GH Defguard Biofungicide / Bactericide Pint (12/Cs)In Store Location: @E9 GH Defguard General Hydroponics Defguard is an OMRI listed biofungicide and bactericide for use in organic gardening that's effective against a variety of pathogens, particularly botrytis and powdery mildew. By colonizing the root hairs, Defguard prevents the establishment of disease causing fungi and bacteria to protect against anthracnose; bacterial leaf blights; spots and specks; black mold; black spot (on roses); brown spot;