Some (if not most) potting soil contains some type of manure. Soak that in water and Anaerobic bacteria proliferates and this is what causes most things to rot and die.

If you're trying to propagate with cuttings, do it with sphagnum moss. Cut the canes so that you have at least a couple of nodes in each one.

Place the sphagnum moss in a bucket of water until it's thoroughly soaked. Get a clear sealed container, or use a Zip Lock bag (works well).

Squeeze most of the water out of the moss, and place a layer of moss in the container. Since your cuttings have mold, spray the ends with alcohol to kill the mold.

Some people will even dip the cutting in rootone or some kind of rooting medium.

Place the cuttings in the moss slightly covering the top. Seal the container and place in a shaded area. Cross your fingers and hope for the best and if it's going to happen, it will take about a month.

Go to YouTube and check this out: How to propagate-Dendrobium Nobiles where a woman did exactly this. About 7:30 minutes into the video. Good Luck.

Should I spray with pure 70% alcohol or a 50/50 dilution?

Since the ends are open, I might try the 50/50 dilution. Good Luck!

Ok, so I was planning to move the cuttings to sphagnum, but then something happened and I had to leave. I kind of forgot about them after. I remembered them today and checked-

I think there's a new growth emerging from one of the canes! :D

(bottom cane in first and second pic, right cane in third pic)

Is there any chance it could be a flower spike and not a keiki? I hope it's a keiki and not a spike.

Its currently sitting in a room that is around 82*F during the day and 75*F at night.

I'm planning to move them into the sphagnum moss tonight, or at the latest tomorrow. Will Miracle Gro sphagnum peat moss work or is that a no-no? It doesn't look like the moss usually used for orchids.

Don't cover the container. The canes look rotted to me but if you see something alive, go for it.

When I try to get keikis from a cane, I just lay them on a table or plate with no media at all. Not necessary. Sometimes it can take many months. I wouldn't put them in moss or anything else unless you see roots. Just let them dry out.

The keiki (new growth) will take water and nutrients from the cane. Not from the potting mix.

Jane

Here's a closeup:

Nothing new on the top one.

I'll take them out and lay them on a paper towel. Does that sound good?

Yes, that is a new growth. You can take it out of the media and let it dry. You could leave it where it is just don't water the media until you see roots. Once you see root formation, plant in some small bark with a little sphag. Do not cut it from the cane. You could cut the bottom of the cane off as it looks rotted. Just lay the cane with the new growth on top of the media. If roots are forming, they will grow down into the bark.

Good luck, looking good!

Jane

Update:

I see a small root tip emerging from the bottom of the keiki. Should I move it to sphagnum?

I bought a bag of MG Sphagnum Peat moss, but when I opened it the mix didn't look like the moss used for orchids. I assume it's not the right sphag? If so, where can I find sphag? I didn't see any for sale in he local Home Depot.

This is the stuff they sell at my local Home Depot http://www.homedepot.com/p/432-cu-in-Sphagnum-Moss-110/202745057

You don't want anything with Peat in it. I would leave the cutting until you have actual 1 inch roots and preferably more than 1 root. Good luck!

When you have at least 3 roots 1 inch or longer then do this...http://forums.gardenweb.com/discussions/4006610/dendrobium-keiki?n=5 good luck

I noticed a small white bug crawling around on the keiki today. It was very small, maybe about 1/5 mm. Looks sort of mite-like. It moves extremely fast, like an ant on a sidewalk. Any idea what it is, and should I be worried? The keiki looks fine.

Spray it with alcohol. Dab them with a alcohol que tip. for an occasional bug.

Update:

I ended up moving the keiki to sphagnum moss sometime around the start of August. The other cane has gone dry, but however:

The keiki is moving along swimmingly!

There are about eight roots, all with healthy growing tips. There is also what seems like a new leaf emerging. Yay!

I keep it on a windowsill with southwestern exposure. I water it by placing the container in a bowl of water, letting the sphag wick up the water to the surface.

Do you think winter could set it back at all? I'm assuming with less sunlight in the winter months that its growth will slow down.

By the way, this was the original orchid that the canes were removed from:

The cane with the keiki now is the cane that has two dying leaves clinging to it in the picture. Any ideas on what type of dendrobium this orchid is?

It is a Hard-cane Dendrobium. It needs warmth,bright light and humidity and a very slight cool down in Autumn to induce flowering. Easy in Hawaii, Florida and places with a similar climate.