Wettable Sulphur (also spelled sulfur) is a fungicide and insecticide suitable to be used in organic gardens and has an exceptionally low level of toxicity. It is used to control mites and a range of fungal disorders including powdery mildew, rust, and brown rot. As an insecticide, wettable sulphur can be used to suppress mites especially the red spider mite and the erinose mite. It is safe to spray on vegetables, ornamentals, citrus, and vines in your home garden. Sulphur is acid and should be used for acid loving plants such as citrus and tomatoes, but not on soft and alkaline plants such as cucurbits. As well, apricots and raspberries should not have Wettable Sulphur applied to them
Wettable Sulphur is applied as a foliar spray. The mixture is 3 grams (approx 1 teaspoon) to a litre of water. This mixture should be sprayed on the upper and under side of foliage, giving it a good drenching. To avoid adverse effects on the important soil fungal activity, other agents such as weed tea (comfrey or stinging nettle) or milk spray should be used in rotation.
Do not apply Wettable Sulphur when the temperature is hot (over 24 degrees C). Also do not apply 21 days after or before using an oil based spray.