Yellowing Leaves
 

Hi There:

As you may recall, I had a bug problem which I took some unfortunate actions to try to address. I rinsed, trimmed roots, and repotted them, tossing two with the worst bugs. Since the repotting, I haven't seen any bugs, but the dendobriums haven't bounced back. It seems like they have shriveled in the canes, and leaves have been slowly turning yellow and dropping off. They were in their own mixes from the vendor, and I didn't have small chip bark or moss to replace it, so I put them into a mix of large bark mixed with medium lecca, small and medium charcoal, and small perlite, and small stalite. Since then, I've watered 2-3 times a week, like I had been and they liked it before the repotting, using some Superthrive rooting hormone in some of the waterings to encourage new roots. Any idea what's wrong? They never lost leaves over the winter.

I have a lawesii and a victoria reginae.
Attachment 69893

Attachment 69894

Regards,
Kara

Fresh bark will not hold moisture long - it's possible that it's drying very quickly, and plants aren't getting enough water. Whenever I have newly repotted plants in medium bark, they need to be watered more frequently for a couple of months. Soaking the pot for 20-30 minutes will help some, but will still need more frequent watering.

I'm not sure about these two species - some Dens really dislike their roots being fussed with, so that could be another possibility.
(I do have a victoria-reginae, but can't remember if it sulked after being repot when I got it)

So I guess I just need to aggressively up the watering schedule for them, probably to every other day. I'll give that a try.

They look like they are getting to much water. Shrveling canes and yellowing leaves are signs of too much water or more likely staying too wet. Roots aren't going to form in a stale environment. Acids start to develope and stunt or stop new root tips from growing. Once a plant gets to a certain point after trauma it suffers too much and stops it's growth. I would treat them as if it were getting to be winter and stop watering them so much. Tell you what, stop watering one of them just misting it daily or as often as you can. Water the other one as oten as you like. Put them both somewhere that is warm and sunny. See which one comes back. The one that you cease watering, don't let it dry out completely. Just water it sparingly. Just barey damp. No more than that.

Thank you Sonya, thank you James. I decided to try Jame's suggestion, water one more often and more soaking watering than just a quick flush, the other one gets watered no more than once per week. Both get misting. I'll let you know how they do. So far, no real changes.

And the answer is.... no answers. ;) They are both continuing to lose leaves. So it occurred to me that maybe these species are supposed to lose leaves, and if they came from the southern hemisphere, maybe this is their winter. I'm going to ask the Dendrobium Alliance for information.

Actually orchids don't know when the other half of the world is currently in winter or summer. It is summer here where they live so they should be acting as though it is summer not winter. Something else is causing your problems. The individual plants you have might not have ever been in the southern hemisphere at all. They most likely are seed grown plants that have lived their whole lives in the US. For example, if you took a Cattleya species that naturally grows in brazil and it lived in brazil then it was brought to the states it would adapt to grow in our seasons. So they would bloom/grow in their bloom/grow season whether they lived here or in Brazil. Orchids follow the seasons/weather not the calendar.

I don't grow these species so hopefully someone will have an answer for you. I think the culture isn't right and they didn't like the repot. I hope they recover for you! Good luck!

Thanks Wynn! I hope so.

I Googled these species and they do lose their leaves on old pbulbs at some point but I don't know when they are suppose to.

I'd look at the roots - only way to get an idea what's happening there. If they have been over-watered, roots will be squishy and rotted. If under-watered, dried out. With the media you have used, I think over-watering would be hard to do at this time of year, especially with fresh bark - but, could be :dunno:

I'd use a skewer in the media to check for moisture in the media.