Phalaenopsis with white fungus on old stem and yellowing middle leaf

[erickar]

Hello everyone,

I have had my phalaenopsis orchid for about a 1.5 years but would consider myself still very much a novice. I have had no issues with this plant until recently.

This fall my orchid dropped two lower leaves. This was a little concerning as last year it only dropped one but it started growing a new upper leaf so I assumed everything was okay. I recently moved so I figured it may be under a little stress.

Since it seemed healthy I decided to repot it as I have not done so since getting it and it had really outgrown its old pot. It was originally planted in bark but I've heard that many people plant in sphagnum moss so I thought I would try that out. I repotted it last week in the moss but now there is white fuzz on one of the old stems and one of the middle leaves is starting to yellow. Attached are pictures for clarification.

When the orchid was in the bark I would water it by submerging the pot in water for 5-10 minutes and then letting it drain out. I would do this every week or so and it seemed to love this. It grew beautiful leaves and had flowers from april to august. I tried watering it this way with the moss and noticed that it was still damp days after watering, which may be the cause of the mold? The bark never stayed wet for long. I'm considering switching back to bark.

I also don't know why one of middle leaves is yellowing. When I transplanted I checked for root rot but all the roots looked healthy. Is there anyway to reverse this? I would hate for it lose a third leaf this year. The smaller one underneath is fine so far.

I have also been battling fungus gnats with some of my other house plants. They would crawl around on my orchid but they did not seem to be affecting it in any way. Fortunately I've been able to get rid of most of them now.

Any help would be greatly appreciated!

[Orchid Whisperer]

I think your post may be telling you the cause of the problem. Sphagnum moss.

The moss holds too much moisture unless you are very careful with watering, and watering practices are very different from those used with bark.

I would switch back to bark, which is easy to work with and drains well. The watering practice you described in your 4th paragraph is fine for bark.

However, with moss, the approach needs to be to keep the moss somewhere between dry and slightly damp. This is hard to manage, though not impossible. (For me it is closer to impossible because my plants are outdoors for half the year and subject to soaking rain - too much water).

I'm hoping the yellowing does not progress beyond the lower leaves. I would suggest going back to potting in bark. As you re-pot, consider removing the lower leaves that are yellowing (use a flame-sterilized and cooled sharp knife, such as an X-acto, taking care not to cut into healthy green leaves). I usually re-pot with dry bark, an wait a few days after re-potting before I resume watering.

Good luck! Oh, and BTW, welcome to Orchidboard.

[estación seca]

The mold looks to me as though it is growing on old, dead flower spikes. This kind of white mold grows only on plant parts that are already dead. It has to be moist for it to grow. There are many people growing successfully in moss, but I'm not among them, despite trying a number of times.

[erickar]

Back to bark! I repotted my plant this evening. I'm glad to hear the white mold is nothing to be worried about. I was reading things about scale and mealybugs and I was hoping I didn't have another infestation on my hands. Not sure if the leaf will recover but hopefully the new environment will prevent it from yellowing further. Thanks for your insight!

[silken]

I would consider putting a few holes in the side of the pot too.