I'm not sure if this is what you might be seeing. I can't access your pictures. I know this mildew has been traveling quite a bit this year. http://vegetablemdonline.ppath.cornell.edu/NewsArticles/BasilDowny.html#Report Best of luck- Here is a link that might be useful: Basil Downy

it would be nice to see a picture of the top surfaces of the leaves as well as the bottom. But just based on what you have plus that little bit of the top surface showing on the leaf in the middle, I think I can narrow it down to two(?) diseases. Either basil late blight or basil downy mildew, which are likely two names for the same thing... Not to be confused with late blight of tomato, an entirely different disease This post was edited by nickl on Wed, Aug 28, 13 at 15:25

They probably came straight from a greenhouse They need to be hardened off -- in other words, slowly acclimated to the outdoor world of bright light, sun, and breezy to windy days.

I second Ray Rose. That tree will die. Didease can spread. Not good situation for you or yout tree.