Question
QUESTION:     TOM,
     Sorry I forgot to include this question with my last question. We have a yucca plant that gets a powder substance in the form of spots can you tell be what to do to get rid of them, unless this is common.
         Thanks
         Don

ANSWER: Hi Don,
Thanx for your question.  Can you be more specific about the powder substance on the yucca?  Is this a hardy, outdoor yucca or a houseplant and where is are the spots located?
thx,
Tom

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QUESTION:     Tom
     I assume this plant is a houseplant, the spots are all over the leaves.
         Thanks
         Don

ANSWER: Hi Don,
Thanx for clearing things up.  Take a look at this link and let me know if this is what you have.
thx,
Tom

http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=1160

---------- FOLLOW-UP ----------

QUESTION:    Tom
   I just had my wife look at picture of spots and she said no. Maybe I haven't been very clear. The spots,she says they look like spider poop, I ask her had she even seen spider poop and she said no. See what I have to work with. She can wipe the spots off with rag then they come back again, they look like powder.
         Thanks again
         Don

Answer
Hi Don,
Thanx for the additional information.  It sounds like it's just powdery mildew or some kind of fungus.  Does your wife water the plant with a spray of mist because if she does, this can cause white spotting.  Otherwise, I believe it is just a powdery mildew.  Always water this plant at the soil level or in the dish underneath the pot.  If it is powdery mildew, try neem oil on the plant.  Let me know if this works.  If it does not, we have an indoor houseplant expert here who might be able to offer some alternatives.

I hope this helps.
Tom