Need help with mold killing my orchid roots!

[greenleaf]

I have a cattleya that I repotted 10 days ago. It had some mild root rot but I was able to clean off all the bad roots and repot it into new bark mix. It still had a sufficient amount of roots left and 5 very nice pbulbs. I watered it a week ago.

Anyways I didn't see the plant for a week and now I got back and I noticed that though the surface is dry, there's tons of water vapor and droplets inside the pot! And mold too! Cobwebby mold and green patches of mold! (It's in a 4" clear plastic pot btw.) I quickly unpotted the plant and noticed mold growing on the roots, and more roots rotting, looking like brown jelly!

Where did the mold come from? I used a newly opened bag of bark from Home depot. At first I did notice some white stuff on the bark but I poured boiling water on the bark as a precaution. What caused the mold? Should I spray with fungicide and what's the best brand of fungicide? What else should I do?

also I live in US near D.C. and humidity is low so I don't know why so much mold...and what I did wrong

thanks for the help!

[Zoi2]

Chances are that your potting media had mold spores in it or you didn't get it all cleaned off the plant when you repotted. I would probably clean the roots with Listerine and repot with another brand of potting mix. How big is your pot? It may be staying too wet if it is much larger than your plant needs.
Joann

[Lagoon]

Sounds like you're media was off from the start. Trash whats in the pot and go get you're money back for the remainder in the bag.

Get some good quality media - cheaper in the long run. I like to get most of my media from an orchid source, this way you get mix it the way you want.

Joann, the pot is 4in. Even in 10 days a good media is not going to go bad like that. You're right the spores were already there.

I would also pick up some physan20 - always great to have around.

Welcome to the board Greenleaf

[trdyl]

Welcome to OB!

You'll get a lot better quailty mix from a orchid nursery than you will from Home Depot.

[King_of_orchid_growing:)]

Here's the thing about fungus.

I'm by no means a mycologist or a fungus expert, but this is what I've learned in botany so far...

The part of the fungus that you see as the green fuzz, is only the fruiting body.

The webbing is the mycelium made up of the hyphae. This is the actual fungus that produces the fruiting body. It's very difficult to detect with the unaided eye. That's why you may have thought your orchid roots were clear of fungus, when they may not have been.

Fungal spores may also come along for the ride on the media too.

Try sanitizing your pot and the potting media before using.

As for the orchid roots, try Listerine as someone had mentioned.

[greenleaf]

Thanks for the info ...just curious...do I use listerine straight from the bottle? Should I spray Listerine on the roots, or soak the roots in it, or just water the plant with it? I got the blue liquid version of Listerine, hope that's the right kind.

can't find any physan nearby so I think I'll need to order it...also, I bought 2 kinds of fungicides, one is copper based and another is sulfur based. Which one should I use, or should I use neither? Because I'm scared of adding stuff to my orchid roots...

thanks!!

[Zoi2]

As far as the Listerine goes, the basic brown is the best. The other "colors" have additives that probably will not do any good for a plant.
Just put some Listerine in a small spray bottle and spray the roots. I usually let the plant sit for 5-10 minutes after spraying before I repot.
Joann

[Cello09]

Greenleaf - I've had a similar problem. I bought 3 phals, potted in far too much, far too saturated sphag. I cleaned off the rotted roots and repotted them in my favorite bark mix... and now, a few weeks later, I can't keep this white mold from growing on them! I water just a little, once a week, and don't over-pack the bark so some air still gets to the roots. Yet about every 48 hours, I find more white mold on the roots and have to clean them with fungicide and use all new potting mix. Many are down to very few or no roots. I'm hesitant to pot in sphag to regrow roots because of the mold tendency.

Thoughts would be very greatly appreciated

[Cello09]

Oh, and as far as type of fungicide - I found an organic kind, called "EcoSmart." Got it at Home Depot and it's had no bad effects on the roots.

[Undergrounder]

greenleaf - You said you just repotted it? It sounds to me like the roots are dying after the stress of repotting and the mold is attacking afterwards. All the fungacides in the world won't fix the problem, you just need to sanitise it as best you can as others have suggested and then pot it up in fresh mix and leave it there. The new roots that grow will be able to resist the rot much better.

The cobwebby stuff is a cobweb mold, the green stuff is a Trichoderma mold (or the spores thereof), separate things. They're both common 'molds' but these aren't the cause of the rot, just the symptoms of bark that is wet and rotting.

cello09 - If you're constantly getting mold problems, check your general culture conditions.. make sure there is sufficient air movement and good light first. You shouldn't (if possible) fix mold problems by witholding water, it only dehydrates the plant, kills roots and adds to the problem.

Also, check the quality of the sphag you use.. Use good quality, fresh, NZ export grade sphagnum moss and never ever have mold problems in my sphag. Good quality, fresh sphag is naturally acidic, which actually inhibits mold growth. It was used as a wound dressing during the first world war because it keeps wounds clean and free of infection. By contrast the stuff you buy in garden centres is 90% of the time horrible, mushy, decayed, third-rate stuff designed only for decorating handing baskets. And yes i used to get vicious mold growth in it when i used to use it.