CHAPTER IX 

 INSECTICIDES AND FUNGICIDES: FUMIGATION 



COMBINATIONS OF SPRAY MATERIALS 



The greater part of the cost of spraying comes from the time and 

 wages of the workers, the materials used being rather inexpensive in 

 comparison. Wherever it is possible therefore, to make two or three 

 applications at once by using combined sprays, the cost is much reduced. 



Frequently there are cases where the application of a stomach poison 

 for chewing insects and of a contact insecticide for sucking forms, can 

 be made at about the same time. Treatment for fungous diseases may 

 also be desirable, and a satisfactory mixed spray for all three purposes 

 can often be given. Certain precautions must be taken in mixing sprays, 

 however, as in some instances the materials of two or more sprays, when 

 combined, will undergo changes, producing substances injurious to the 

 plant or affecting the value of the spray for the purpose for which it was 

 intended. 



No spray material containing soap should be combined with one con- 

 taining lime, as when these materials are brought together, a calcareous 

 and insoluble soap is formed. Thus, when nicotine sulfate is used with 

 lime-sulfur or Bordeaux mixture, the soap usually added to the former 

 must never be put in. Arsenate of lead and compoands containing 

 sodium or potassium sulfid, when mixed, produce sodium or potassium 

 arsenate which is very soluble and will injure foliage, so this combination 

 should also be avoided. 



Bordeaux mixture, a fungicide, combines well with most of the insec- 

 ticides except those containing soap, but as it contains lime, an insec- 

 ticide with soap is not safe for this combination. In most cases the 

 Bordeaux mixture ready for spraying can be regarded as an equivalent 

 amount of water, to which to add the insecticide. For example, in 

 combining Bordeaux and arsenate of lead, simply add 3 lb. of the paste 

 to 50 gal. of the Bordeaux. 



Bordeaux mixture will safely combine with any of the arsenical 

 poisons given in this book, and also with nicotine sulfate if the soap 

 be omitted. Lime-sulfur at summer strength may be used with arsenate 

 of lead or nicotine sulfate, leaving out the soap, though in the former 

 case a decomposition is liable to take place which reduces the value 

 of the material. Lime-sulfur at winter strength when added to the 



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