Black spots and rot on my phal flowers - please help diagnose.
 

One of my favorite phal is has developed black spots and rot. At first I think its a Botrytis, now I am not so dure.

The spots spread very slowly and its not like the typical botrytis picture on the web. It also effect the center of the flower not just the petals. Some of the spot appears on the back of the petals and some on the front.

Growing condition does not seem to support botrytis infection (20-25 degree celcius with 50-70% humidity, airflow is limited during the afternoon but plenty during the morning when the windows is opened. I have grown many phal in this location and none got this problem. The plant condition is very good, supporting 28 giant flowers and still growing leaves and roots at the same time.

I also notice some small insect (1 or 2 at once) hovering around the plant. Not sure what insect it is, but this is not the first time my phal attracts insect in other locations too.

Please help diagnose my plant's problem. This is my favorite plant and I really don't want to lose it because its very rare and hard to replace. Will the same problem develop at the next flowering season? Thanks.

Could the spots be from misting the plant and getting droplets on the flowers?
Are the insects fungus gnats?
Joann

I never mist this particular plant. I only apply water to arial roots and leaves surface using my hand and tissue. No rainwater or other water droplet could touch the flower because its in indoor location far away from open window (about two meter away from window opening). I never open window when raining.

I will definitely check on what fungus gnat is. Does it do harm to plants?

Fungus gnats feed on fungus and decaying matter in old media. Once they finish up the fungus, the larvae start working on the orchid roots.
If you see them flying around, it might be a sign that you should repot. They're hard to get rid of.

Do a quick search on here- there are some great past threads about gnat control.

Will s/h growing method be more resistant to these fungus gnats? I can't repot the plant right now because it is still flowering. wouldn't the larvae be useful in feeping the fungus growth in check?

No, the larvae are not useful for anything. It's just not worth the risk, and they can take over an entire collection really quickly.

With LECA being inert, it wouldn't have the fungus problems that decomposing organic media would- so not as many, if any, gnat problems.

Confirmed. Its a fungus gnat problem. Saw the larvae squirming in the moss and the adult match the picture i saw on the web.

I just bought a carniverous plant and see if i can control the adult. I am also trying to make the yellow sticky trap, but still no clue how to do that.

What do I do with the larvae? I don't have the bacteria solution and don't want to try chemical because my plant is too precious. any advice?