Laelia anceps 'Mendenhall' - black spots on older bulbs
 

Greetings

I recently purchased a large L anceps Mendenhall, and it has black spots on leaves and bulbs. I have other anceps on which I've seen this, and in the past I've cut them out of leaves, done minor surgery on the bulbs (digging out the rotted black area and treating it with 100% Physan) and it hasn't advanced. However, I've never seen it to this extent.

I assume it's fungus rather than bacteria since it never has spread rapidly. Given the extent of it, I'm not sure whether a systemic treatment (I use Phyton) would do much.

So - diagnosis? treatment?

As you can see it's a big vital plant, but I know how quickly that can go south when these nasties aren't controlled.

p.s.
 

In case you haven't seen this strain before:

Last year I purchased another of this strain, also in spike, here is what the blooms looked like (before I left this plant and some others outside during a cold snap lost all flowers, buds, spikes, and several pseudobulbs on all my not-cold-hardy-enough orchids. Orchid enthusiasts are gluttons for punishment! :( )

Some of my catts came with little black spots. If they are dry I would leave them alone. If they are moist and spreading then you know what to do. Many people say that you will get black spots if your plants are low on mag and calcium.