I don't know exactly what this could be, but I would have checked for creepiecrawlies, such as thrips. You may need a magnifying glass and good light to see them if they are there.

Where do you live?
Likely physiological/environmental.
Is it near a window?
Prevailing temperature?

And please post a pic of the entire plant.

Whole plant

Healthy leaf

Another example of a leaf with the brown spotting

The leaf with a white spot (there is only one like this in the entire plant)

Thank you for your replies so far.

jean001a,
I've posted a few additional pictures above. As you can see, the plant is in an office setting. It is near a north-facing window, which sometimes has the sun reflected into it a little more directly by the opposite office tower. There is warm air that blows from the radiator below the window and air also blowing some of the time from the ceiling, such that the leaves on the plant are usually slightly swaying no matter where I put it. The average temperature is mid to high 70s F (23-25 C). The pot that the plant is in is relatively small, but it seemed to be pretty happy in it for a long time.

In case this is some sort of a bugs/spiders/mites/etc issue, I was thinking of doing two things to prevent spread:
1) Removing affected leaves (about 1/4 of the plant). I don't want to do this if there is a reasonable possibility of these leaves healing themselves.
2) Spraying the rest of the plant with a mixture of distilled water, a drop of dish soap, and a teaspoon or two of olive oil. My concern with this is whether it may do more harm than good, and also whether the plant will dry properly if I do this indoors. If applying this kind of mixture is a good idea, would it be better to apply it onto the leaves with a cloth rather than a spray bottle? Or use a different formula?

Thanks very much in advance for all suggestions.

This post was edited by Jason17 on Tue, Dec 3, 13 at 7:02

I have a general rule of thumb where I don't treat any "bugs" unless I can see and identify them. There is no point in threatening your plant with possibly toxic treatments if you can't see an agent causing it.

Are the spots mostly on new leaves, or older leaves?

Some dracaenas are sensitive to flouride compounds in the water. I'm not sure the spots would look like yours, though.

Has it been repotted recently?

I read an Fla extension article on dracaenas intended for producers which listed potential problems and one of them was wind burn.But I would think wind burn would be more a browning edges problem. It doesn't seem like it would be a disease problem if the plant is always in a breeze. There are a lot of fungal problems plants can get if they are in cool humid stagnant places.

The white spot just looks like someone inadvertently flicked something toxic on your plant while they went by, or mechanical damage.

No plant is happy forever in the same pot with the same potting soil. if you haven't repotted/replaced the media in a while you might consider that.

Could it have gotten sprayed by Windex or something yucky by the cleaners?

I am sure glad I don't have to work at an office with prevailing temps of 75-80 degrees. Whew!

Not bugs or disease,
As was said, environmental. Don't know precisely what from this distance.

Fluoride tox looks quite different.

Thank you for the replies.
So other than considering repotting, what should I do?
Should I remove the affected leaves?

To answer aseedisapromise, the affected leaves are somewhat concentrated on one side of the plant (the one facing the camera on the whole-plant picture), but on that side, the spotted leaves run from top to bottom, so both newer and older leaves are affected.

This post was edited by Jason17 on Wed, Dec 4, 13 at 1:12

I'm a bit late to the conversation. Judging by your photo and your description of the leaves only being affected on the one side, is it possible as aseedisapromise mentioned, that it got sprayed by Windex or something yucky by a cleaner? I would imagine certain chemicals would cause damage to plant leaves.

Planto

Planto, It's highly unlikely, as I clean the office myself, not using company cleaners.

Whatever the cause is, even if it's not a disease that's going to spread, I'm still wondering whether the affected leaves will inevitably die, in which case, wouldn't it make sense to remove them now so that the plant doesn't waste its resources on them and so that it grows more new leaves instead? Not sure if this is how it works though.

Jason17,
I'm honestly not sure what is going on with the leaves, but if you want my personal opinion (as if it were my plant)... if it's not a disease (which I can't rule out) and it's not going to spread, I would just leave the leaves alone. If they want to die on their own, let them. If they don't die, you have a plant with character (I had a Math teacher who told a fellow student that scars were a form of character... makes you unique).

I'd hate to cut the leaves off if they would have stayed alive and attached to the plant if I had left them alone.

If you notice them dying, that's a different story. In that case, I'd say it's safe to say go ahead and remove them. Hope that helps, I know it doesn't tell you what's wrong with the leaves.

Do you mist the plant with water at all?

Planto

Planto,
I haven't misted it for a long time. Should I? I've read a lot of people suggesting on other threads to add a pinch of dishsoap, mineral or cooking oil, and/or alcohol to make a sort of organic mixture for spraying - that's why I was asking whether to apply something like that. Or should I just mist with plain water?
Another thing that generally gets mentioned a lot in other threads as the cause of problems is root rot or fungus, often due to overwatering but also for other reasons. That's why I was concerned that if by chance that is my problem, spraying with water indoors may make it worse.

This post was edited by Jason17 on Wed, Dec 4, 13 at 17:40

Hey Jason, I did not see you mention how long that plant has been in the same mix and what kind it is..I also wouldm like to know if the mix is composted and whether it drains quickly?

If not, as far as cultural conditions and your fertilizing/watering habits, but based only on odds, my first guess is you need to take steps that will eliminate both soluble salts AND the possibility of root rot if you DO water properly.

Salts can be the death of most plants and show up symptoms in many ways including this...It did on mine in years past..

Mike

Jason,
I don't know much about mixtures used to treat things, but I think I remember you mentioning you didn't want to treat it if you weren't sure if anything was wrong. I can't say anything with regard to the mix mentioned, I haven't sprayed anything on my plants other than fish emulsion. I'm sure I read somewhere misting with water doesn't really do anything to raise humidity, so I'm not sure you need to mist with water. I'll let you respond to meyermike about your soil, etc., but if this were my plant, with respect to the spots, I'd wait and see if the leaves die or if the spots spread. If nothing happens, I guess your plant is okay.

Planto