Optimised sulfur based pesticides using sulfosuccinates alone and in combination with an anionic surfactant to improve the retention of sulfur on plant vegetation from aqueous spray solutions. The pesticide may be sulfur, which may be administered as fungicide. The succinate may be a monoester or a diester, preferably dioctyl sulfosuccinate. A claimed formulation comprises sulfur, a sulfosuccinate and an anionic surfactant selected from, phosphate esters, sulphonic acids and their salts, monosulphate esters, naphthalene sulphonic acid derivatives, sulphonated vegetable oils, sulphonated esters of natural fatty acids, carboxylic acid derivatives, alkyl substituted succinic acid and polycarboxylic acid salts. A claimed solid formulation comprises from 25 to 85 wt% sulfur, from 0.125 to 30 wt% sodium dioctyl sulfosuccinate and from 0.125 to 30 wt% sodium lauryl sulfate. The solid formulation is delivered to the vegetation as an aqueous spray solution. The formulations are used to prevent or reduce fungal diseases, such as powdery mildew or Septoria diseases on fruit, vegetables, ornamentals, grapevines and cereals, e.g. wheat.
