My phaius orchids new growth keep developing rot.

[doctorw]

I bought a phaius orchid a few months back and recently I moved it into a slightly large pot as it was root bound. Just before I repotted it I noticed some of the new growths starting to come out of the pseudo bulb had blackened and after I repotted it more growths have blackened as well as a bit of the pseudo bulb itself. What should I do? Its seems to start as a blue grey spot and spread from there. Also Ive only watered it when the substrates gone dry.

[Roberta]

First, Welcome!

Others on the Board grow Phaius more than I do ( I just have two)... but one thing jumps out at me, water... I wonder if it is reacting to lack of water... I keep this one quite wet. Unlike the epiphytic orchids like Phalaenopsis and Cattleya that need to dry out, this one is mostly terrestrial, and shouldn't get dry.

[doctorw]

The watering is what I'm not sure about as I've for the most part always kept it moist and watered it as soon as it began to feel dry

[Leafmite]

The only advice I have gotten was not to get water on the leaves or new growths (my Phaius is indoors in a window, not much air movement). I have been watering from below and carefully at the soil line.

When I see new growths rot like this, I always wonder if it might be Calcium deficiency. Calcium tends to strengthen the cell walls but it must be given to the plant before and during new growth.
Here is a pair of videos explaining the role:

Frontiers | Calcium—Nutrient and Messenger | Plant Science

Role of Calcium in Plant Culture | PRO-MIX Greenhouse Growing

Good luck!

[estación seca]

The few I've seen growing wild are always wet. They never get aywhere near dry.

[doctorw]

How would you recommend adding calcium? As some of it has now spread to the pseudobulb itself and the roots were fine.

[Leafmite]

Cali Magic, crushed oyster shell, (if outside, powdered milk--the milk will sour and smell), lime, etc. If you have a hardware store nearby, they would probably be able to recommend something. As it is spreading, you might need to look into a systemic fungicide.

Good luck!