Woah! Great surprise!

[NYEric]

I'd cut the brown growth off and dust it with Captan. Good luck.

 

[The Mutant]

I'm concerned about that brown leaf. Is it crisp or soft?

Crisp. The lowest leaves started to die as predicted, but the fact that I let it suffer through a dry period didn't help (it was at the same time that I managed to blast my roebelenii for the very same reasons), as soon as I started watering properly again, the dying of the leaves stopped.

So what's left of this leaf is the least of my concerns, but I had planned to let it dry out completely before removing the rest of it.

 

[SlipperFan]

I'd remove the brown leaf. Carefully.

 

[SlipperKing]

Often the root tips can be reddish brown. To me, it's ALIVE!:evil: