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Sulphur may be used to control powdery mildew
Photo: Ministère des forêts du Québec (Lina Breton)
Uncinula adunca

The information below is intended only as a guide. Always read product labels carefully.

Product description

Sulphur is a mineral extracted from the ground. It has been used for hundreds of years in making fungicides and acaricides for treating ornamental plants, fruits and vegetables.

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.

Target organisms 

Products with sulphur as the active ingredient may be used to control such diseases as:

They may also be used to control mites.

NB: The product label lists the plants on which the pesticide may be used, along with the target organisms. 

How it works

Sulphur inhibits the germination of spores (reproductive cells) and affects the growth of fungi. How it works on mites remains unclear.


The product is most effective when used as a preventative or as soon as symptoms appear.

Depending on the formulation, the pesticide may be dusted or sprayed onto plants. When the powder is diluted in water, the mixture tends to separate, so it is important to shake the sprayer well before and during treatment.

Allow at least 30 days between the application of sulphur and treatment with mineral oil (horticultural oil).

It should not be used at temperatures of 24°C or higher.


The product 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.

It may be toxic to some plants (phytotoxic), including cucumbers (Cucumis sativus), melons (Citrillus lanatus, Cucumis melo), squash (Cucurbita spp.), Boston fern (Nephrolepis exaltata 'Bostoniensis'), some cultivars of grape vines (Vitis spp.) and pear trees (Pyrus spp.). If in doubt, it is best to spray a small area of the plant and wait 24 to 48 hours to see how it reacts.

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.

Keep out of reach of children.

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