REPORT OF SOCIETY 15 



"Nicofume", a 40 per cent solution of nicotine in the volatile form. Black 

 Leaf 40 can be combined with lime-sulphur, Bordeaux and arsenates of lead 

 and lime as a 3-in-l mixture, and is used at strengths varying from 1 to 800 to 

 1 to 1600 of water. 



Fungicides 



It is not surprising that plant growers of two or more generations ago had 

 difficulty in controlling plant diseases, since the nature of these maladies was 

 not understood. One has but to peruse some of the old works on the nature 

 and treatment of disease to find how crude were the conceptions of the early 

 plant growers and botanists, and how far the modern plant pathologist has 

 travelled during the last fifty or sixty years. 



Three outstanding factors contributed to the great development of our 

 knowledge of plant diseases and methods of control : 



1. — The epochal investigations of European botanists on the causal organisms 

 and their relation to such plant diseases as smut (1853), the potato-rot 

 disease (1861), and wheat rust (1865). 



2. — The rise of American investigators in the seventies and eighties, such as 

 Burrill, Farlow, Arthur, Bessey, Halstead, Earle and others whose 

 contributions added substantially to our knowledge of fungi and of fun- 

 gous and bacterial diseases. 



3. — The work of the U. S. Department of Agriculture and of the newly estab- 

 lished Agricultural Colleges and Experiment Stations which gave a 

 tremendous impetus to the study of plant diseases and control meas- 

 ures from 1885 onward to the present. 



It is true that sulphur and powdered lime were often dusted upon the plants 

 and gave some relief, but it is only since the discover^' of Bordeaux in 1883 that 

 the control of plant diseases has been carefully investigated. The plant pathol- 

 ogist has shown clearly that the fungicide should be applied just before the 

 rain, not after. In the case of apple scab, for example, the spores are carried 

 to the leaves during rains, and if the rainy spell lasts 48 hours infection will 

 take place. To protect the leaves, therefore, the spray must be apphed before 

 the rain. 



Again, the plant pathologist has shown clearly that a knowledge of the life 

 history of the fungus is essential if best results are to be secured in spraying 

 operations. 



