New York Agricultural Experiment Station. 343 



commercial insecticides. 



Some commercial substitutes for the standard poisons are : Para- 

 grene, Green Arsenoid, Green Arsenite, Pink Arsenoid, Laurel Green, 

 Arsenate of Lead and Disparene. 



These are sometimes used in preference to the poisons previously 

 mentioned. But before adopting any one of them for exclusive use, 

 it is advised that a competent chemist be consulted. 



Among the proprietary contact poisons are Slug Shot, Derror's 

 Fluid, etc. These are comparatively costly. They possess no ad- 

 vantage over standard remedies. 



WHAT IS THE MOST DESIRABLE SPRAY AND HOW 



OBTAINED? 



In applying bordeaux mixture or other fungicide to any foliage 

 it is evident that perfect work is done when the spray covers the 

 leaf surface most completely and permanently. The same is true 

 of spraying with arsenical insecticides or other insecticides which are 

 applied to the leaf for the purpose of killing insects by poisoning 

 their food. Experience shows that with liquid preparations this may 

 be best accomplished when the liquid is broken into so fine a spray 

 that it will rest upon the leaf in mist-like particles and dry in that 

 position. In practical operations, before every leaf becomes covered 

 in this way the liquid will often drip from some of the leaves. Never- 

 theless, the aim should be to cover eve'ry leaf in the manner described 

 and in so doing to avoid as much as possible making any of the 

 foliage so wet that it will drip. Any portion of the leaf surface 

 which is not covered witJi the spray mixture evidently remains un- 

 protected from the attacks of the fungi. Not only may a much better 

 spray be applied with a perfect mist than with a coarse spray but it 

 may also be applied with less expense of time and of material. 



It is beyond question that a pressure of from 100 to 120 pounds 

 gives a finer mist than can be obtained with the same apparatus under 



