<< I'm assuming the particular formulation being used is designed to bind to soil and thus lessen the chances of damaging the wrong plants. Treflan normally lasts a month or two in soil, so I wonder about applying it several times... was he following label directions? >> Kay, He applied twice in his 6 month growing season. We are in California. Instructions say to use more often than he did. Thanks for the info and links. I will study them all. It is so difficult to know what is safe these days. Mary-Anne