338 REroKT of the Horticultural Department of the 



THE FORMULAE. 



The following formula is recommended by Sirrine for general 

 use in fumigating well-matured dormant nursery stock. For 

 each 100 cubic feet of space in the room use: 



Formula for Well-Matured. Stock. 



Fotassium cyi^L^'de, 98 to 99;^ pure 1% oz. (avoir.) 



Sulphuric acid' 1% to 1^^ fl. oz. 



Water' 4^/2 fl. oz. 



Fumigate for one hour and then ventilate the room ten min- 

 utes before entering it. 



Sirrine's experiments with difi'erent amounts of the cyanide 

 lead him to the opinion that for g.meral use with well matured 

 nursery stock the amount should not be less than 1^ oz. per 100 

 cubic feet, which is the amount gi^en in the above formula.* 

 He finds, however, that stock, under some conditions, is injured 

 by even as small a quantity of the cyanide as this. Johnson 

 reports similar results and recommends for peach whip^, June 

 budded peach trees, bud sticks and in general all stock which 

 is not well matured, that the amount of potassium cyanide be 

 reduced to 18 grams (approximately f oz.) per 100 cubic feet.^ 

 When stock is to be fumigated which is not well matured it is 

 doubtless best tO' reduce the amount of the cyanide as Johnson 

 recommends, even if it is necessary to lengthen the time of 

 fumigation to get satisfactory results. Following Sirrine's ideas 

 in regard to the proportionate amounts of sulphuric acid and 

 water the formula for each 100 cubic feet of space would be as 

 stated below. 



°In this formula Mr. Sirrine recommGnds more sulphuric acid and water 

 to each ounce of potassium cyanide than is cilled for in some other for- 

 mulae which have been recommended by other entomologists. 



*Other entomologists recommend less amounts of the cyanide. Johnson's 

 formula calls for approximately ^a oz. per 100 cubic feet; Alwood uses 

 1 oz., Marlatt 1 oz. and Webster % oz. per 100 cubic feet for well matured 

 stock. 



'Johnson, W. G. 1. c. 



