Copper and sulfur are two minerals long used in agriculture as fungicides and insecticides. Their use in organic farming is permitted but only in reduced doses, since their effectiveness is not associated with total safety, as they are products that can become toxic for man, animals and the plants themselves.
For decades sulfur has been used as an insecticide and fungicide; on the one hand against cochineal and mites, on the other it is the typical fungicide used against powdery mildew and the bubble. In reality its range of action is quite wide, since besides being useful in eradicating some insects and mites, it is very useful in orchards against all the fungal diseases that most commonly afflict fruit plants, such as oidium, corineum, scab, bubble, monilia and fumaggini of various origins.
This mineral is irritating to humans and animals, if it comes into contact with the skin or if inhaled; It is therefore advisable to use it on windy days and to cover itself adequately; it can also be harmful to plants, although its phytotoxicity is particularly evident when used on plants with already well-developed buds that are ready to hatch, on greener vegetation. It is therefore advisable to use sulfur only during the autumn or winter, and in a limited manner during the summer. It shows particular phytotoxicity in case of strong temperature changes, as can easily be verified at the end of winter or spring.
As mentioned before, the use of sulfur-based fungicides and insecticides is practiced mainly on fruit plants, possibly at a distance of 15-20 days from treatments based on mineral oils, and waiting at least 30 days between a treatment based on sulfur and the next.
Copper and sulfur: Copper
Copper is also a mineral that has always been used in agriculture, particularly in viticulture, against the development of downy mildew. The use of copper, in any of its forms, is strictly controlled in organic farming, due to the toxicity of this mineral for humans, animals and plants; also in this case it is advisable to use copper particularly during autumn and winter, since it can damage the buds and the green vegetation of the plants.
It is used in particular in vineyards, orchards and horticultural crops; fights many fungal diseases, such as downy mildew, blister, scab, corineum, dry ache.
Copper and sulfur are used in combination orchards in the Bordeaux mixture.