Dendrobium Leaves Turning Yellow & Falling Off

[scy]

Hi Everyone,

I'm new to caring for plants and received 2 orchids as a gift about a month ago. I have a Cymbidium Insigne and a Dendrobium Hollywood. I do not have a problem with the cymbidium at the moment, just the dendrobium. Sorry in advance for the long post. I figure more details is better than not enough to save my orchid.

Problems:
1. The dendrobium's leaves are turning wrinkly, yellow and falling off a day or so later. As far as the leaf turning yellow, it's the whole leaf and not part of the leaf. (All other photos other than 1st & 2nd)
2. Has scale
3. Strange brown bump on rhizome. (Pic 2)

Growing Conditions:
I have my orchids behind a sheer curtain of an east facing window. The daytime temperature reaches anywhere from 72-75 degrees and night temperature of 60. For humidity, I set the pot on top of a tray full of pebbles with water (but I made sure the water level never touches the pot). I use a wooden stick to help me figure out how dry the medium is rather than sticking my finger in. (Pic 1 shows original pot & what it looked like originally.)

Actions Taken:
1. The original pot had poor drainage and was densely packed in sphagnum moss. I did not water it for nearly 2 weeks, because the moss was still very damp and wet. After I realized that the moss was too densely packed and it wasn't drying, I repotted it in a clear, plastic pot with plenty of side slits and drainage holes.
2. I also changed the medium to a medium bark mix. I soaked the mix in water overnight before potting it the next day. I also sterilized the pot and cutting shears with physan before beginning the repotting process.
3. I checked the roots and saw that they were thin. Some tips were black and gray, so I cut those parts out. After I was done trimming the roots, I soaked it in Physan for a few minutes to kill off any bacteria and repotted in the new pot. I repotted again a few days later, because the stem was very wobbly. I packed the bark more tightly.

A week later, the bottom leaf started to turn wrinkly and yellow. I've read that this could be due to lack of water, lack of nitrogen, or too much sunlight. I bought some fertilizer 20-14-13. The instructions said to use 1 tablespoon/gallon every 2-3 weeks. I read that "weakly weekly" was the best way to go, so I have been using 1/8 teaspoon per 1 liter of water.

When looking at the yellow leaf more closely, I noticed that there were small white spots that turned out to be scale. I used a cotton ball with rubbing alcohol to swab the leaves, stem and flowers and it left behind pinkish spots on the cotton. I immediately separated the two plants. I have been swabbing the plant once a week after watering.

A few days later, the bottom layer of green leaves turned yellow and the original yellow leaf fell off. Now the middle section of green leaves have turned yellow. I only have the 2 top leaves left that are green. The flowers are still beautiful and have not dropped.

I watered it again on Sunday and swabbed for scale. There was very minimal scale on the leaves and stem. I did find more of it closer to the flowers. Today, I saw an odd brown bump on the rhizome that was not there before.

Thank you for your help and advice!

[Donald]

Some dens will loose their leaves in the winter, at least one of the many I have do, and is doing presently. If that's all it is I wouldn't be to concerned. Is this your first year with the den? I usually pick off any scale when I encounter them. Seems like everything your doing is OK. No doubt you will get more advice on your predicament.

[ardera]

I don't know about Dens, as I haven't been brave enough to try them yet (don't know if I can provide sufficient light). But would it even get enough light in an east window, behind a sheer curtain? Even my phals direct sun in my east window. I don't believe that a sheer is necessary, and you are probably not providing enough light

[Connie Star]

Welcome to OB, by the way!

[scy]

Thanks for responding so quickly! Can anyone tell me what the raised brown spots are in picture 2? I want to make sure it's not some sort of pest or disease.

Donald: This is my 1st month with plants ever! I didn't know that dendrobiums shed their leaves. Thanks for shedding some light on this. I didn't know that their dormant stage meant shedding leaves. I just thought it meant that the flowers would fall off and I'd be left with the stalks and leaves.

Ardera: I hope that's not the case, because that's the brightest window I have. Most of the photos I took were at night, so that does not reflect how much light it's receiving. Since I found scale, I moved it away from the cymbidium, so it does not have the sheer curtain.

Connie Star: Thank you so much for the warm welcome!

[King_of_orchid_growing:)]

Your particular Dendrobium shouldn't be losing all the leaves like yours has been doing. It should only shed the lower leaves until the cane is completely bare over a period of maybe a couple years or more.

I think the leaf loss is related to the poor health of the roots.

The pot you have the Dendrobium in may still be too large.

Have you considered possibly trying another Dendrobium should this plant decline further over the course of the next few months?

I'm sorry to be the bearer of bad news, but my opinion of this plant is that it may most likely be doomed.

[King_of_orchid_growing:)]

The brownish spots on the cane in pic 2 is not scale.

I'm not quite certain if it's mechanical damage or sunburn. Worse case scenario it's rot (it may most likely not be).

[King_of_orchid_growing:)]

See if removing the spike will help relieve the plant a bit.

Remember to sterilize your cutters! Cold or heat sterilization of your tools is irrelevant, just as long as they're sterilized.

I still think that this plant would have a difficult time rallying back, according to my experiences with Dens, but it's worth a try.

[BobInBonita]

Your orchid looks VERY sick. I agree with the King that its likelihood of survival are low, but wanted to ask a few questions that MIGHT help you understand what happened so your next orchid fares better. It might also point more towards possible survival. The questions come from just a few of the errors I have made, so don't feel bad if you did something - learn from your mistakes. I'm still learning (too frequently sometimes). If you didn't do anything wrong, the plant was probably terminal when you got it - but even that is a learning lesson - check the roots, not just the flowers, before you buy.

It looks like a time sequence, with the first pic a healthier plant, then progressively worse. How long apart were these pictures taken? Was it a sudden decline or over a few months?

THe 4th pic show the lower leaves yellowing but the top leaves still green.

Since some of the lower leaves are on new outgrowths - was the plant exposed to bright sunlight, with the top more shaded than the bottom?

How long and what concentration Physan did you use? - the same pattern of new shoots dieing faster than old canes can happen with chemical poisoning.

Did it go downhill suddenly after the first or second repotting, or was it already fading fast?

You mention the root tips were black - were they firm or mushy? About what percentage did you trim? The roots are the intestines of the plant, where fluids and nutrients are absorbed - People don't do well with chunks of intestine removed but sometimes its necessary for survival orchids are the same Messing with their roots is mmajor surgery and should be performed as seldom as possible.

Dendrobium roots are frequently very thin or fine compared to many other orchids, so that wasn't an issue but the color might have been rot. The fact that there were new outgrowths makes me less suspicious of root rot.

Many dends are grown on tree fern. Did your dend have a chunk of tree fern buried in the sphagnum? When I first read about repotting and getting rid of the old media, I tried teasing apart the tree fern to "save" the roots - with disastrous and similar results.

On the positive side - the older canes store quite a bit of energy. Unless they shivel and dry, there is always a chance that the orchid will multiply to survive. Watch for roots and sprouts at the nodes on the older canes. That's a long slow road, but can be interesting.

[BobInBonita]

Re-read your original post and realized my questions about timing were already answered - it was fast. Makes me lean more towards the Physan concentration or actual drowning. Was there ANY drainage or was it in standing water? The fact that you went 2 weeks without water and still had wet conditions pushes me more towards drowning.