Question
I just bought a mass cane from Lowe's today. It looks pretty healthy. However, I noticed a few patchy, dry brown spots on some of its leaves, as well as on other mass canes there. It had been recently watered. These mass canes were inside the store near a large, bright window.
Why do they have brown spots? I'll send a picture to  

Answer
Mitchell,

After looking at the picture that came separately I think it may be the Phyllosticta maculicola so I suggest that you spray the plant with a Lysol type spray entirely making sure you get the fronts and backs of all leaves.  This will kill any fungal infections if you spray it twice a week for 3 weeks. Consistancy is the key to getting rid of fungal infections.

I also suggest that you water it with distilled water, rain water or allow the city water to sit in an open bucket for 48 hours before using it to water the plants so it does not get additional brown spots because of the flouride and chlorine. Good luck.

Darlene

Mitchell,

I did not receive your picture. However I can telly that there are several causes for brown spots on leaves and it depends on exactly what the brown spots look like. Tip burn develops when the plant is too dry and the humidity is too low.  It can also be caused by an accumulation of boron or fluoride, or high soluble salts. If your city has flouride and chlorine in the water this may well be the problem.  Stop using the city water and you will get no more spots. You can water it with distilled water, rain water or allow the city water to sit in an open bucket for 48 hours before using it to water the plants and the chlorine and flouride will dissipate into the air.

When exposed to too much light, the leaves may become bleached in spots.  Move the plant away from the light source. This may be the problem since it was sitting next to a large window.

Fusarium moniliforme is a leaf spot disease caused by this pathogen often found in Dracaenas.  Leaf spots are round, raised, rust colored lesions with yellow halos.  Off-white spores appear at the growing point where the apex may rot.  Other symptoms include root rot, chlorosis, and wilting.

Phyllosticta maculicola is a pathogen that causes a leaf spot disease. In Dracaena it is characterized by brown leaf spots with yellow halos. With P. dracaenae, the spots are irregular, brown with purple borders and yellow halos, and appear on the lower surface of older foliage.

After reading this and examining the plant if you think that the cause is one of the last two then I suggest you spray the plant with a Lysol type spray entirely making sure you get the fronts and backs of all leaves.  This will kill any fungal infections if you spray it twice a week for 3 weeks. Consistancy is the key to getting rid of fungal infections.

Good luck!
Darlene