Sulphur (S), is probably the oldest and best known insecticide/pesticide in use. It has been used for over 2000 years in making fungicides and acaricides. The Greek poet, Homer, described the benefits of "pest-averting sulphur" 3,000 years ago. It is a mineral extracted from the ground.

Pesticides with sulphur as the active ingredient are available in liquid and powder form. Some products are ready to use, while others must be mixed with water before use. Its primary use is to control powdery mildew, rust, leaf blight and black spot. Spider mites and thrips also are susceptible to sulphur. Sulphur inhibits the germination of spores and affects the growth of fungi. How it works on mites and thrips remains unclear.

Sulphur should not be used at temperatures above 24°C and is incompatible with other pesticides. There should be a break of at least 30 days between using sulphur and applying spray oil as Sulphur reacts with the oil to cause phytotoxicity.

Sulphur is non-toxic to mammals, but may irritate the respiratory tract, skin and eyes, so it is best to wear a mask, gloves, long sleeves and pants and goggles when applying it. Do not use near any body of water or wetland, or dump any pesticide or rinse your equipment there, as this will contaminate the water. Never dump pesticides down sewers

Lime Sulphur is one of the best insecticides/pesticides to use, if you do not mind the smell.