THE commercial acaricide and fungicide currently offered as ‘Karathane’ has been shown to be one of the few substitutes for sulphur for the control of powdery mildews on a number of crops. The active ingredient is stated to be 2 : 4-dinitro-6-(l-methyl-n-heptyl)phenyl crotonate, although some of the phenol is usually present in the free state.