THE CONTROL OF INJURIOUS INSECTS 389 



finely powdered sulphur are added with constant stirring, also sufficient 

 water to prevent burning. Then add water to make 40 gal. This 

 liquid is a mixture of lime and sulphur, for little combination takes 

 place, and is a good fungicide against brown rot of stone fruits. It is 

 not used to any great extent by fruit growers. 



Sulphur and Lime. — Flowers of sulphur and hydrated lime in equal 

 parts, when blown upon citrous trees, keep in control red spiders and 

 mites. 



Recent experiments in Nova Scotia show that arsenate of lime is 

 preferable to arsenate of lead as a poison with lime-sulphur solutions. 

 When standard arsenate of lead is added to lime-sulphur a double 

 decomposition occurs with the formation of lead sulphide and a crude 

 arsenate of lime, 5 per cent, of which is soluble. 



When the soluble sodium sulphides, such as "soluble sulphur," 

 "sulfocide," "spra sulphide," etc., are used in combination with arsen- 

 icals of copper, lead and zinc soluble arsenical salts of sodium are formed 

 v/hich are unsafe as apple sprays. However, when used with arsenate 

 of hme and water-slaked lime (3 lb. soluble sulphur, i}^ lb. arsenate 

 of lime and 5 to 10 lb. water-slaked lime) no injury results to apple 

 foliage. 



In Nova Scotia it has been found that when the common poisons 

 are added to Bordeaux mixture their killing power is usually decreased 

 by about 50 per cent. Sodium arsenate, however, retains its power 

 after its addition to Bordeaux if prepared as follows: 



Dissolve I lb. sodium arsenate in water and with this solution slake 

 5 lb. of fresh stone lime and make up to 20 gal. Dissolve 4 lb. blue- 

 stone in another 20 gal. of water and pour the two together. 



Sodium sulphide, on the other hand, increases the kilUng value of 

 poisons. 



With the advent of high power sprayers complaints have come in 

 regarding injury to and drop of the leaves and fruit of trees sprayed 

 with the summer strength of lime-sulphur, especially with the later 

 sprayings. This result is due to the destructive action of the lime- 

 sulphur on the contents of the leaf-cells. Experiments showed that 

 when the upper surface of the leaves only was sprayed no drop of 

 leaf or fruit ensued, but when the spray was applied to the under surface 

 much drop followed. This result does not follow the application of 

 sodium sulphide or Bordeaux. 



