Mold, mold mold! It keeps reappearing! I'm not panicking… yet!

[donguri]

Hi everyone!

I’m quite new here. My history of orchids goes back a mere one year, as of yet. My orchid roommates – those involved – and I have successfully combatted black root rot, a slight infestation of meelybugs, mmm, what else? Not much really, a moving to a brighter location maybe, but that actually was an improvement. Things have been going pretty smooth so far.

…But now… I bought two lovely red jewels, namely Burrageara Nelly Isler and Horweara Lava Burst through a website, and one tiny Phalaenopsis in a flower shop. I inspected them more thoroughly when I got them home and in all 3 cases I identified fuzzy white-gray mold between the roots just below the surface. When I say mold, I mean those really small white-gray hairlike cobwebby formations that smell like mold (that’s the kind of wet cellar smell – this gives me some ideas: Wet cellar = wet, cold, dark, no aeration. This is what I have to solve.)

I decided to repot them, and needless to say, directly around the crown base they were all tightly packed in old sphagnum moss below the surface layer of bark – except for the teeny-tiny one, which had only the moss media, quite nasty, in a very very small pot. Although finding old moss and hence some squishy roots in the middle is not unusual with newly bought orchids, the strong precene of mold was really alarming. I disinfected them with hydrogen-peroxide, repotted them into more spacious media (mainly fresh bark, just a speck of fresh sphagnum here and there), punched ventilation holes in the sides of their pots. Could have been the end of story, everyone lived happily ever after, yaddayadda. Except it wasn’t so.

I have had them for 3 weeks now and the friggin’ mold just keeps reappearing. I did not want to repot and disturb them again so soon (although I’m beginning to consider it), so I poured some hydrogen-peroxide (as if watering) on the roots through the media, then I got some cinnamon oil and (diluted in water about 1% oil, 99% water, more or less). The mold was gone … for a few days.
How does it keep reappearing !?!
My room temperature may have something to do with it. In these past weeks it has been mostly around or slightly (=1-2°) below 20° Celsius. Not very high. This could be one of the factors.

The orchids are thriving, but they are struggling, their bulbs (resembling oncidiums’) are wrinkly (will wrinkled bulbs ever un-wrinkle again if healthy? I bought them wrinkly.) The mold keeps reappearing, and I can see the plants are suffering. For one, one of them (the Burrageara Nelly Isler) dropped all its flowers, although the mold is less obvious – but it had fewer roots. The other one, which seemed to have a more extensive root system (the Horweara Lava Burst) looks okay, still has its flowers on, but the mold! it’s more obvious (and smellbvious). The phal, well that one is a little older – about a month – with hardly any roots left. Has a one flower stalk that I kept as a balancing aid, because the remaining roots wouldn’t be able to keep it upright. It strives, but there’s no developement, (okay, one month can be a short time, but) its leaves are slooowly getting more and more wrinkly. This one has been repotted twice (bark), had taken a hydrogen-peroxide root bath, and a dry spell for almost 3-4 days now. It doesn’t look good. I can’t see to the roots, what few are left of them. I’ll water it today. Alternatively, I’m thinking about mounting this one on a corkwood block with some sphagnum to grow new roots. It would dry out a lot faster, but would have to get on a more frequent watering schedule as well (daily instead of weekly). Do you think that’s a good idea? Drying out would discourage mold growth and I could also freely inspect the roots, but would it work for this Phalaenopsis?

How will I get rid of the mold without accidentally getting rid of these tender orchids?
It is quite possible I’m doing something wrong, or the mould wouldn’t reappear all the time. Or maybe it needs several treatments. Should I disturb the orchids to expose the roots again to see the damage and repot?

Let’s see what more specifics could be involved:

Orchids involved: Burrageara Nelly Isler, Horweara Lava Burst, Mini Phalaenopsis hybrid.

Room temperature: mostly 18-24°C

Humidity tray: Yes, each. This in fact could be a bad idea as mold likes humidity…

Aeration: Roof window’s slightly open all day. Good air movement at that spot, actually in the rest of the room too. They are close to the window, but this could also mean slightly lower temperatures…

Light: reasonably good. Below South-Western roof window, longest period of light per day, not directly, but in slight shade, no sunspots, but rather reflected light … okay, that’s less heat. Lighting may be a bit inadequate then. However, they did worse in the other (North-Western) bigger window, where air movement was less (because of difficulty opening that window: if I open it, it lets in too much air (windy) = draft).

Watering: I usually water my orchids once a week, but check on them every day before and after work, or at least every day once. Most of the caring is done on a weekend day. Watering is administered two ways: by careful soaking of the media in the pot for a while, with no water reaching the crown, or alternately, from above, in the sink, generously, but also very carefully about the crown. Depends on how dry the medium is – soaking is more efficient, but leaves the media wet for a longer period.

Attention given: I check them frequently and try to take good, gentle care of them. Hopefully.

Other orchids: all doing very well so far. Temperature and general conditions are just about the same as for the moldy ones, yet no damage. They’re lovely, new leaf and root growth, no appearant problems. Lots of joy.

Thank you so much for reading this loooong case report.

If you have the time, kindness and experience, please leave me a few suggestions.

How does mold reappear if the roots been disinfected? Maybe I did it improperly? I watered them right after repotting. Should I not have done that? They looked thirsty, but maybe their roots just were exhausted and water did not help like that. Should I remove them from their humidity tray for a while? (Tray: pot rests on clay pellets, water amidst the clay pellets does not reach the roots.) I can only raise day temperature if I close the window, which means less air movement, but still some. Should I change that? What can I do to provide them the right conditions to battle this mold? Do Nelly Isler and Lava Burst need different kind of care than what I’ve been giving them? Oh how do I get rid of the mold problem?

Thank you for your kind attention!

donguri