Dendrobium Leaf Drop & Blotchy Leaves

[DSDNYC]

Please forgive me, I posted a few days ago in the beginner section, but thought I might find more help here.

My Dendrobium Yellow Chinsai 'Little Joe' was doing fine this summer, it's third year. By late summer, I noticed lots of small black spots on a number of leaves and suspected a fungal problem (I had two other orchids (Psycopsis and Phaleaneopsis) that also suffered from a fungal problem at the time- they died too much water and lack of ventilation in a bathroom window) I repotted and treated with Phyton 27. Things seemed to improve, but the orchid still has a number of blotchy yellow/green leaves instead of solid green- too many blotchy leaves.

With cooler weather, I have withheld water like I do every fall/winter except for a sip. This year, any water, and large numbers of leaves instantly turn yellow and drop. I want to think that the leaf drop is due to watering during cool weather. but the blotchy leaves don't look normal. I've seen this orchid at it's best and something is definitely wrong.

Advice appreciated

David

[glengary54]

David - your Dendrobium Yellow Chinsai is made up of three species that all require a cooler drier winter rest period with very bright light. Obviously as you reduce water over the winter you are going to experience some leaf drop. If the leaves are turning yellow and then falling off, that is normal.

The black spots with a yellow halo around them is a fungal infection, as long as there is a yellow halo, the infection is still active. Spray with a fungicide. The black spots will not go away. Hope this helps!!

[DSDNYC]

Thanks Glen, much appreciated.

[DSDNYC]

Glen

How often should I spray with fungicide?

David

[glengary54]

David - if you can manage to relocate it from the non-ventilated bathroom into an area with bright light and normal air movement, once should be enough, if it is going to stay in a stale,damp and humid environment like most bathrooms, I would spray it once a month over the winter.

[DSDNYC]

Glen- Thanks again for the advice. i moved the orchid to a bright light normal air movement spot a few days ago, and today, I sprayed it with a fungicide. The lack of an exhaust fan in that bath has proved to be a much bigger issue than I originally thought. Thanks for all the help

[Paul Mc]

I'd like to add that one of my Dendrobiums also experienced extensive leaf drop last year as well. I noticed that the more I watered it, the more it dropped leaves. It was also in bloom from early August until about February if memory serves me correctly. For me, it was an issue of the potting media being wrong for the plant, thus causing roots to die. However, this year the same Dendrobium has spiked at the exact same time it did last year and is repeating the pattern, but without the leaf drop thus far.

Just wanted to point this out in case the potting medium might be an issue as well. Of course, we have hit the time of year as last year when I started experiencing my issues. I almost lost it last year, but luckily solved the issue before completely loosing it.

[DSDNYC]

Thanks Paul- i repotted this orchid last Spring, but that's good to know. I think that if I can lick the fungal issue things will improve.

David