18 PROTECTION OF PLANTS, 1920-21 



In this very incomplete review an attempt has been made to make clear 

 the chief outstanding events in the story of spraying mixtures. These are : — ■ 



1. — -The use of Paris Green against biting insects, between 1860-1870. 



2. — The introdubtion of Bordeaux mixture as a fungicide, about 1885. 



3. — -The introduction of lime-sulphur, first as a contact insecticide and later 

 as a fungicide in 1906. 



4. — The use of lead arsenate and calcium arsenate as insecticides against biting 

 insects. 



5. — The u^e of Kerosene emulsion and tobacco extracts as contact insecticides. 



6. — The practicability of combining the more important insecticides and fung- 

 icides in one mixture for spraying purposes, thus saving much time in 

 spraying operations. 



7. — The manufacture of spray materials in finely powdered form and the 

 introduction of dufet-spraying, making for much saving of time. 



8.— A better knowledge of the chemical reactions that occur when different 

 spraying materials are brought together, and of the physiological action 

 of these mixtures on the leaves of plants. 



9. — A better knowledge of the life history of insects and fungi, so that the spray 

 applications are made at times when they will be most effective. In 

 other words, the spray calendars are now based on the stage of dev- 

 elopment of planit, insect and fungus, and not as formerly on the 

 almanac. 



10. — ^Glosaly connected with developments in spraying is the development of 

 spraying outfits, which this paper does not attempt to discufes. 



In conclusion, it is a pleasure to note the part taken by Canada in the story 

 of sprajang mixtures, although she has in most cases followed the lead of the 

 United States and Europe. 



Mention has already been made of the splendid investigations carried on in 

 Nova Scotia by Sanders, Kelsall and Brittain in connection with lime-sulphur 

 injury, and with the making of dust mixtures, but credit should be given to 

 Saunders and Reed, of T-ondon, Ontario, for their early experiments (1871) with 

 various chemicals for the control of the potato beetle, to Cline, of Winona, and 

 McMichael, of Waterford, for their experiments with orchard insecticides and 

 fungicides from 1883 to 1887, to Prof. Craig, of the Dominion Experimental 

 Farm, for experiments on the control of apple scab and other diseases with Bor- 

 deaux and other fungicides (1890-1894), to Dr. Fletcher for his experiments 

 on the control of many injurious insects, and to the Ontario Agricultural College 

 for experiments with lime-sulphur and other substances against the San Jose 

 scale. 



