Mold, Fungus, and/or Rot

[cantrell]

Hi, all. I have a mini phal I bought about a year ago. I recently repotted it in lava rock, gave it a little fertilizer, and was pleased to see that it rapidly started growing roots. But yesterday, as I was taking a closer look, I noticed a white fuzz on some of the roots and rock, and when I peeked at the stem, it appears to be rotting (it's turning black; see attached photos).

Can anyone help me identify what's going on? I don't think I've been over-watering. It has been receiving too much sun (hence the dark green), but I don't think that would explain the presence of mold, fungus, and/or rot.

Thanks,
Christian

[Selmo]

Looks like snow mold (ptychogasyer sp.) it usually grows on decaying potting mediim. It usually will not harm living plant tissue, unless it covers large areas, then it can suffocate the tissue by not allowing moisture and air to the tissue. This mold is usually caused by overwatering, which causes the medium to break down faster. How old is the lava rock , or where did you get the lava rock? And ussally the more sun/light an orchid gets pasted optimal, the lighter green or yellow it becomes. Your plant seems to be in the high side of optimal with the dark green and red color. Not the problem. Problem is how much are you watering, how old is the medium you are using, and what kind of air circulation do you have. My suggestion is to wash off mold from plant and roots with a soft toothbrush, being careful not to damage the good tissue, repot in new fresh medium, water after medium has dried some before watering agian, and increase air movement around plants.

[cantrell]

Hi, Selmo. Thanks for the response. The rock is fairly new. I bought it a few months ago from Lowes (a big bag of it), and I repotted the orchid just about a month ago. Last night, I repotted it using a clean pot and new lava rock, and while I had it out, I gave it a good cleaning using hydrogen peroxide. I'll pay closer attention to watering, and I'll see what I can do about increasing air circulation. Maybe a small fan would help.

Best,
Christian