The hydrolysis of sulphur in relation to its fungicidal activity

Abstract

1. It is suggested that the fungicidal action of sulphur upon the Erysiphaceae is due primarily to hydrolysis.2. The presence of alkali, which brings about an acceleration of this hydrolysis, should enhance the fungicidal properties of sulphur.3. An explanation is thus afforded of the inhibition of the fungicidal action of sulphur against the hop powdery mildew (Sphaerotheca humuli) by gelatine or saponin solutions when employed as the spreader and of the promotion of fungicidal action in the presence of soft soap and alkali casein solutions.4. Attention is drawn to analogies between the action of sulphur upon the mildew and upon copper.5. Current views relative to the fungicidal action of sulphur are discussed from the standpoint of the hydrolysis hypothesis.