When mixing these two it is safe to spray plants.....right? I have been using razor burn for 1 week now, and am afraid to kill small plants or bushes. So i bought ronstar. I know ronstar is a pre and razor burn is a post. Should i just spray ronstar in bushes/plants with weeds that are post, or is it safe to mix the 2 together? I.e juniper, sheplara's, fire bushes, holly boxwood schillings, indian hawthorne's.