I had something growing on my basil plants one year that I can't identify. It was a white goo, something like phlegm, but way too much to come from a person, even if he had a major cold. It only grew on the basil, not on the surrounding plants. And this was something called bush basil. The standard generic basil was untouched. After I cut of the offending branches, it never came back. This was maybe 10 or 12 years ago. Ive never seen anything like it since. Any clues?