12 PROTECTION OF PLANTS, 1920-21 



PRESIDENT'S ADDRESS 

 THE STORY OF SPRAYING MIXTURES 



W. Lochhead, Professor of Entomology and Zoology, Macdonald College, P. Q . 



Prior to 1860 the methods of protection of plants from insects and fungous 

 diseases were extremely crude and primitive. Practically nothing was known 

 about the nature of fungous diseases, and although insects had been studied for 

 many years, no serious attempt had been made to control the injurious forms 

 with chemicals. The best insecticides in use were various forms of soap, tobacco, 

 quassia chips, carbolic acid and hellebore. 



As we all know, spraying mixtures are of two kinds : — Insecticides and 

 Fungicides, but some mixtures, like lime-sulphur and soluble sulphur, belong to 

 both groups. 



Insecticides 



In the development of insecticides, as of other phases of economic entomol- 

 og}^, the United States has taken the lead over all other nations. Two out- 

 standing factors contributed to this wonderful progress : — 1. The losses which 

 certain portions of the country suffered at various times from (a) the potato 

 beetle ; (b) the Rocky Mountain locust ; (c) the cotton caterpillar ; (d) the 

 San Jose scale ; (e) the cotton-boll-weevil ; (f) the Gypsy and Brown Tail moths, 

 brought public opinion to bear strongly upon Congress so that measures were 

 taken to discover methods of control ; 2. The establishment of State Agricul- 

 tural Colleges and Experiment Stations which made it possible to train men 

 for the investigation of such problems. 



It is interesting to note that, in the matter of insecticides, methods of fumig- 

 gation with hydrocyanic acid gas, and spraying with lime-sulphur and resiny 

 washes were developed first on the Pacific Coast, while arsenical sprays and 

 mineral oil preparations were developed in the East. 



Paris Green. — Paris Green was the first insecticide of merit to be employed 

 against biting insects. During the sixties, it came into use against the Colorado 

 beetle, in the seventies it was successfully used against the cotton caterpillar 

 and against canker-worms and the codling moth in orchards, and in the eighties 

 against the plum curculio and other pests. By 1890 Paris Green had become 

 the standard insecticide against biting insects. However, this and other ars- 

 enite compounds, like London Purple and the Kedzie mixture made from white 



