11 



pie scab disease and the almost universal occurrence of th^^ 

 apple, cultivated or escaped, makes the application of 

 methods based on either of the first two principles quite out- 

 side consideration. That method (spraying) most generally 

 employed to combat this disease is based entirely upon the 

 principle of protection of the host plant, fruit and leaf from 

 attacks of the pathogenic fungus. IMethods of immuniza- 

 tion, such as selection and propogatiou of resistant varie- 

 t"es, etc., are of little value to this generation of apple grow- 

 ers who must look to the varieties already producing, for 

 their returns and remuneration. To the question of spray- 

 ing then we address our attention. 



The History of Spraying for the Control of Apple Scab 

 in this country dates approximately from 1885 when Saun- 

 ders in Canada and Goff in New York laid out and conduct- 

 ed apple spraying experiments with a form of lime-sulfur. 

 (Lodeman, The Spraying of Plants 1896 p. 88.) The then re- 

 cently discovered bordeaux mixture used so effectively by 

 French vineyardists against the grape mildew was first sug- 

 gested for apple scab by Lamson Scribner, Assistant Botan- 

 ist of the U. S. Department of Agriculture in his annual re- 

 port for 1885. It was soon generally recommended and em- 

 ployed and quickly proved its efficiency against the scab 

 fungus. Its use became general among those growers who 

 sprayed, not only in New York but throughout the other 

 apple growing sections of the United States. Two factors 

 of fundamental importance, however, tended with increas- 

 ing force to dissatisfaction with bordeaux as a fungicide for 

 apple spraying. From the first it was observed that russet- 

 ting of fruit and yellowing and falling of leaves frequently 

 followed spraying with bordeaux mixture. Especially was 

 this the case in wet seasons in which spraying was most 

 necessary. In the second place commercially prepared bor- 

 deaux was generally held to be inferior in efficiency to the 

 home made mixture and more expensive. I hold it to be a 

 fundamental principle that a fungicide to be universally 

 and continuously acceptable must be of a nature to be made 



