PROCEEDINGS, 1918 69 



SOME MISCELLANEOUS OBSERVATIONS ON THE 

 ORIGIN AND PRESENT USE OF SOME IN- 

 SECTICIDES AND FUNGICIDES. 



By G. E. Sanders and A. Kelsall. 



Introduction. 



That "necessity is the mother of invention," is a state- 

 ment well supported by the rise into prominence of all the best 

 known insecticides and fungicides. The insecticides and 

 fungicides that are very widely used and known are in reality 

 only four, namely, Paris green, lead arsenate, Bordeaux mix- 

 ture, and lime-sulphur. Of these each and every one was only 

 developed for its present purpose in the face of the greatest 

 need. Paris green to combat the potato beetle, lead arsenate 

 to check the gypsy moth, Bordeaux mixture to control the 

 downy mildew on the grape in France, and lime-sulphur to 

 combat the San Jose Scale. In each case the pest concerned, 

 threatened the extermination of its host, and the remedy was 

 found from pure necessity. 



Paris Green. 



The history of Paris green is intimately associated with 

 the history of the potato beetle. The familiar potato "bug" 

 was originally a native of the Rocky Mountains in the U. S. 

 region, and when potato culture had extended so far West that 

 the plant was grown in territory occupied by the beetle, the 

 beetle left the plants on which it had been feeding and attacked 

 the potato vines. This was about the year 1850. Then com- 

 menced the march east and north, and every successive year 

 saw more and more territory invaded by this unwelcome tra- 

 veller. By 1870 the pest had reached the Atlantic coast, and 

 to the north had entered Ontario. Every one acquainted with 

 the potato beetle can well realize the trail of destruction fol- 

 lowing in its wake. It was freely predicted that the potato 

 was doomed as a field crop, and the entire potato industry seem- 

 ed seriously threatened. 



At this time Paris green was quite a popular shutter paint. 

 Just exactly who first tried it on potato foliage is not known, 

 probably it originated with several persons. The practice 

 started in the Western States sometime shortly after 1860, and 

 by 1870 the sifting of Paris green powder on to potato foliage 



