Sulphur treatment of soil and the control of wart disease of potatoes in pot experiments

Summary. In a series of pot experiments on potatoes grown in an acid soil artiftcially infected with the wart disease fungus, treatments with sulphuric acid and various combinations of sulphur and calcium carbonate, yieldmg a wide range of soil reaction, gave almost complete freedom from infection when the acidity of the soil had been raised to a very high value (pH 3.4 or less). Heavy dressings of calcium carbonate, alone or with sulphur, giving a soil reaction of pH 7.5 or more, also reduced infection. The fact that partial and even, in one experiment, complete suppression of disease was obtained at lower acidities, where the effect on the disease was not closely related to the degree of acidity, supports the tentative conclusion already drawn from field experiments that sulphur in controning wart disease does not depend entirely on its effect in raising the acidity, but has also some other mode of action. Whether this toxicity which sulphur exerts apart from its effect on the acidity can be enhanced sufficiently to be of any practical value requires further investigation.

RESP-00526