292 INSECTICIDAL MATERIALS AND PRACTICES 



insecticide act of 1910, paris green must contain at least 50 per 

 cent of arsenious oxide, and must not contain arsenic in water- 

 soluble form equivalent to more than 3J per cent of arsenious 

 oxide. It is applied in either a wet or dry condition ; but in any 

 case, it must be much diluted. For making a dry mixture, plaster, 

 flour, air-slaked lime, road dust, or sifted wood ashes may be 

 used. The strength of the mixture depends upon the plants and 

 insects to which it is to be applied. The strongest dry mixture 

 now recommended is one part of poison to fifty of the diluent ; 

 but if the mixing is very thoroughly done, 1 part to 100, or even 

 200, is sufficient. 



Paris green is practically insoluble in water. When mixed with 

 water, the mixture must be kept in a constant state of agitation, 

 else the poison will settle, and the liquid from the bottom of the 

 cask will be so strong as to do serious damage, while that from 

 the top will be useless. For potatoes, apple-trees, and most 

 species of shade trees, 1 pound of poison to 200 or 250 gallons of 

 water is a good mixture. Paris green is very likely to burn the 

 foliage of stone fruits, especially peaches and Japanese plums, 

 and has been generally replaced by arsenate of lead for such 

 purposes. In all cases, the liquid should be applied with force, in 

 a very fine spray. At some seasons of the year foliage is more 

 liable to injury than at others. The addition of a little lime (twice 

 the bulk of lime as of paris green) to the mixture will tend to 

 prevent any caustic injury upon the foliage. 



Spraying with paris green or london purple does not endanger 

 stock pastured in the orchard. 



COMBINATIONS OF ARSENICALS AND FUNGICIDES. Arsenicals may 

 be used in connection with some fungicides, and both insects and 

 plant diseases in this manner may be combated at the same time. 

 The arsenicals may be added to bordeaux mixture in the same 

 proportion as if the bordeaux were plain water. Arsenate of lead 

 may be added to the lime-sulfur wash, but the addition of paris 

 green or arsenite of lime is liable to cause burning. 



The addition of lime to paris green and london purple mixtures 

 greatly lessens injury to foliage, and, as a consequence, they can 

 be applied several times stronger than ordinarily used, if they 

 are combined with the bordeaux mixture. The free lime in the 



