Pat from Oviedo, Fl writes
While the label for Organocide 3-In-1 Garden Spray Concentrate does not specify fungus gnats directly it does say it kills the eggs, larvae, and nymphs and the adult stages of over 25 soft bodied insects so it could kill them. Normally just allowing the soil to dry out completely would be enough to kill anything in the soil. You should read our "Getting Rid of Gnats" article that explains how to treat fungus gnats.
Answer last updated on: 02/25/2015