INSECTICIDES AND FUNGICIDES. 



17 



Soluble sulfur is guaranteed as follows : — 



Active ingredients, ..... 

 Sodium polysulfide (Na2S4), . 

 Sodium thiosulfate, .... 

 Free sulfur, ..... 



Inert ingredients, ..... 



100.00 



Soluble sulfur is used considerably as a dormant spray, and is fairly 

 satisfactory. It is exceedingly dangerous as a foliage spray unless an excess 

 of lime is added. It has no marked superiority over lime-sulfur prepara- 

 tions, and has not supplanted them to any great degree. 



Formvlas foi' Applicaiion. 

 These various materials may all of them be applied in such cjuantities 

 as to furnish approximately equivalent amounts of soluble sulfur. That 

 this basis is not entirely sound is shown by the fact of difference in the 

 ratio between polysulfide sulfur and thiosulfate sulfur. This difference 

 should, of course, be considered when computing amounts of spray 

 materials needed. On the basis of amounts of soluble sulfur equal to the 

 standard application of 33° Baume lime-sulfur concentrate (1-8 for dor- 

 mant spray and 1-40 for summer spray), the following table is presented 

 as sho^^"ing suggested formulas for application : — 



1 These amounts are greater than are recommended by the manufacturers. 



- Soluble sulfur should never be used as a summer spray, save with a great excess of lime. 



3. Oil Spr.ws. 



Oil sprays owe their insecticidal value chiefly to their asphyxiating 

 effect. To a certain degree some of them may also have corrosive effect. 

 Oil sprays likewise have a peculiar creeping power which enables the 

 operator to cover the tree area even under unfavorable conditions. With 

 most other contact insecticides, an insect to be killed must be actualh' 

 "hit."' These oils will be considered under two divisions: (1) emul.'^ions, 

 and (2) miscible oils. 



