They probably mean a sulphur candle rather than a smoke bomb. This is a slow burning tin of sulphur that produces sulphur dioxide. In moisture sulphurous acid forms and kills all life within the greenhouse. I used one this winter and it worked.
All the galvanised fittings like Vine eyes got ruined by the aggressive rusting that occurred however, and our garden was 2C warmer due to local global warming!! ![laugh :lol:](https://chat.allotment-garden.org/Smileys/green/laugh.gif)
No I can asure you they were called Smoke bombs, and did a great job. I have used them many times in the past. But I know a lot better now. In thoses days no one knew about the danger of widely used chemicals.
My Dad used to spray are beds with DDT will we were in them,(To get rid of bed bugs) Using a Flit Spray. I dread to think what that did in the long term.
It was common to burn Pure Nicotine in the green house, a deadly poison. Plus the use of extremely explosive weed killers.
In fact its a wonder IM still around.
![wink :wink:](https://chat.allotment-garden.org/Smileys/green/wink.gif)