Fungus??

[jlosaw]

I just noticed this gunk? growing on some aerial roots in my gh. So far not affecting slippers but a vanda and Cattleya that are on mounts or hanging baskets.

Any idea what this is? It feels fuzzy to the touch and does seem to scrape off with a fingernail.




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[Ray]

Looks like smut, a cephalosporum fungus, but I've never seen that on orchids.

I'd try thiomyl.

 

[xiphius]

Interesting...

I would suggest submerging the entire root mass in hydrogen peroxide to try and get rid of it. It's possible that it is not directly affecting the roots (just growing on the surface), but it may start to choke them out if it gets too dense.

 

[myxodex]

I think it is a saprophytic fungus, looks a bit like Alternaria sp. but without a microscope it's impossible to tell. There are a bunch of common fungi that are generally called "black moulds", some of them can be very allergenic and can cause respiratory problems if the spores are inhaled. So if you try Xiphius's suggestion, which is along the lines of what I would do, then work outside or in a well ventilated place or wear a decent face mask. If you have been feeding a lot of organics like seaweed extract, then stop this for a while until the fungus is under control.

 

[Martin2020]

Never trust your water 100% when dealing with orchids.
Add 1/2 or 1 of teaspoon of Dithane M-45 yellow fungicide into 2 liters of water.
Spray it at night to your orchid's bulb roots leaves and into media.
Looks like the water you use is very dirty.
Also apply this treatment to wild orchids freshly picked out from jungle.
Trust me they will rot within 2 days at garden.
Best method is by dipping orchids into a bucket full of Dithane M-45 solution.

 

[jlosaw]

Thanks for the help on this...Doing the peroxide bath now.

Hopefully it clears it up.