Copper dihydrazinium sulfate or Omazene has been used for control of mildew on roses and several other flower crops. The material is quite effective against mildew and blackspot of roses. Omazene might be used for control of other fungus diseases on fruits and vegetables as well as ornamentals. Omazene appeared quite toxic to chinook salmon during the first 24 hours of exposure; concentrations of 0.75 p.p.m. and over produced mortalities.