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Calcium sulphide or calcium polysulphide (lime sulphur)

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Calcium sulphide or calcium polysulphide may be used to control pear scab
Photo: Jardin botanique de Montréal (Lise Servant)

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

Product description

Calcium sulphide and calcium polysulphide are also known as lime sulphur. They are sulphur- and lime-based chemical compounds.

Pesticides with calcium sulphide or calcium polysulphide as the active ingredient are used as fungicides, insecticides and acaricides for treating trees and shrubs. They are available as concentrates to be diluted before use.

Target organisms

Products with calcium sulphide or calcium polysulphide as the active ingredient may be used to control such diseases as:

They may also be used to control mites and some insects (aphids, scales, etc.).

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

How it works

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

Application

The product must be mixed with water and sprayed on. The mixture should be shaken well before and during treatment. Thoroughly spray all parts of plants to be treated, without run-off.

The product may be applied during dormancy (in the spring, before buds open) or in lower concentrations during the growing season.

During dormancy, lime sulphur and mineral oil (horticultural oil) treatments may be combined, in accordance with the manufacturer's recommendations. During the growing season, allow at least 30 days between the application of lime sulphur and treatment with mineral oil.

The product should be applied when temperatures are below 27°C, in the early morning or late afternoon or evening, to avoid burning plants.

Precautions

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.

When applied during the growing season, the product may cause the foliage of some species, like plum trees (Prunus spp.) and some apple cultivars (Malus spp.), to turn yellow and drop off. 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.

The product may stain some surfaces, including painted wood, brick and stone.

Keep out of reach of children.

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