Question
I have brownish-black spots developing on the leaves of my night blooming cereus.  What is it and how do I treat it?
Thanks. Melody

Answer
It sounds like you may be overwatering the cactus, causing a fungal or maybe a bacterial leaf spot.  The plant requires very little water when grown in a pot.  It also doesnt require much sunlight either.  A little later in the spring you can put the plant in low to medium light outside (provided you dont already live in Arizona) and wait for the spectacular bloom event.  After it blooms, put it back into dormancy once again.  Do not repot often.  I would suggest you make your own fungicide by taking one tablespoon of baking soda and one tablespoon of light cooking oil and mixing with one gallon of water (make smaller quantity if only one plant to spray).  Spray once every 3-4 days for a few times and see if the brown spots begin to look dried up.  You may need to repeat this a few times during the year.  If all of this sounds wrong, please respond back and we can try a different route.  Good Luck.