120 GARDENING DIFFICULTIES SOLVED 



attack from thrips is usually the bringing of plants which are infested 

 with them into the vinery. For the destruction of red spider and 

 thrips you should fumigate with XL ALL on two successive evenings 

 when the weather is calm, of course closing down the ventilators to 

 prevent the escape of fumes. To destroy the mildew you should 

 heat the hot water pipes moderately and paint the pipes over with 

 flowers of sulphur made into the consistency of paint by added 

 water, sealing up the vinery as closely as possible, as in the case of 

 fumigating. Do this on two successive evenings of calm days. 

 Afterwards do all you can to encourage healthy growth, by keeping 

 up a moist and congenial atmosphere in the vinery. 



Fumigating" with Hydrocyanic Acid Gas 



Q. White fly is a nuisance in my greenhouses. I am thinking of 

 fumigating with hydrocyanic acid gas. In the directions it says : 

 "After an hour the doors should be opened, also the ventilators, 

 but only if they can be opened from the outside. In no circum- 

 stances should the house be entered until the next morning after 

 ventilating." Most of my houses are span-roofed, with top venti- 

 lators and one at end. I could arrange to open the end one from 

 outside, and, of course, the door. Would this be enough 1 How 

 long would it be necessary to ventilate 1 Will white fly live all the 

 winter in cold houses or frames 1 E. M. t Chepstow. 



A. If you were to open the end ventilator all night it should be 

 sufficient to clear the house of gas ; but it would be just as well to 

 stand the door open for an hour in the morning. When using it I 

 could only open the side ventilator of the houses, and I always 

 found them clear in the morning. Great care should be exercised 

 when using the above fumigant. The door of the house or houses 

 should be securely fastened, and a notice on it warning anyone from 

 entering the house ; one inhalation of the gas will prow fatal. If 

 only troubled with white fly, I would advise fumigating with 

 XL ALL compound, or any of the other good compounds offered 

 for sale, as white fly is very easily killed. Of course, to get rid of 

 it one must fumigate several times, as fresh broods hatch out. It 

 is usually troublesome during autumn, and should not live during 

 winter in houses or frames, unless they are kept hot and close 

 The proportions I have used per 1,000 cubic feet are 2| oz. cyanide 

 of potassium, 4 oz. fluid ulphuric acid, 8 oz. water. Use a 

 shallow earthenware vessel, and be careful to add the acid to the 

 water, not the water to the acid. 



