Green/white mold on phalaenopsis roots - Orchid Board

Cloudmaker · #1 02-08-2021, 11:53 AM

Hi everyone,
I have a problem with 2 orchids. Everything started when i noticed greenish/white'ish spots inside the pot. I couldnt have overwatered them because I water only when they are completely dry, checking freequently, etc. Plus the pots were large enough to let air through. My sister told me that maybe the substrate was moldy when I bought it, because this is frequent issue. She suggested repotting and pouring the substrate over with boiling water, which i did. She also suggested to spray hydrogen peroxide 3percent on the roots, which i did as well. And of the orchids go to the new pots and new media. After couple of days here is the moldy spots again, both on the substrate and roots... I mean how and why? What am i doing wrong? What should i do.. i have no more substrate and pots to replant and everything is closed due to pandemic... Eshoping sucks at this point. Any thoughts?

camille1585 · #2 02-22-2021, 05:43 AM

Welcome to Orchidboard! Sorry that no one has tried to help you with your questions yet.

Repotting was a good idea, but applying hdrogen peroxide is not. It's quite agressive and can damage all the fine root hairs and possibly kill the growing tips. That may be what you are seeing (dead root which is molding), though you shouldn't be seeing moldy bark. My inclination would be to not mess with the plants any further than that. Water when they need it, and keep an eye on the mold issue.

mvmgems · #3 06-15-2021, 03:38 PM

Quote:

Originally Posted by camille1585

Welcome to Orchidboard! Sorry that no one has tried to help you with your questions yet.

Repotting was a good idea, but applying hdrogen peroxide is not. It's quite agressive and can damage all the fine root hairs and possibly kill the growing tips. That may be what you are seeing (dead root which is molding), though you shouldn't be seeing moldy bark. My inclination would be to not mess with the plants any further than that. Water when they need it, and keep an eye on the mold issue.

Bumping since I’m experiencing the exact same issue. Mini phal with rotting roots due to old nursery sphagnum, treated with peroxide (before finding this board), and repotted in repotme phal mix with slotted pot. It was continuing to decline so after a month I unpotted it to check the roots and found most of them had continued to die. I kept it bare root for a few days to dry out, with once a day soaking in KLN, then repotted in same pot / similar media two days ago.

Checked the roots today and visible roots had white mold mycelium growing on them. Not sure if I should continue to care for them as a typical phal and hope fresh roots come soon (as it does have four small leaves), or get some fungicide like physan.

OP, did your plant ever improve?

estación seca · #4 06-15-2021, 03:42 PM

What are your day/night temperatures? Humidity? How are you watering?

mvmgems · #5 06-15-2021, 03:50 PM

Estacion, you're like an orchid genie with how fast you respond!

My day/night temps are low 80s to mid 60s, with RH 30-45%. It has been living a few feet away from a south-west window that has relatively thick blinds drawn during the afternoon-early evening hours.

It's potted in a small (3") slotted pot and 0.5-1" bark-perlite-sphagnum mix, and I water by soaking ~10-30 min every 5-7 days when the pot feels light and dry all around (bottom, sides, top). It sits in a glazed ceramic cache pot that's a bit snug, so I put bamboo skewers between the plastic pot and the ceramic pot to have more of an air gap.

The roots aren't visible in the pot as so many of them have died and been trimmed away. It was last watered two days ago with 2.5 mL KLN per 2L water, and the pot still looks moist.

mvmgems · #6 06-19-2021, 09:31 PM

Update - I could see spreading round grey-green balls through the plastic so I unpotted to check. The same mold was also starting to colonize some of my bamboo skewers. It’s on both dry/papery and firm roots, but there aren’t a whole lot of roots left. The media looks fresh and totally fine. What should I do?

estación seca · #7 06-19-2021, 10:42 PM

Sorry not to respond sooner. For some reason the software didn't show me that you had replied.

The remaining roots look adequate; most are alive, and there are enough of them to take up water. The leaves are not wrinkled, indicating the roots are providing adequate water.

The mold is the type that grows on dead plant tissue, and will not invade living roots. I suspect most of the root problems are due to the hydrogen peroxide. I expect the plant to grow new roots.

I suggest you stop unpotting the plant. They are slow growers. I also suggest in the future not cutting off any roots. I can't often tell which ones are alive or dead, and struggling plants need all the roots they have.

Pot it in your mixture. Continue watering as you have been. Bamboo skewers in orchid media will almost always mold.

If you're willing to spend a few dollars wisely, get some KelpMax from First Ray's. It is a root growth stimulant. I and others here on OB use it regularly. Use the dilution on the label and water your plants with on arrival, then once a month.

Shadeflower · #8 06-19-2021, 11:01 PM

hi mvgems, I thought the orchid genie would have handled this already but I see you haven't solved this yet so lets see what you have done so far.
Your sister seems to have given you the best advice but you can't just boil it, yes that will have killed the fungus but the bark was degrading already and boiling it makes it degrade even faster after so boiling will solve the problem for 2 days after which the problem will flourish worse.
You say you can't get supplies easily. How about some clay pebbles from a hydroponics store? That is something I can always source easily. It's not my preferred substrate to use by itself, a very recent trend I have seen on the forum has been to add rockwool cubes, also available at the hydro store so I'd recommend you get that too and you'll have a cheap easy fix to what to pot it into. Clay pebbles and rockwool cubes have the added advantage that they cannot mold.

A further issue I noticed is that you used 3% hydrogen peroxide. Hydrogen peroxide is a great disinfectant but orchid roots can get burnt easily, even from excessive fertilizer and 3% HP burns roots slightly. It won't kill the roots but it will stunt them for 3 months and it will lower their defenses to mold, you have noticed that even live roots started going moldy. That is because of the Hydrogen peroxide. In low concentrations it will kill mold and rot but too strong like what is sold in pharmacies will also burnt roots.
Nothing you can do about it now but your best course of action is to throw out all the old substrate, start with fresh media. Wash all the roots under the tap and rub the mold away.

Then you need to lower the humidity. Bamboo stakes going moldy like that indicates that your home is possibly too humid, this will not only be an issue on bamboo sticks but on walls eventually too. If a home has too little ventilation and stays too humid then mold naturally starts growing on stuff. Pets, hanging up washing, people, plants all add moisture to a home and after it rains opening a window can actually add moisture so it is important to let trapped moisture escape when it builds up and do it when its dry out or mold starts growing everywhere even on clothes! Otherwise if you live in areas where it stays humid for extended periods a dehumidifier is a great addition to a home. Yes they cost as much as a fridge but they last as long as one too and you wouldn't have a home without a sink or a shower so having a dehumidifier in a humid climate is a vital asset to a home like having a smoke alarm fitted.

WaterWitchin · #9 06-20-2021, 08:56 AM

I see you're in Northern California... try incorporating some redwood bark into your mix. As ES says... don't keep unpotting. Put into some fresh media. Plant needs to recuperate. Can you take it out of the cache pot for awhile, and get some air movement going around it? Maybe even spend some time outside on a porch or balcony where it's in shade?

The dehumidifier isn't necessary. ShadeFlower likely missed the part about your RH being 30-45%.

You could always do a dip in a fungicide if it continues.

Phalaenoptics · #10 07-01-2021, 11:07 AM

I had a similar issue previously with mold issues

I wish I had read this thread earlier, before I corrected and overcorrected and ending up damaging the plant further.

I think a problem a lot of new growers have is wanting to see results right away, and then feeling helpless when the problem returns. Or, maybe feeling like your orchid's environment should also be pristine and spotless (I know I do!)

so, a few questions for the experts, for the benefit of learning:

1.) if you unpot, rinse off all the mold, and repot in new media -- and the mold returns (meaning the spores were on the old roots that continue to decay), what should you do next?
Do you continue to unpot and rinse off the mold, or should you leave it alone?

2.) Is having some mold in the pot okay? How much is too much?

3.) I know orchids are slow growers, however I lack experience in just how slow. If you're dealing with an issue and have applied the regular fixes: unpot, clean, repot in new media, apply Kelpmax - how long should you wait before seeing improvement? 1 month? (and what if the orchid continues to decline in this time? i.e. dropping leaves)