Yellowing Canes on Dendrobium - Page 3 - Orchid Board

Mercurius · #21 05-13-2016, 07:58 PM

That wet lesion I the first picture goes into the cane and bubbles a bit if the cane moves, so I'm guessing it'll have to come off..

silken · #22 05-13-2016, 08:47 PM

Your tag in the picture of the Dendrobium (Den. Fire Wings) indicates it is a Phal type Dendrobium as has been indicated. They are warm to hot growers. So it won't like getting a chill in winter or having wet cold roots. A smallish pot is usually recommended for Dens but leave a bit of room for growth.

You've been given good advice above on both the Den and the Oncidium. Good luck with them.

theloyalplum · #23 05-13-2016, 08:53 PM

D. Fire Wings is 3/4 Latouria so I would grow it like other latourias. Hot and bright light. Lots of water, but also lots of air flow around the roots. They also like to be shoved in small pots. They're pretty tough buggers, so I wouldn't worry too much about the rootless situation; just stake it up in its new pot and make sure it's watered well.

estación seca · #24 05-13-2016, 08:56 PM

There is a chance it can survive. The idea is to clean the plant of all rot; let it dry for a few hours; and put it into an environment of near-100% humidity. The plant may begin to grow new roots, at which time it can be potted up again. This may take some months.

Let the plant dry completely bare-root. Remove dead roots and anything mushy, into green tissue. Treat the cut surface with an antifungal, powdered sulfur or cinnamon. Let it dry for a few hours to a day.

Then use what is called the sphag-and-bag method. You can read about it if you search Orchid Board on this term.

Put the plant into an enclosed container with something to keep the humidity high. Some people use a plastic bag with some damp (not wet) sphagnum moss, and set the plant on top of the moss.

Others use a small terrarium with a tightly-fitting lid, or a very large jar or vase with a cover or a piece of plastic wrap. Put a cup of water or damp sphagnum inside to keep humidity high.

Then wait for roots. The plant may begin a new vegetative growth before it makes roots. Wait for roots.

When they are 2" / 5cm long, repot the plant into a very small pot. You will probably have to do something to stabilize the plant and keep it from falling over. Water it well, then let dry between waterings.

Mercurius · #25 05-13-2016, 09:04 PM

This one isn't Fire Wings, it's just an unidentified den. Fire Wings is still just a seedling. I do have a terrarium that's at 100% humidity. Would the misting be a problem, though?

estación seca · #26 05-13-2016, 09:14 PM

Orchids cannot take up water except through roots. Misting is harmful for orchids without roots. Misting rootless plants only wets the leaves and predisposes to fungal infection.

Misting rarely helps orchids with roots. I don't ever mist my plants. I sometimes use a spray bottle to wet just the medium of plants in small pots.

Some people use a misting system to wet the roots of large numbers of mounted plants at one time; this inevitably wets the leaves, as well, but healthy plants aren't bothered by this. But, misting with the intent of getting the leaves wet is not a good idea.

The purpose of the high humidity is twofold: To minimize water loss through the leaves before the plant makes more roots; and, to entice the plant to make new roots. The idea is to keep the plant dry in a very humid environment. A rootless orchid cannot take up water. You are trying to help it survive long enough to make more roots.

Mercurius · #27 05-13-2016, 09:46 PM

My terrarium has a misting system that mists for 10 sec/2x a day to water and maintain humidity, that's why I asked.

I read that KelpMax is supposed to help rootless orchids develop new roots. Should I give it a dip in a kelp solution before bagging it?

estación seca · #28 05-13-2016, 09:49 PM

I would not try to reroot orchids under a misting system. That is fine for healthy plants.

Kelp solution is good for helping orchids root. I would dip the plant, let it dry, then bag it. I have heard of people using it every 3-7 days when trying to reroot plants.

Mercurius · #29 05-13-2016, 09:59 PM

That sounds like a plan, then. Once it dries, I'll trim off the dead roots and infected canes, then give it a good soak in some warm kelp solution. After it dries again, I'll bag it up and hope for the best.

Would a bit of Physan20 in the water help, do you think?

estación seca · #30 05-13-2016, 10:11 PM

I don't use disinfectants on anything, including my own cuts and scrapes. Simple cleaning to remove dirt is adequate. I don't treat plants, nor myself, with any kind of antifungal nor antibiotic unless I definitely know there is an infection, and I definitely know, or strongly suspect, exactly which germ is causing it.

There are always germs on the surfaces of everything. We don't understand why some plants and animals become infected and others don't. We definitely know different germs on skin interact with each other, and there are non-pathogenic germs that prevent bad germs from causing damage.

Disinfectants kill some, but not all, germs on surfaces of things. They don't discriminate between good germs and bad germs. They don't penetrate into tissues. If your plant has a tissue infection, disinfectants won't help at all. If your plant doesn't have a tissue infection, the disinfectant might kill the good germs preventing your plant from becoming infected.