Kitchen Garden Forum

Although its chief uses are in the preparation of sulphuric acid, sulphur trioxide, and sulphites, sulphur dioxide also is used as a disinfectant, a refrigerant, a reducing agent, a bleach, and a food preservative, especially in dried fruits.

I think it is used in the brewing industry as well.

Sulphur dioxide from burning sulphur should be treated with great care. It dissolves rapidly in water to form sulphuric(IV) acid (formerly sulpurous acid). This water could be moisture in the air, in your nose and lungs, surface of your eyes or on the surface of slugs, amphibians, worms and so on. So it is unpleasant and very irritating stuff. Great care should be taken to avoid breathing it in particularly if you have any respiratory conditions.
Sulphuric(IV) (sulpurous) acid is not quite in the same leaque as the better known sulpuric(VI) acid used in car batteries for example.
When used properly it is a very effective disinfectant - bit like using a sledge hammer to solve the pest problem.

John

Thanks for that.

Are there any "safe" alternatives that you are aware of?

Has anyone got any experience with "garlic candles" such as http://www.greengardener.co.uk/product. ... =13&cat=25

Sulphur candles can no longer be legally sold, I understand. This year I bought a 'greenhouse fumigant' (can't remember the name) and used that, but it was only an insecticide not a fungicide which I really wanted. But as our unheated greenhouse is always slightly open on all side, even on the foulest days, moulds will hopefully not be a problem.

I used a sulphur candle once. Never again ! The acid formed sets every bit of exposed metal fitting corroding.

What I do find helps is a really good clear out of debris, and avoid any temptation to grow overwinter salads in there - these provide a host for pests and mould and are usually pretty miserable anyway.