I'm not sure of the cause but this type of spot is nothing to worry about. The types of spots that should cause concern are soft or wet spots which are generally bacterial in nature. Also a yellow spot such as the one you are seeing that continues to radiate outwards is often a fungal infection and these can be difficult to deal with. Two good things to keep on hand are peroxide for bacterial rots and cinnamon for fungi related problems. Garden sulphur is also great for fungi infections.

The spot on your plant looks like something that could happen if a water droplet were left on a leaf during a period of very bright light. Either way it does not appear to be spreading.

Mike

Thanks for that reassuring info. I was afraid it was the beginning of a something bad. I usually treat fungi with garden sulphur and have heard of using cinnamon but have never tried it.

Mike: So do you just rub cinnamon on the leaf?

Susan

Yes you can sprinkle it on the leaf or better yet do what was suggested by another forum member a while back, make a paste of cinnamon and water and apply that so it stays in place. Cinnamon works surprisingly well against fungal infections.

Mike

Many thanks!

Susan

Karyn,

I agree with Mike. I have several species that seem to get these purple spots, and especially on the leaf undersides. It seems to have no impact at all on the plant health. It would be interesting to know why some species do this. I think I'll do a bit of research and "brain-picking" to see if I can find out what causes it...

Denise in Omaha