As I gather it, there are a variety of slightly different proteins, termed harpins, which have a similar effect to the original Messenger harpin and Employ H&T is one of these. The Employ H&T ingredient is termed alpha,beta harpin and it's isolated from a different species of bacteria. While uncovering this fact, I was surprised to learn that none of the harpin-derived products is organic certified.

Here is a link that might be useful: EPA Registration Document for Alph,Beta Harpin