Help diagnose and treat a few orchids.

[treefisher]

Hi,

I have a few orchids with problems. I'm hoping I can get a bit of guidance here.

The first picture is a Dendrobium that I've had for a about a year. It looked fine until a couple months ago. I noticed spots and yellowing on the new growth. I gave it a physan bath and clipped a few bad leaves. It seemed OK for a while, but now it looks like this. What is it? A disease or fungus?

The second pic shows some nice new roots forming. It wants to live.

The third picture is an Oncidium that I picked up at Lowe's a few months ago. It was mislabeled and on clearance, so I figured I'd try to salvage it. I'm having no luck so far. The psuedobulb on the left was shriveled when I bought it. The middle psuedobulb looked good, but now it seems to be shriveling up as well. The growth on the right has done nothing. It still looks the same as it did at Lowe's.


Any advice?

[King_of_orchid_growing:)]

I'll address the easier problem first.

Have you had good results from growing Oncidium intergenerics such as Miltassia and Brassidium, etc. in full moss in a net pot?

If not, I'd like to suggest using a clear plastic pot with wood chips and charcoal instead.

How are the roots doing on the Oncidium intergeneric? Do you have pics of these?

Second, your Dendrobium...

This is complicated, I'm not sure how to approach this one. So here we go.

It could be that it's being grown too bright that the leaves are yellowing. It could also be over fertilization. But I'm thinking it's more along the lines of old leaves dropping from an old cane (correct me if I'm way off base here).

I doubt it's bacterial or viral. If it would be a disease, it'd most likely be fungal. However, in my opinion, I doubt it.

Then there's the awesomeness of your Dendrobium growing new roots. That's good.

If this jogs any kind of inspiration and reveals any possible issues that need to be resolved, please do mention them.

In the meantime, let's see what others come up with.

[treefisher]

Thanks for the quick reply!

I had an Oncidium (Sharry Baby) a long time ago that was grown in Schultz orchid mix, in a clay orchid pot. It was a trouble free plant that lived for years until I moved from home. I left it in the care of my family and it ended up dead within a year.

This one came out of a Lowe's bag and was in 100% sphagnum moss. I tried to pull out as much moss as I could, and plant it in Schultz mix. I figured mimicking my old success with the plant would be a good idea. What you see in the picture is just a top layer of sphagnum to retain some moisture.

The roots looked better than I expected during transplant. I didn't see any real problem areas, and only clipped a few small roots. They were mostly thin however. I'm not sure how normal this is for this plant. Perhaps because they dried out too much? I'll remove the sphagnum to inspect the roots, and see if I can get a picture.

The problem leaves on the Dendrobium are all new. The old leaves look fine except for a few hard water spots.

This is a new cane that I expected would flower. Instead, I got what you see in the picture. I'm tempted to cut the entire stalk off. Would this be a good idea?

I don't think I've done anything different since the cane first sprouted. It lives in the shade on the east side of my house. I fertilize with (old) Schultz orchid food as per directions. It gets rained on sometimes, but not much because of its location. Water never sits on it for too long, and I haven't noticed signs of rot; unless that's what the picture is showing.

Thanks for the assistance so far. I hope I can save these things.

[Junebug]

Have you looked for insects on the underside of the Dendrobium leaves or have your day or night time temperatures recently dropped? What temperature zone do you live in?

I would not cut the cane because it stores energy for the plant. They shouldn't be removed until their completely shriveled and yellow.

I generally use 1/2 the recommended dose for any brand name fertilizer. Dendrobiums require some sunlight to initiate blooms. Your healthy leaves look a little dark which usually indicates not enough light. Bright indirect light or a few hours of early morning eastern exposure makes my Dends. happy. Be careful to gradually increase the light or you'll risk sunburn.

[King_of_orchid_growing:)]

Well that's not right if the leaves are yellowing on a new cane.

Could it be over potting? Aside from the new roots coming out of the new shoot on your Dendrobium, how're the rest of the roots on the older canes? Do the total amount of root mass really fit into that pot, or is there a lot of empty space?

[treefisher]

Sorry I couldn't respond sooner. I've been at work, pretty much since my last response. I hate how responsibilities get in the way of my hobbies.

Anyway...

Originally Posted by Junebug

Have you looked for insects on the underside of the Dendrobium leaves or have your day or night time temperatures recently dropped? What temperature zone do you live in?

I would not cut the cane because it stores energy for the plant. They shouldn't be removed until their completely shriveled and yellow.

I generally use 1/2 the recommended dose for any brand name fertilizer. Dendrobiums require some sunlight to initiate blooms. Your healthy leaves look a little dark which usually indicates not enough light. Bright indirect light or a few hours of early morning eastern exposure makes my Dends. happy. Be careful to gradually increase the light or you'll risk sunburn.

I have not noticed any insects on them. I will try and get a closer look tomorrow. I live in Southeastern NC. Zone 8 I think it is. Temps haven't changed much lately.

Maybe I'm using too much fertilizer, but that doesn't seem to be bothering another Dendrobium I have.

I thought the older leaves seemed a bit dark too, but I figured it was probably just because they were older. They've always been darker. This plant also gets the light you recommended; "a few hours of early morning eastern exposure."

Originally Posted by King_of_orchid_growing:)

Well that's not right if the leaves are yellowing on a new cane.

Could it be over potting? Aside from the new roots coming out of the new shoot on your Dendrobium, how're the rest of the roots on the older canes? Do the total amount of root mass really fit into that pot, or is there a lot of empty space?

It's neither too tight nor too loose. It's snug, with some room to grow. I'm not sure how the older roots look now, but they looked OK last time I repotted. I guess I could sift through the medium some, but I don't want to put the plant through any more stress than it already appears to be going through.

I'll have some time to tinker with my plants tomorrow. I'll try to give an update and more details if I can find any.

[Junebug]

I've been pondering over the condition of your Dendrobium. I grow quite a few of them and one time I had a problem similar to yours. The condition only affected my newest, longest cane. It took a while to become obvious but eventually I discovered the cane had suffered an incomplete crack near it's base. It still had enough undamaged structure to remain upright long after the injury but the leaves were the first to go. I decided to leave the injured cane alone and let nature take it's course. Eventually the cane succumbed and fell over. It was still attached by some fibrous tissue but at that point I completely removed it because there was no hope left for the survival of the cane. The plant did not seem to suffer and promptly initiated new growth.

This may not be the problem with your plant but you might want to carefully inspect the full length of the failing growth. Closely inspect the base where the growth emerged and while doing so try giving the cane a GENTLE jiggle to see what happens. This is how I discovered my underlying problem.

[treefisher]

All the leaves on that stalk turned almost completely yellow and fell off overnight.

I was hoping you had something with the broken cane theory. I inspected it well and couldn't find any problems. I also sifted through the substrate and all the roots appear to be in good shape. There are also quite a few new roots I didn't notice before.

I think I might repot and relocate it. I would normally wait for the postflower, but it doesn't look like I'll be seeing any this time.

[King_of_orchid_growing:)]

How low does the temperature drop at night? Especially during the winters.

And do you mist the leaves of your Dendrobium?

[treefisher]

The temps were averaging about 70-75F overnight. Last night it got down to 65, which is the lowest it's been in months.

I'm summering 3 other orchids outside next to this dendrobium. All but this one are in good shape. I don't mist it. Should I? It does get rained on occasionally. I try not to let water sit on them for long when that happens.

When I first got the oncidium, I read somewhere that I should mist it in lieu of regular watering after transplant. This was supposed to help it acclimate to new surroundings easier; assuming it lived in a very humid environment for a long time ( a Lowe's bag). I questioned that but tried anyway. It just shriveled more, so I began regular watering. I seem to be getting the same results either way. You think the "sphag-n-bag" method would help here?