BEPOBT OF THE SOCIETY 19 



in 1795; Pflanzen-Paihologie und Therapie by Freiherr von Werneck in 1807; 

 and a very comprehensive work by Count Re of Italy in the same year. 

 Unfortunately they had no clear understanding of parasitism and there- 

 fore their work was of little importance. In fact the understanding of 

 parasitism came rather slowly. During the early pai?t of the 19th century it 

 was first believed that the existence of parasitic fungi was conditioned by the 

 host, that they were not reprodu(^ed by spores, but developed from fermenting 

 sap of the host or from abnormal tissues. Finally when it became evident 

 that they came from spores, it was believed that they were the products of di- 

 sease, that their forms depended on the species of the host; or condition of host 

 at time of infection. Efforts to control wheat rust by the enactment of laws 

 were made in France as early as 1660 and in America in 1755. It is interesting 

 to note that these same methods are being tried at this time. Treatments of 

 various kinds have bfeen used 150 years or more but with little success imtil the 

 worker recognized the true causes of diseases. Two outstanding events did 

 much to stimulate modern plant pathology. The first was the series of out- 

 breaks of the late blight of the potato in Eu^-op'e and America, especially the 

 outbreak in Ireland which resulted in the famine of 1845. This demonstrated 

 the importance of plants diseases as economic factors. The second was the dis- 

 covery of Bordeaux Mixture in Fra,"nce in 1882 which demonstrated the possibi- 

 lities of controlling plant diseases. 



Having recognized and gained some knowledge of the causes of plant disea- 

 ses; having learned something about the enormous losses in both wealth and 

 human life due to them; having learned that it is possible to prevent and control 

 them; the rise of plant pathology into a place of prominence and importance 

 was inevitable. This rapid rise of plant pathology has made the botanical 

 sciences more complex and more dependent on other sciences. The increasing 

 population and the corresponding increase in the demand for agricultural pro- 

 ducts has forced the recognition of the importance of plant pathology in relation 

 to crop production and to human welfare in general and has materially increased 

 our responsibility to the public. It is estimated that the population of the 

 Unites States will double within the next 100 years and that we will then have 

 reached the limit that can be maintained by our own farm products. I suspect 

 the same is true for Canada. Will the improvement in methods of controlling 

 plant diseases reduce the losses, increase crop production and thu^ make it 

 possible for North America to support a larger population than now estimated ? 



The very rapid development of plant pathology within the past few years 

 has not been without its faults and dangers. Although the founders of plant 

 pathology were well trained in botany, the same cannot be said of all the mem- 



