Black sticky gunk on phal leaf - Orchid Board

Maru777 · #1 10-17-2020, 01:46 PM

Hello everyone,

I was watering my orchids today and noticed on one of my phals that there was this black soot. I wish I had taken a picture immediately but I initially I thought it might just be dirty and tried to wash it. But the more I thought about it the more I think it’s not just that. I took some picture after I tried to wash it, it was pretty sticky and black. The leaf underneath all that gunk seems to be healthy and the plant is growing just fine, both roots and leaves. I could not even clean it all up - thinking of using a bit of soap on it. None of the other orchids on this shelf have any of this on them so it’s not something that the wind blew on them and they are on a screened porch so it can’t be that something spilled on just this one. Does anyone know what this is and should I take more drastic measures than just washing it?

Paphluvr · #2 10-18-2020, 01:05 AM

Sorry, Maru777, I can't tell from your photo exactly what you're talking about. Can you import your photo into an editor and circle or point to exactly what it is you're concerned about and then repost? I think that would help in giving you an answer.

SouthPark · #3 10-18-2020, 01:08 AM

Possibly plant sap or some people call it 'honeydew' or something. Some orchids will exude sap, especially during times of flowering - budding, spiking etc.

Tango · #4 10-18-2020, 06:02 AM

Hi,
My Phals are regularly infested by scale bugs (there is a big ficus completely infested in my street, I guess they come somehow from there) and the first stage of the problem is leaves covered in tiny little sweet sticky droplets. If you do nothing, the insects get big and by then the sticky sap is covered in black mold. I regularly spray them with soapy water (mild soap!!!) and it's gone.
Hope it helps.
Tango

SouthPark · #5 10-18-2020, 06:16 AM

True! I was too busy typing plant sap, and tango correctly mentioned the extra bits ........ the mold and/or mildew or something then grows on the sap ---- to cause the dark/black coloured look. Removing it with that soap - and allowing leaves to dry with nice nice gentle air-flow will be good for sure.