Question
I have a stromanthe burle marx plant  and most of the leaves have small brown spots on them.  I have it in a pot and sitting on a tray of pebbles which I add water to when dried out. Is this a disease or just bad care

Answer
Hi Cynthia,

I would encourage you to look at the roots and make sure that they are abundant and light colored.  If they appear brownish or sparse, the problem could be a root rot.  Unfortunately, here is no cure for a root rot problem for this type of plant.

If the roots look ok, then I suspect that the problem is bacterial leaf spot.  If you remove one of the leaves and hold it up to the light (bright light or sunlight), look to see if there is a slighly yellowish halo between the healthy and brown areas.  Often this yellow halo area will not be noticed on the plant, but you can see it if you hold it up to the bright light.  If you see this, it would suggest bacterial leaf spot.  

If this were an outdoor plant with bacterial leaf spot, I would suggest that you try to use scissors and remove the brown areas.  You would want to disinfect the scissors between cuts by spraying with lysol or dipping in a bleach solution (1 part bleach to 9 parts water).  This would help prevent spreading the problem.  All the sick foliage should be discarded.  You would want to keep the leaves dry and treat with a fungicide containing copper hydroxide or copper sulfate.  It would be best to repeat this application in about 7-10 days.  After that, you can wait to see if there is improvement.  If the infection is light, it may be possible to prune the disease out.

If your plant is an indoor plant, it is not safe for you to treat it with chemicals indoors.  I am not aware of any products that can be used on a house plant for this problem.  You may be able to move your plant outside temporarily.  

When you examine the plant, if you do not find the halo, it may have something to do with other cultural problems.  It might be related to fertilizer, soil pH, amount of water or light.  It sounds like you are taking good care of the plant, so I am leaning towards the bacterial problem.

I hope this helps you figure out what is going on.  Let me know if you need additional assistance.

--Jen