting them in S/H. S/H allows for a reservoir of water to remain in the pot at all times to keep the medium moist. When you water in your current set up, it's really not that different than having potted them in bark...the only difference being the Hydroton won't break down like bark would.

Also, keep in mind that the areas of the medium that you can see will always be drier than the core (i.e., what's underneath what you're looking at). Onc's like to dry out some between each watering, so watering daily (even with Hydroton) might be considered overwatering.

To give you an idea of what I've done with a few catts: I have a few catts in regular clay pots potted in Hydroton and I water them as if they were in bark. This translates to 1-2x a week in the winter, 3-4x a week in the spring (it gets hot in Dallas very early) and almost daily in the summer when the temps really start to rise.

I am not an expert by any means, so maybe I'm missing something. Hopefully more people will chime in with advice.

Good luck!

I repot oncidium types into hydroton as a potting medium when I get them. I have found….
It usually takes a while for them to adapt to the change and the original roots eventually die off as new ones replace them (just because they look like they’re not growing doesn’t mean they’re not working). They seem to sulk for quite a while until enough new growths and roots develop.

I use clear plastic pots and even though the hydroton looks dry I can usually see condensation down inside. If you are using net pots you will have to water more frequently.

The outmost leaves on the existing ‘bulbs will turn yellow and drop off as the plant puts out new growths ( I see a new one in one of your pics.) They may also be reacting to the change in conditions.

Once the existing bulbs shrivel they usually don’t plump up all the way again. It’s OK, the new ones should be nice and plump
You plants look nice. You might send a pic of the whole plant.
　

Maureen

If the plants were bare root, I would suggest cinnamon. I agree with the week Hydrogen peroxide. I know a man who adds a little to his watering can on a regular basis, ever since his daughter was cured of cancer by receiving injections of it.