White mold on bark chips..... - Orchid Board

Tetra73 · #1 10-15-2016, 06:56 PM

I am pretty sure I did something wrong. First, I have lucks with 3 of my mini phalas and they have bloomed twice for the 2 years I have them. They were in my terrarium and being air mounted with sphagnum moss ONLY. Never had issues with mold or anything else. They do dry quickly too.

With the dendrobium I got 7 days ago, I decided to put it in a very ventilated clear, plastic basket and potted it with some Better Gro orchid barks. They are kind of spongy too.hhhhmmm.. I have moved all of my plants to my newly built grow tent. The humidity is pretty consistent from 75% to 90+%. I heavily mist it daily morning. Last night I discovered a small snail and couple of spider mites on my dendrobium. This afternoon, I decided to remove some barks to check to see if the root system has any damages. The dendrobium has been potted 7 days ago.

Behold, all I saw was snowy white mold. At that point, I decided to repot it again using sphagnum moss ONLY since I have lucks with them with my phalas. It turned out the mold was only on couple of bark chips close to the center of the plant, FORTUNATELY. The roots are fine.

At this point, I am not sure if my bark chips are bad or maybe they aren't able to dry quickly enough to allow mold to develop??? Maybe because I have my orchids in my grow tent with high humidity and with frequent heavy misting and watering?

Also, couple of bark chips have some slimy substance on them.

This was how they were mounted. Now, I replaced all the bark chips with sphagnum moss ONLY and filled it only up to half way. Of course, in the process of repotting it, I disinfected both dendrobium and cattleya with hydrogen peroxide. Is a newbie mistake...to have not disinfecting outside plants.

Cattleya and Dendrobium by vracing, on Flickr

Tetra73 · #2 10-15-2016, 09:01 PM

I did some digging around. It appears to be a known issue with white mold growing on barks. Love to know anyone is using barks without having mold issue. Also, does sterling them work (such as putting them in a microwave oven or even boiling them first).

LexyBoy · #3 10-16-2016, 03:40 AM

Afraid I can't give any orchid-specific advice, but I will say that mould in itself is not a danger to your plants - but it could be symptomatic of a mix which is retaining moisture too long.

People often think they've lost plants to fungus or rot, when the reality in most cases is that the plant was killed by culture (eg root asphyxiation or cold) and fungus has since grown on the dead or dying tissue. Certainly, a fungus which is consuming bark chips (saprophytic) is not going to be pathogenic towards a living orchid. Saprophytic fungi in the medium will break it down however - I'm not sure that sterilising it will help with this (since there are spores everywhere) but might delay things a bit.

Tetra73 · #4 10-16-2016, 10:45 AM

Quote:

Originally Posted by LexyBoy

Afraid I can't give any orchid-specific advice, but I will say that mould in itself is not a danger to your plants - but it could be symptomatic of a mix which is retaining moisture too long.

People often think they've lost plants to fungus or rot, when the reality in most cases is that the plant was killed by culture (eg root asphyxiation or cold) and fungus has since grown on the dead or dying tissue. Certainly, a fungus which is consuming bark chips (saprophytic) is not going to be pathogenic towards a living orchid. Saprophytic fungi in the medium will break it down however - I'm not sure that sterilising it will help with this (since there are spores everywhere) but might delay things a bit.

I came up across this particular bark while googling the subject....Sequoia bark. It is supposed to be mold resistance. Any idea what it is and where to get it?

Thanks...

estación seca · #5 10-16-2016, 03:47 PM

I agree that keeping bark wet leads to mold, the mold itself does not hurt the plant, but being too wet hurts the plant.

Some terrarium plants need to stay moist to wet, but not most Dendrobiums. I would let that one get almost dry before you water again. I don't think misting a potted orchid every day is a good idea, unless it prefers wet conditions.

Also, it might be better to use a much smaller pot in such a humid environment. Too-large pots stay wet too long. Most Dens do better in the smallest pot that fits the roots, plus room for 1-2 years' growth. For your Den I would use a pot about 25% the size of the one you used

Tetra73 · #6 10-16-2016, 04:15 PM

Quote:

Originally Posted by estación seca

I agree that keeping bark wet leads to mold, the mold itself does not hurt the plant, but being too wet hurts the plant.

Some terrarium plants need to stay moist to wet, but not most Dendrobiums. I would let that one get almost dry before you water again. I don't think misting a potted orchid every day is a good idea, unless it prefers wet conditions.

Also, it might be better to use a much smaller pot in such a humid environment. Too-large pots stay wet too long. Most Dens do better in the smallest pot that fits the roots, plus room for 1-2 years' growth. For your Den I would use a pot about 25% the size of the one you used

Thanks. Well, at the moment, I have some sphagnum moss in the basket and only filling up about 1/4 of the space. The entire root system is being loosely tied down by a garden wire. The moss are just resting and surrounding the roots. They aren't compacted. Is getting air flow. My intend is to ensure the root system gets dry up by the next morning so that I can mist them again the next day.

Here is the thing...the size of the pot won't matter because the roots would out grow from the opening slots. It seems that the conventional way to pot and mount orchids won't work that well when the environment (a close one) is closely resembling to a rain forest. I made the mistake in using barks in a close system with high, constant humidity. And air flow isn't huge but enough to dry out my air mounted Phals.

Leafmite · #7 10-16-2016, 06:09 PM

I use red lava rock/basket pots to allow maximum air flow. I have not had any issues with mold.

Roberta · #8 10-17-2016, 12:08 AM

Mold in the bark may or may not harm the orchid, but it may cause the the bark to break down faster (or perhaps be the effect of bark breaking down due to something else) Especially if you see it before you pot, I would suggest not using it. Bark breaks down fast enough without starting with some that is already on the way out. (and it may be harboring other nasties)

I recently dumped a large bag of bark into the compost pile that had mold growing in it - it looked like it had been packed wet, and along with the mold, the bark chips themselves were starting to be mushy. Unfortunately I had not saved the receipt, or would have returned it to the store.

Tetra73 · #9 10-17-2016, 12:12 AM

Quote:

Originally Posted by Roberta

Mold in the bark may or may not harm the orchid, but it may cause the the bark to break down faster (or perhaps be the effect of bark breaking down due to something else) Especially if you see it before you pot, I would suggest not using it. Bark breaks down fast enough without starting with some that is already on the way out. (and it may be harboring other nasties)

I agree. These Better Gro barks are kind of soft to begin with. It was kind of moist too when I got it. If I need to use barks in the future, I may need to order some better ones and shop around more and maybe paying 2x as much.

Roberta · #10 10-17-2016, 12:20 AM

Quote:

Originally Posted by Tetra73

I agree. These Better Gro barks are kind of soft to begin with. It was kind of moist too when I got it. If I need to use barks in the future, I may need to order some better ones and shop around more and maybe paying 2x as much.

Even at twice the price, bark is a lot cheaper than orchids... Even the most expensive is a relatively small part of the cost of the hobby (addiction??) And time has a value too... getting better bark that you don't have to replace in a year is worth it...