Encyclia Bulbs Yellowing and Leaves Dropping
Q. My Encyclia cordigera suddenly, within a week, dropped two leaves and two pseudobulbs started to turn yellow from the apex to the base, with a brownish tone also. The affected pseudobulbs look shriveled. Right now there isn't any foul smell. What could be happening?
A. It looks like some sort of rot, as you obviously suspect when you say it has no foul smell. Are the yellowing/browning bulbs hard or soft where it is discolored? If the bulbs are hard, you would think perhaps Rhizoctonia root rot although that typically happens when the mix turns sour and of course your plant is on a mount. Are there any live roots attached to the dying bulbs? Your roots look good, so I'm guessing Rhizoctonia isn't the problem. It's probably more worrisome that the next two bulbs have leaves yellowing, so you would suspect that the infection, whatever it is, is travelling up the rhizome and travelling fast. The speed with which it's moving makes you think it's one of the water molds rather than Rhizoctonia, which is typically very slow to progress.
If it is one of the water molds, also called black rot, your friend is your shears, you'll have to cut away all the infected tissue. You can pour hydrogen peroxide over what's left and if you have one of the good fungicides like Subdue that is labelled specifically for Pythium and Phytophthora, drench what is left of the plant with it. It's really a shame cause the new growth is so nice and healthy and should have been in bloom soon.