INSECTICIDES AND FUNGICIDES. 



17 



Soluble sulfur is guaranteed as follows: 



Active ingredients, .... 

 Sodium polysulfide (Na^SO, ■ 

 Sodium thiosulfate, 

 Free sulfur, .... 



Inert ingredients, .... 



100.00 



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

 satisfactory. It is exceedingl}' dangerous as a foliage spray unless an excess 

 of lime is added. It has no marked superiorit}' over lime-sulfur prepara- 

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



Formulas for Application. 

 These various materials maj^ all of them be applied in such quantities 

 as to furnish approximately equivalent amounts of soluble sulfur. That 

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

 ratio between polj'sulfide 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-suHur concentrate (1-8 for dor- 

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

 as showing suggested formulas for application : — 



' 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.JlYS. 



Oil sprays owe their insecticidal value chiefly to their asphj'.xiating 

 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 actually 

 "hit." These oils will be considered under two divisions: (1) emulsions, 

 and (2) miscible oils. 



