15 



9. Lime added to a mixture of white arsenic in water 

 will greatly increase the injury that this poison w^ould other- 

 wise do to foliage. If the arsenic is all in solution, the lime 

 will then lessen the injury, as in the case of London purple 

 and Paris green. 



10. London purple (Paris green and white arsenic have 

 not yet been tried) can be used, at least eight or ten times 

 as strong, without injury to foliage if applied in common 

 Bordeaux mixture instead of water. 



11. The arsenites cannot by any ordinary method be suc- 

 cessfully mixed in a kerosene emulsion. 



12. London purple in sulphate of copper solution does 

 vastly more harm than when applied in water only. 



Mr. C. W. AVood worth, the entomologist of the Arkansas 

 Experiment Station, in Bulletin No. 14, September, 1890, 

 publishes the following conclusions relative to the effects of 

 arsenites upon plants : — 



1. The injury from white arsenic is seen comparatively 

 very soon after it is applied. London pur[)le is almost as 

 active. 

 • 2. Paris green does its injury much more slowly. 



3. Young leaves are affected much more quickly than 

 are the old ones. 



4. Applications to the lower side of a leaf produce injury 

 more quickly than if the poison is applied above. 



5. Except in the case of young leaves, it seems to be the 

 rule that where the greatest injury is produced, a greater 

 proportion is early apparent. 



Danger in Using Insecticides. 



" It has been shown, both by experiment and practice, that 

 there is no danger to be apprehended from eating fruit sprayed 

 either with the compounds of arsenic, or with Bordeaux 

 mixture. It is just as well to keep stock out of orchards for 

 a few days after spraying the trees ; but really there seems 

 to be small danger from allowing stock the run of an orchard 

 at all times. If the spray has been properly applied very 

 little of it drops from the leaves afterwards." (Circular No. 

 3, Kentucky Agricultural Experiment Station, Garman.) 



" There is no danger whatever if ordinary care be used. 



