Basal stem rot

[pheli]

It looks like a fungal infection and occurs on the basal of my dendrobiums. I was told it was black rot, causing by Pythium spp. and hence I also tried some specific fungicides on it, but they did not work well.
Could you please give me any idea about how to cure it or does anyone know what cause it?
Thanks in advance.

[weiss]

It looks like your plant is too close to the moss. Either you watered the crown and the moisture was trapped inside the crown, where it rotted from the inside of the stalk, or the humidity from the moss could have caused the problem?

[pheli]

Steve, I adopt moss to grow several kinds of orchids. But the disease only occurs on dendrobiums. The rot initially infects the out layer of the stem, and then gradually affect the inner core. While the core is infected, the plant usually dies. The dendrobium showed above is a lucky one because the rot stopped, and the new p-bulbs showed no sign of infection.

The rot usually happens in our humid spring and summer, especially during May showers and after the typhoon hitting.

[weiss]

Have you used a synthetic fungus treatment? Also, i understand Dend. like to be a little dryer than many plants and like to be potted tightly.