How to save a Dendrobium 'Samurai' (Sameri) - partly dying and new growth
 

I have a pretty large Dendrobium Sameri (Samurai). It has been gradually, steadily losing leaves since soon after purchase.

Before the last of its previous leaves died off, it put out a new growth. This growth has sprouted steadily and seems healthy, though there are some dark marks. I have used a 3 in 1 treatment.

I hope the pictures helps clarify. As you can see most of the plant is barren, except for a single green growing stem.

Also, there is a spot which I am not sure is keiki or air roots (if keikis can form naturally, that is) Should anything be done with air roots? And if it's a keiki, how do I cut to propagate?

The growing medium has collapsed somewhat. Should I entirely repot the plant, including roots associated with the new, healthy growth? (That is, if certain roots can even be associated with certain growths) I am wondering, because might repotting interfere with the conditions allowing the healthy growth? I am leaning towards full repotting... as perhaps even the new growth will soon lose its root support.

:thanx:

Photos are of such small size, I can't see that much...but given that...
Err since that's an antelope dendrobium, that looks very sad, potentially fatally so.
It should be full and leafy and since it's not, it's probably a root issue. Have you inspected it?

Thank you. Sorry about the tiny pics, though I think you can zoom or open them.

I haven't checked the roots. Should I cut away dead roots and stems, and repot?

On a Windows computer (no idea on a Mac), click on the picture to open then on your keyboard hold down the Ctrl and Shift keys at the same time with 1 hand and tap on the + key at the top of your keyboard to zoom.
At some point the pic will get too fuzzy to see better.

To zoom back out hold the Ctrl and Shift and tap the - key just to the left. You will see a little box at top right with the percentage and let it get back to 100%.

Dead roots (unless masses of them) aren't a problem in themselves. Whatever conditions (like drainage) might be causing dead roots are of concern.

You may have read that most people prefer to repot an orchid immediately upon taking possession to get it to a known state of drainage. I often do that (not always). If you don't know the state of the orchid root system and the potting media, well it's probably the best way to figure out what's going on.

Most (if not all of us) have killed many orchids in our journey getting where we are. I think that most orchids that I acquire (if I don't get something totally out of my climate like Dendrobium cuthbersonii) are likely to live and grow now. That's after making sacrifices to the orchid gods on and off over 35 years or so. I still make the occasional sacrifice for reason unknown. Part of that is learning the growth habits and tells of a group or a species.

How have you been watering it? What are temperatures day/night? Humidity? Light? When was it last repotted? How long have you had it?

I get, and appreciate your statement, though it'd be a shame to lose this one! Well since the medium has collapsed, and for the reasons you've stated, should I not go ahead and repot, checking the roots? (and cutting dead roots and canes?)

Well it was purchased early April. this year. I have not repotted yet. They are kept outside now. I use humidity trays, and monitor the humidity on the weather app. And btw on that note I would like any opinions about the value or necessity of an outdoor mister/fogger, when the air gets dry! You guys have told me that somewhat low humidity during the day can be compensated with nighttime humidity, along with other methods to maintain humidity.

Yes, but...often people over-zealously remove living roots.
Good luck with it.

Update on Dendrobium Sameri
 

Thank you once more. I repotted, and found that a section of canes and roots was completely dead. They came right apart, leaving the great majority of the root system healthy, with what you see above substrate in the pic! So hopefully saving so much roots will speed regrowth, I presume?

So the canes/stalks (not sure of the correct term for Antelopes) without leaf growth are still solid, green and healthy. Should I cut them anyway? Or will they sprout leaves again?

Or should I maybe use keiki paste on them? My understanding is keiki paste is most likely to make flowers, a baby plant in rare cases. Will it possibly cause leaves to sprout?

Let me up front state this is an opinion. Too many people 'do things'. The plants know how to grow, stop trying to mess with them and just provide good conditions and let them do it. More plants die of 'over attention' than neglect.
Don't remove living healthy tissue, the plant will let it go when it's ready. Don't overthink it. Just provide good conditions (food, water, light, shelter) and let it do it.
No, the canes will not releaf, but they *may* flower if the conditions improve. Conditions should warrant healthy growth and leaf retention. You should have at least three or four growth cycle of leaves (general rule) providing photosynthesis. You have almost none. Either the plant was in poor condition when you bought it or it's deteriorated under your care.