Dendrobium phal leaves yellowing after repot - Orchid Board

AsuSayo · #1 07-30-2020, 06:20 AM

Hi all,

I bought my first dendrobium a month ago.
I repoted into a bark mix a week later, because it was in a pretty bad mix.
A few days ago, it started to lose its flowers, which I expected would happen.
Two lower leaves started to yellow too, and today I noticed a different leaf yellowing in a strange pattern. (On the second picture, the spots are more yellow than on the picture)
It isn't the lowest and I'm concerned, that I might drowning my new orchid.
I soaked for 15 minutes once every 5 days, and just switched to 7 days, because the lower part of the mix was not dry enough. Should I water even less?
A new cane is already started to grow, so I don't known if it is a happy in bark or not?

estación seca · #2 07-30-2020, 07:12 PM

Welcome to the Orchid Board!

Your plant is still in good shape. It is probably a hybrid involving Dendrobium phalaenopsis and related species, or the Antennatum group of Dendrobiums. Or maybe a hybrid between these two types. They shouldn't dry completely during growing season. They also need to have plenty of air at the roots. When these are making new growth and they are in large bark, it is OK to water every day. So long as the roots have air around them you can water a lot. In general, orchids with thinner leaves tolerate drying out less well than orchids with thick, succulent leaves, and all orchids need to stay moist when making new growths, and have air at the roots.

People get into trouble when the medium has small particles and they water a lot. The air is excluded from the medium by water, and the roots suffocate and rot. Gently move some of the medium in your pot. If you can see good air spaces around your plant's roots, you can water more often.

The yellowing leaf is on one of the oldest growths. This is common. The older growths can drop leaves but remain green, supporting the plant.

The plant was probably grown in a greenhouse in near-ideal conditions of temperature and humidity. In your home conditions are not like in the greenhouse. It is common for some kinds of orchids to drop older leaves when moving into home care.

The larger leaf with the reticulated yellow pattern could be a number of things. It could be lack of water. It could also be spider mite attack. Hold a tissue under the leaf against the stem. Press against the undersurface of the leaf and pull the tissue to the leaf tip. If you see brown or reddish streaks on the tissue you have spider mites.

Also let us know the day/night temperatures in your house, how much light you are giving it, and the humidity.

AsuSayo · #3 07-31-2020, 07:29 AM

Thanks for the reply.

My plant sits in a huge eastern window, so it gets plenty of sun in the morning. The window has blinds and in front of the window a there is a grape arbor, so it is somewhat shaded too.
The humidity is around 45%, on rainy day it can be 55-60%. The front door is usually opened near to it, so it should get plenty of air movement too.
In past weeks, 28-30 C° is the usual temperature in that room. There were some rainy day, where it was 20 C°.

I checked the leaf, and didn't find spidermites with your method, so hopefully it just some watering or sun problem.
I made some new pictures of the leaf, it is more yellow today, and the underside is bumpy like yesterday.
All leaves on this cane and the older one has some discoloration, but they are frim and not sloppy.
The other 4 cane doesn't have this problem at least now. I'm worried, because it happened on so many leaves.

I didn't mention that it is actually two plants. When I repotted it, it separated into two parts, 3-3 cane.
The (probably)older plant had more massive root system, than the younger one. The younger plant started to grow new roots, that is on the fifth picture in my previous post. The older plant grows the new cane, and has the yellowing/patterned leaf problems.

It was potted into mix of very fine media (it seemed like it was soil) and some medium bark chips. But the biggest surprise was, when I pulled it out, it was actually attached to a big bark block. This was the first time I found something like this during a repot, it was quite shocking. I managed to chip away the block, and tried to be gentle, but I think I damaged the roots and the roots that were attached or grew into the block are probably dead now. I didn't know which roots were dead or alive, so i didn't trim the roots either during the repot.

The potting mix I used had large and medium bark chips, with bit of charcoal.
I used a bigger pot than the original. It only has drainage holes in the bottom, would it be better, if i make some holes on the side?

Other question, could misting the surface of the bark daily cause rotting of canes? I don't see anything like that, but the discoloration happened so suddenly, I'm bit worried.

I have 3 phalaenopsis, the dendrobium is so different compared to them.

Dollythehun · #4 07-31-2020, 08:02 AM

If that's one of the older canes, you're probably going to lose those leaves at some point. A healthy plant will have some leafless canes which are still feeding the plant. That's normal. Otherwise follow the advise ES gave.

SouthPark · #5 07-31-2020, 09:38 AM

Quote:

Originally Posted by AsuSayo

Other question, could misting the surface of the bark daily cause rotting of canes? I don't see anything like that, but the discoloration happened so suddenly, I'm bit worried.

If the dendrobium is given suitable lighting levels, and your temperatures sounds ok ----- and if you have some gentle air movement in the growing area, and if the air is able to move through the pot and media, and also move over the leaves and stem too, then that should benefit the health of the orchid. It possibly can help suppress some sorts of unwanted fungal/bacterial activity.

Misting the surface of the bark daily should be ok ------ just maintain some air-movement over the media, and through the media ----- eg. good drainage pot (with a good number of big enough holes at the bottom of the pot); and don't let the bottom of the pot sit in water. Ths means -don't allow the bottom holes sit in water of any kind.

Air should be allowed to flow through the media and through those pot holes.

Maybe you could use a pot stand or drainage great to raise the bottom of the pot away from the pot tray.

Click Here

estación seca · #6 07-31-2020, 11:51 AM

Now that I see the new photos I think it's lack of water. This can be from not being watered enough, or poor roots. Most orchids only make roots when new growths are forming, or will form soon. I try not to repot until the plant is making new roots.

When we repot we can damage roots. I don't think it's good to try and remove all the old medium. It damages roots badly. Only remove what comes off easily.

SouthPark · #7 07-31-2020, 04:11 PM

Great points and comments by ES.

Also - AsuSayo ---- if you suspect drowning of the orchid, then one way to check is to take a look at the roots within the medium, which could possibly require unpotting - to do the visual inspection.

And - from your pic (attached) - take a look at the circled regions. Not sure if the circled bit of the new growth is due to shadows - or otherwise.

AsuSayo · #8 08-03-2020, 01:08 PM

Thanks for replies.

The patterned leaf is yellowed and dropped during the weekend. The last leaf of the oldest cane and broken leaf are yellowing. The top ones are starting to get bumpy on that cane. Other cane of the older plant is still not affected, and the new cane is growing fast.

Thanks for suggestion Southpark, usually after watering I check the plant a bit later, and pour the water out form the pot plate. But something under it might be better.
And those dark regions only shadows luckily, it is just darker green under light.

I don't wanna disturb it more with unpotting, so I only removed some barks on the more problematic side of the pot. This side faces away of the window, always in the shadow. I made some pictures of it. This side is always wet, while most of the other barks are dry. This is why I'm afraid to water more, but the other side migth need the water. I think it needs ventilation holes on the side and might be better pouring water through it, and not always soaking it.

(Don't worry about the white spots on bark on the pictures, that just dirt, it got in during the repot, because I was too messy. I thought it would just soak out but it's still there....)

Next time I will be more careful with the roots during repot. I just tought in the long run removing the bark block would have been better.

At least I see 2 new roots from the older plant and the lower roots seems to be fine, so hopefully only these 2 canes will lose their leaves. Or the younger plant will take over, it sprouting crazy amount of new roots.

AsuSayo · #9 08-07-2020, 08:06 AM

So a bit of an update.
Yesterday another leaf started to yellow, on the 3. cane.

So I my worrying started again, and I went against my own words and unpotted the orchid.
The roots were pretty much all dead.... No wonder it started to drop leaves. The younger plant was in better shape, but the older one roots were the worst.
This time I decided to cut away the dead ones, there were a few that still had substance, but it was quite devastating.
These roots were probably half dead during my first repot too (they were in very soggy material originally) but with overwatering I think I killed a the few good ones too....
The promising thing is that the younger plant is already sprouting new roots, there are at least 8 new roots already. The older plant is making the new cane, and from the new cane 3-4 new roots already started to grow.

In the end I made two makeshift pot from water bottles, and seperated the two plants. The pots are much smaller this way, so hopefully this will end the overwatering problem.

I hope both of them will make through this and will get better in a few months.

SouthPark · #10 08-07-2020, 09:07 AM

Asu ----- thanks for writing an update about the condition.

I thought that was excellent in the way you decided to unpot to check on the condition.

If the root degradation appears to have been due to oxygen starvation, then try the method of watering the media toward the sides of the pot - similar to the way the diagram showed. You don't have to do it permanently ----- but could definitely try it out to see if it works nicely for you too.

You may have seen the following links as well - but if not, then I sometimes paste these links that could possibly be useful later - relating to water and roots.

Click Here and Click Here and Click Here and Click Here and Click Here

Once again - nice work with checking on the roots. When you do see yellowing - and if there is any feeling that it could be related to watery conditions in the pot - then unpotting is a great move.