I use 60% water, 20 % alcohol, and 20 % regular 409. I put this in a spray bottle, and spray all leaves.I spray once a week if the orchid has scale...every week, once a week for three weeks. If it is mold or mildew, I dip the plants roots in nine parts water, to one part bleach. Won't hurt the orchid...let it dry on the plant The 409 spray was given to me by a grower in Hawaii...BettyE.