aussie dendrobium dropping leaves :(
 

my dendrobium hybrid is dropping leaves! i got it a couple years ago and it's bloomed twice now. it was a very robust plant, and i really don't want to lose it now, but I'm not sure why it's dropping its leaves. we had a few hot spells recently; not sure if that's the reason... the plant's potted in sphagnum, which I know isn't ideal for these plants, but I don't water very frequently, so I don't think it's root rot... your thoughts?

edit: a couple of the pseudobulbs look dark brown/black; they're actually just dark red due to sun exposure. the taller growth which lost its leaves is a new growth (grew this year). it lost its leaves before they even matured. the one with yellowing leaves is from last year, i think. both have yellowing pseudobulbs (or canes), and a couple other of the pseudobulbs are starting to turn yellow as well (they used to be green on the shaded side, red on the side exposed to the sun). not sure why this is happening...:dunno:

second edit: just remembered to say that the plant was placed in the garage for a couple weeks while the new growth was maturing and got transferred back into the house a couple weeks ago. the leaves started to grow after the orchid was placed back into the house (the cane was still growing in the garage). so i'm not sure if the time spent in the garage has damaged it. hopefully this is just environmental damage and not a disease...

Well, new growth is dying which is not a good sign.

If it was me I would inspect the roots very thouroughly.

Spagnum is naturally antifungal for first 2 years, then it degrades from what I know so if it has been in spagnum for past 2 years I would tip on rot in the rootzone which should be cut away with sterile scissors, then repot in some new media.

Maybe see what someone more experience has to say.

The pics you uploaded look like your orchid is in bark. Did you recently repot it into sphagnum or vice versa? How did the roots look? Also did this just start happening when you moved it out from the garage into its normal spot?

I have had leaves yellow and drop, or had new growth abort, like this when one wasn’t getting watered frequently enough and also when I had one with a poor root system.

It could also just be a response to stress from changing the conditions around. To me, it doesn’t look like disease and these bounce back pretty quick even if you do lose a few leaves or a growth.


I can say for sure that it is not from high temps. These seem to be pretty darn tolerant and most of my Aussie Dens can easily handle temps into the 90’s and our occasional low 100’s. One of my species slows down in the heat (Den tetragonum), but not my hybrids. I’m not sure exactly where you are in the Bay Area but much of that area has similar, often better, humidity than I do in the South which helps buffer the heat. Plus you have a MUCH better cool down at night than what I have. I really wish I still lived in Nob Hill or the Sunset district in SF so I could grow some Masdevallias and Draculas and high elevation Dens... sigh

sarajean,

thanks for sharing your experiences. hopefully it's just a watering issue.

to answer your question, the plant is in sphagnum with a layer on bark on top for aesthetic purposes, and to prevent algae from growing on the moss underneath (blocks the sunlight). the yellowing started a couple days ago, but i moved the plants out several weeks ago. the new growth was severely tilted towards the sun - the cane is curving just a little in the photo, but the leaves were tilted nearly 90 degrees to the window, so i turned the pot around, hoping to encourage the plant to straighten up. it did, and that's when its leaves started to turn yellow. could it be that the plant was trying to straighten up and its water-transporting vessels couldn't deal with the strain? or does the yellowing have nothing to do with that at all?

i'm a little paranoid that maybe it is a disease because I acquired a new miltoniopsis from the farmer's market recently and while it looked healthy, one of its neighbors had these very strange streaked petals almost like impressionist art, which reminded me of virus (although the flower form and plant form was fine). could the leaves dropping be a sign of a virus weakening the plant?

At my place in north-east Australia, the humidity isn't super high, but it's not too low as well. I grow my hard-cane dendrobiums in scoria rock in quite large diameter pots. Some of these are just placed outside among shrubs or trees - out in the open. Their roots are well established, and big bunches of aerial roots, some roots even grew through the bottom holes of the pot and into the soil underneath. I don't have to manually water them at all. Their water just either comes from the lawn sprinklers for watering the grass, or from the air. I don't manually fertilise them. They just get their own nutrients from the ground. And they've been growing like that for 20+ years - undisturbed. Flower buds are forming on the flower spikes at this particular time, right now. I might do an update to show what this all looks like.

The wild dendrobiums here - as expected - hang off trees and/or rocks. The ones appear to just survive and thrive without anybody doing manual watering at all. They can also generally handle direct sun quite well - except for super intense, which some leaves might burn, but doesn't kill the plant.

Adequate air-circulation helps to prevent issues. Maybe having the plant inside a garage for 2 weeks could be the link. This could be important.

Whenever abrupt yellowing or browning occurs, an if there's a lot of it ----- then maybe the first step is to unpot the plant and inspect roots to make sure they're ok. And, if possible, if there's enough pseudobulbs, break off 1 or 2 ----- and grow them separately. That's the nice idea of spreading the eggs out in different baskets. Just like digital data and files ...... having 'backups' is a good thing.

The attached photos only show that dendrobiums can take a real beating from water, and take a real beating from full sun, and just thrive (like in the wild) when they get enough water and air circulation and enough light. They don't even seem to get any viruses, fungal issues, bacteria etc once they've established themselves out in the open.

thank you for the replies! however, i have to report that it's getting worse. the yellowing has spread to another growth (yet another recent growth; it came from last year). would unpotting/possibly repotting the orchid put too much stress on the plant (should I just wait and see)? by the way, the "plant" is actually a mother plant with three keikis. the tallest growths are all from the keikis, which just shows how robust this plant is. you can see why i'm so confused as to why its health is suddenly failing...

I think it's worth repotting. Check the roots to see if they're ok. You could also probably plant the keiki offspring in other pots too. It looks like there's plenty of chance for this plant to recover right now.

One other thing ----- what is that whitish colour on the side of the pot due to? If it is the white colour of salts, then it could mean that the orchid has a problem with accumulated salts in the potting media. But I'm not sure yet.

---------- Post added at 12:23 PM ---------- Previous post was at 12:14 PM ----------

So ....... first thing might be to see if that white material is salt from fertiliser. If so ...... just repot straight away with new growing media. If that's all it is, then the plant should be ok after that.

I did suggest to inspect the roots.