Is this black fungi and how to treat it?

[KC Kam]

Greetings All,

I need some help here..i am not sure what is this..i highlighted it in the red box...it is spreading to all the roots. I applied some fungicides as well as hydrogen peroxide but i am unable to get rid of it.

I grow some of my orchids in leca...even some leca balls have them.

Can anyone advise on this?

Thanks

[Dorsetman]

Sooty mould by the look of it. No need to panic. I suggest a complete repot, and wash the whole plant, the pot, everything in a disinfectant. You give no personal details which makes it hard to advise properly. - where you live and how you grow enables advice to be better targeted, also affects availability of supplies - what is on sale where you live may be quite different from what I can get, for example.
But if you live in USA or certain other countries ( not in Europe) you should be able to get Physan. Dilute that to 1:1000 for this washing purpose. Then use it for all watering and spraying at say 1:2000. Hygiene is the name of the game.

[KC Kam]

Sooty mould by the look of it. No need to panic. I suggest a complete repot, and wash the whole plant, the pot, everything in a disinfectant. You give no personal details which makes it hard to advise properly. - where you live and how you grow enables advice to be better targeted, also affects availability of supplies - what is on sale where you live may be quite different from what I can get, for example.
But if you live in USA or certain other countries ( not in Europe) you should be able to get Physan. Dilute that to 1:1000 for this washing purpose. Then use it for all watering and spraying at say 1:2000. Hygiene is the name of the game.

Hi Geoff,

I live in Kuala Lumpur, Malaysia. I grew then in a basket with mixture of coconut chips + charcoal. It actual came this way when i bought it...have it for 2 years. I believe rain drops will reach it when it rains heavily during the night too. I repotted it early of this year because i suspect the medium was breaking down...i removed the medium and remain most of the old roots. The sooty mold? Was there before i perform the repot and i am unable to remove all of them therefore i just leave it be. I potted it in LECA and new pot which was shown in the photo.

I realise they kind of dig into the root because after i remove them, the roots doesnt seems to be white anymore.

I cant find any physan here...

Thanks Geoff.

[Dorsetman]

Right, thanks for info. No, if you catch it early it is on the outside of the leaves or whatever, and can be wiped off ; if left, it gets into the plant, especially into the roots because they are covered with a layer ( the white stuff) called velamen which is specially deigned to let stuff ( water) into the plant - so provides a way in for the mould too.
So you ( too) cannot get Physan, Not to worry, there are many equivalents. It is a quaternary ammonium compound, very similar to ones used for disinfecting swimming pools etc. The stuff I buy in UK is sold for disinfecting work surfaces used in professionl kitchens, restaurants etc - but they are all quaternary ammonium compounds, all disinfectants. Use any of them - keep them weak . I think up to 1:500 for really serious work, but normally I use at 1:1000 ( which is an English tea-spoonful in a UK gallon ) or even as weak as 1:5000 .
Best of luck.

[KC Kam]

Hi Geoff,

The Sooty mold appears only in the root area..none from the leave at all. I realise some of the orchids that i bought comes with them from nursery.

I will source for the solution. However, very diluted clorox wont work right?

Thanks Geoff.

[Dorsetman]

This is an illustration of the locality need. Clorox not known in UK ! I discovered something about it via Google, but have no personal knowledge of using anything similar. I believe that something similar is used in orchid propagation, sterilising seed etc., but again, no personal knowledge....

[Sheryl]

I had that black mold/dirt on some roots of a vanda I purchased at a show. This is what Sriram suggested and it worked very well. "I would use a toothbrush and brush it with a mix of mild lemon juice. Could be just mould and dirt".

[KC Kam]

This is an illustration of the locality need. Clorox not known in UK ! I discovered something about it via Google, but have no personal knowledge of using anything similar. I believe that something similar is used in orchid propagation, sterilising seed etc., but again, no personal knowledge....

Hi Geoff,

Noted.

---------- Post Merged at 09:30 AM ----------

I had that black mold/dirt on some roots of a vanda I purchased at a show. This is what Sriram suggested and it worked very well. "I would use a toothbrush and brush it with a mix of mild lemon juice. Could be just mould and dirt".

Hi Sheryl,

I will try this too.

Thank you very much.

[raybark]

The chlorine bleach sold in the US is typically 5%-5.25% sodium hypochlorite. I used it as a general greenhouse disinfectant for years at a 1:128 dilution.

[daenna]

You can use copper oxychloride solution in cleaning the roots. Mix 1 part of copper oxychloride to 3 parts of water.