Help identifying stem rot on struggling phalaenopsis - Orchid Board

AnnekeR · #1 08-30-2020, 01:30 AM

Hi everyone!

I’m new on here and sadly, despite my best intentions I have a pretty poor track record when it comes to orchid care. I currently have 3 orchids, 2 of which are not doing so well, but I am determined to revive them if at all possible and would greatly appreciate any advice!

This little Phal is a couple of years old, and I finally got around to repotting it for the first time. Most of the lower leaves were yellowed and shrivelled and fell off when I touched the plant. Where they came off there was a black-ish and very dry section left behind at the base so I peeled back several dead layers to reveal the stem underneath. It seems pretty narrow and dry, but looks like maybe some new roots emerging? It’s not squishy and as far as I can tell it doesn’t smell so I was unsure if the leaves falling were a result of rot or just neglect?

I’ve also noticed a single small black spot
in the centre of one of the remaining leaves. Could this be an infection or perhaps sunburn. It was in a very bright window.

Thanks in advance for sharing your expertise. Really hoping this one still has some life left in it!

estación seca · #2 08-30-2020, 02:55 AM

Welcome to the Orchid Board!

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

SouthPark · #3 08-30-2020, 07:14 AM

Welcome to the forum. Your phal that is a couple of years old is certainly hanging on - and the leaves look alright actually.

The roots above the sphagnum moss certainly does look a bit shrivelled, but maybe not severely shrivelled yet ..... from what can be seen so far.

The general recommendations for growing orchids is just to ensure that they're provided with suitable growing temperature and suitable temperature range ...... suitable light levels and suitable lighting duration for each day ...... suitable humidity ........... airy growing media (which includes good drainage pot) ............... gentle air-movement around leaves and roots and through media (natural air-movement or otherwise --- eg. from slow moving fan).

And importantly as well ----- water the orchid in ways that avoids drowning roots or even portions of roots. Orchid roots require enough oxygen to survive. So if water in or among roots gets too low in oxygen ------ then roots can die (or portions of roots) ------ leading to rotting and the orchid not being able to get water and nutrients into it.

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AnnekeR · #4 08-30-2020, 08:23 AM

Thanks for your reply. The temperature wouldn’t go below 10 degrees C overnight and up to around 22 during the daytime at the moment. I did have it in a very bright window right on the window ledge but read that phals don’t like to be in too much light so have just relocated to a different spot - still well lit, but not so much direct sunlight. As for humidity, the air is extremely dry as we have ducted heating running around the clock. I’ve potted it in some fairly lightly packed “orchid mix” (looks like mostly bark I think) with a layer of pebbles at the bottom of the pot and a thin cover of sphagnum moss around the top to try and keep a little moisture in. I’m lightly misting daily and not using any fertiliser at this point as I’ve only just transferred it to the new medium about a week or 2 ago. My main concern is whether I need to treat the stem and/or the black spot on the leaf with any hydrogen peroxide/cinnamon if it has developed rot?

SouthPark · #5 08-30-2020, 08:39 AM

If the black patch is dried up (hard and dry) and isn't spreading, then that will be absolutely no problem.

Abrupt changes in leaf temperature, such as going from cool to hot (or vice versa) in relatively short durations of time ------ can cause some cell collapse in leaves. So areas or patches can bust ...... or just be destroyed ...... not necessarily fatal, but also injuries etc can lead to undesirable situations.

So ----- conditions like, cool leaves, and then a burst of sunlight coming through for a long time with high intensity - can warm up the leaves quickly ...... and cause some issues with leaf cells. Sun-hardened orchids may be more resilient against that ..... but they can still get impacted ----- just depends on conditions.

No need to use hydrogen peroxide or cinnamon here in my opinion. Just monitor the condition.

Also, for some growing areas - misting leaves/stem etc can sometimes result in unwanted activity on leaves/stem etc ----- that's if the water stays on the leaves/stem etc for too long - especially if the air is still. Maybe ok in your home - due to the dry air. But keep that in mind anyway, just in case.

As for hydrogen peroxide ------ probably no need to ever use that on orchids ----- not on any part of them, especially roots. Maybe it's ok on leaves (not sure though) ------ I've never used hydrogen peroxide on orchid leaves before, which is not to say it doesn't have any applications on orchids. There are relatively inexpensive and longer lasting products for treating certain fungus/bacteria ---- such as with copper sprays for plants.

AnnekeR · #6 08-31-2020, 09:37 AM

Thanks so much! That’s great to know.

We have just moved house and it was left outside (undercover but still very cold) for a few nights before being repotted and placed indoors in a very sunny and bright window, so it had to endure a number of drastic changes in a short period after having not been touched for the entire rest of its life. Hopefully it will be happier once it adapts to the new environment and I’ll keep an eye on that leaf spot in the meantime. Hard to say if it’s getting bigger - if so it’s happening very slowly with no obvious changes over the past few days.

Thanks again for your knowledge and advice :-)

estación seca · #7 08-31-2020, 11:35 AM

10C / 50 F is too cold for hybrid Phals.

rbarata · #8 08-31-2020, 11:53 AM

Quote:

Originally Posted by estación seca

10C / 50 F is too cold for hybrid Phals.

Right!

AnnekeR · #9 09-06-2020, 04:13 AM

Can they tolerate those low temperatures if it’s just once or twice in a season? They wouldn’t be spending a sustained period in such cold conditions. It wouldn’t typically get that cold here - more like ~15C, but 10 deg is probably the lowest indoor minimum that we would reach on the odd occasion over winter.

SouthPark · #10 09-06-2020, 05:31 AM

Quote:

Originally Posted by AnnekeR

Can they tolerate those low temperatures if it’s just once or twice in a season? They wouldn’t be spending a sustained period in such cold conditions. It wouldn’t typically get that cold here - more like ~15C, but 10 deg is probably the lowest indoor minimum that we would reach on the odd occasion over winter.

Temporary is ok. We had temperatures of about 12C or so this season .... but that was temporary and was in the night time. Day time temperature was much higher.

Apparently the orchids have processes that require certain ranges of temperature etc to work well. Out of those ranges can mean poor system performance ..... even system failure.

Some orchids are resilient ..... but have their limits. Your orchid could probably do ok there. Will be great to hear of positive results in the future!