Fuzzy white mold growing on bark mix of repotted Phal - Orchid Board

LizHM · #1 05-17-2014, 02:35 PM

Hello,
I am new to the orchid board. I have a problem with a Phal that I repotted 1 month ago into "Phalaenopsis Dark Classic Orchid Mix" from repotme containing "Medium Coconut Husk Chips, Medium Sponge Rock, Medium Stalite , Medium Granite Chips, & Chilean 5 Star Premium Sphagnum Moss . " Now the bark is growing a fuzzy white mold. I am not sure if I should repot this plant again. Previously it was growing in sphagnum moss from the store and the roots were rotting. I removed the rotten roots and replanted it in this bark mix, an a ceramic orchid pot with holes for air circulation. It is growing indoors in an east facing room, with a room temp of 72 degrees and is on a humidity tray. I water it once a week. I also recently got a fan for it to increase air circulation. I read about using physan 20 and have ordered it, but did not receive it yet.

WhiteRabbit · #2 05-17-2014, 08:45 PM

You could pour some 3% hydrogen-peroxide through the media ...

It may be that the media isn't drying sufficiently ...

Optimist · #3 05-17-2014, 08:55 PM

Perhaps contact repotme. They are a very reputable company, and may know what to do.Do you live in a seaside, very humid area? My mom lived in Washington state, and if she left her shoes out, they would get some mold on them.

LizHM · #4 05-19-2014, 07:07 PM

I contacted them and they recommended Physan 20, so I will try it. I am located in Long Island, and we have had a lot of rain lately and the weather is cool, so it doesn't help w the mold.

lotis146 · #5 05-20-2014, 01:02 AM

Not so new to the board but since already posted here I'll refrain from making a new thread about this same topic. I too am having this problem with several of my Orchids - different species, different mediums (Onc. in bark, NEW Phrag. in bark/rock mix, newly repotted Dtps. in moss, Miltoniopsis in bark mix, & more) - even within less than two days of watering. Heck it even seems near instantaneous.

Here in the Midwest we had some warm/hot weather about a week ago then it has cooled off a lot (went from running the A/C to turning the heat back on). My house stays in the 70s year round, perhaps it's more humid than I realize.

As I'm sure Liz is wondering, what kind of hard can/is this doing to the plant? I understand that Physan is a pretty serious chemical. Does it have an odor?

White Rabbit, are you suggesting just pouring HP 3% straight on the medium? Makes sense that maybe it's not drying fast enough but how about receiving Phrag. Olaf Gruss Saturday, watering it that afternoon and by Sunday evening there's mold...?

Thanks, and Thanks Liz for bringing this up. Beat me to it.

King_of_orchid_growing:) · #6 05-20-2014, 01:21 AM

Physan 20 does have an odor. It's hard to describe. The smell is kinda sharp. A cross between diluted bleach and liquid soap.

I don't trust using Physan 20 on plant roots. It may have disastrous results.

I'd rather use this product to sanitize pots and hard surfaces - maybe the potting mix itself, but not on a plant. Just my :two cents:.

The medium may not be drying out fast enough, as was mentioned prior.

Try switching out the mix to something else that dries out a bit faster.

mimigirl · #7 05-20-2014, 05:55 PM

Is the mold only on the growing medium? I am always afraid of mealy bugs.

judith_arquette · #8 05-20-2014, 06:05 PM

I just switched over to the clay "rocks" because of the same issue. Even when I had a fan running continuously the bark would get mouldy. Hopefully this works because idk how much more repotting my poor plants can take. They don't seem to have suffered any ill effects but I'm sure they'd be much happier left in peace...

lotis146 · #9 05-20-2014, 08:46 PM

Not sure about LizHM, the original poster of this thread, but in my case the mold is also in contact with the roots that are exposed on the surface.

Mimigirl, it's definitely mold, not Mealy Bugs.

Interesting Judith. My biggest guess here is that the humidity is probably far higher than I realize it is because I've gotten used to it, and with the added heat, less use of the furnace to blow hot air, this mold is having a good time. If it doesn't harm the plant than I'm not too concerned about it of course if it does, than I am.

I'm sure it's because of the moisture in the medium and it not drying immediately but in my case I don't want the medium to dry up right away then I would be watering ALL the time. What's happening is the mold is growing within 24 hours. I've noticed on my Oncidium Heaven Scent that when the afternoon sunlight hit the medium after i first noticed the mold it sort of thinned it out but it remains present.

What about using clay pebbles say just on the surface...? I'll have to do some digging - literally - to see if the mold is just a surface issue, I presume it is. With my mini Dtps I picked some of the moss away from the surface and crown of the plant and the moss below was not molded.

LizHM · #10 05-22-2014, 12:38 AM

The mold is only on the bark, not on the roots or plant (yet), but I only repotted these a month ago. I have not used the Physan20 yet. Yes, I am concerned about it being toxic to the plants. Repot me recommended diluting it and pouring it over the potting mix.... I just repotted these Phals from sphagnum moss to bark, and was hoping the bark would provide better drainage than the moss. Should I be repotting to the clay pellets / hydroton??

I am thinking it may be due to the room temperature, as I have 2 different phals in moss that are in a warm room which gets to 80 degrees, and they have no mold and are growing healthy roots in sphagnum.

Yet these 2 are in 70 degrees with a fan and growing mold.

My other question is if I have been watering them wrong? I pour water through the bark 2 or 3 times (it goes straight through) and drain the excess water. I have been doing this once a week. It is difficult for me to tell when the bark is dry.