Hello. Residue Test: Mix some up and spray on some flat glass. Let dry. Run your finger over the area. Feel your finger, smell your finger. Is there anything there that can get into your smoke. Is there is a lot of residue is there next to nothing. You decide if you want to use it. I've used this on cactus to kill bugs, Please test on lower leaves before you use on everything. Half isopropanol alcohol and half water in a spray bottle. And some dish soap, 4 or 5 drops. The alcohol kills by drying them out, eggs too. The soap gets into their lungs and coats them. But it makes the water slippery and it runs of quickly. I haven't had need to try the mix myself or flowering cannabis plants. My main concern is: will the alcohol dissolve the THC crystals? So test it first, and catch the runoff, and let dry. When dry, test with your finger to see if it sticky. Don't get much on their roots, the plants can look droopy (drunk) for a day or two. Tilt the pots or cover the rot area with plastic. Good Luck. Chuck.