The fungicidal properties of certain spray-fluids, VI

Abstract

1. The action of various forms of sulphur—ground sulphur, flowers of sulphur and colloidal sulphur—as fungicides against the hop powdery mildew (Sphaerotheca Humuli) was tested in a number of experiments.When ground sulphur or flowers of sulphur was wetted by a soft soap solution and applied to the mildew patches in the form of a spray, the fungicidal action was always very marked and, under the conditions of the experiments, became complete with suspensions containing 5 gm. sulphur per 100 c.c. of 0·5 per cent, soft soap solution. Owing, however, to the settling of the sulphur particles during the process of spraying, the amount of sulphur actually applied to the fungus was not strictly in accordance with the strength of the suspension.2. Striking differences in fungicidal action were obtained when gelatine or saponin were used in place of soft soap as a spreader. Spreaders of an acid nature, viz. gelatine and saponin, inhibited the fungicidal action. With alkaline spreaders other than soft soap, e.g. lime casein and soda casein and the dry-mix sulphur lime, the alkaline reaction favoured the fungicidal action of the sulphur.