Question
Hi Sir,
I have brownish-black spots developing on the leaves of my dragon fruit plants (pitahaya plants).  What is it and how do I treat it?
Thank you very much.

Answer
That is a fungal problem, usually caused by wet leaves at dusk; fungal spores incubate in the droplets. Get a product called Daconil,,,,,(Home Depot, Lowes)...its a broad spectrum fungicide and follow the directions on the label. It should clear it up,,,what you will see is the new emerging leaves will be devoid of the infection, while the effected leaves will just yellow and fall off. Nick