New York Agricultural Experiment Station. 93 



However, the results appeared encouraging and from 

 theoretical considerations it seemed reasonable to expect that 

 the leaf-pulling treatment might be successful. Moreover, it was, 

 at that time, the only lirfe of treatment whicb had been suggested. 



Accordingly, the writers set out to test it thoroughly and deter- 

 mine definitely whether it is a preventive of the disease, and also 

 whether it is a profitable operation under commercial conditions. 



method of treatment described. 



In general, the method of treatment is as follows: 

 The plants are carefully watched for the first appearance of 

 the disease, which usually occurs about August i. Thereafter, 

 the field is gone over, row by row, once a week, and every leaf 

 showing signs of the disease is broken ofif and carried out of the 

 field. Whenever there is found a plant in which the disease has 

 already gotten into the stem, as shown by the presence of black 

 streaks in the basal portion of the leaf stalks, such plant is 

 promptly' removed from; the field. It has been the practice of 

 the writers to carry a large market basket intO' which the diseased 

 leaves are placed as fast as gathered. When the basket is filled 

 it is carried to the margin of the field and emptied. 



It may be stated here that in the experiments described in this 

 bulletin the work of removing the diseased' leaves was not en- 

 trusted to laborers. Most of it was done by the writers them- 

 selves and the remainder by Messrs. F. M. Rolfs and H. J. 

 Eustace, assistants in the Botanical Department, and L. A. 

 Rogers and J. F. Nicholson, assistants in the Bacteriological 

 Department. The writers wish to thank these gentlemen for their 

 efficient assistance. 



THEORY OF THE TREATMENT. 



In many cases the disease starts at the margin of the leaf 

 (see Plate I); sometimes, also, in leaf wounds made by insects, 

 and then passes downward along the fibro-vascular bundles 

 (veins) into the stem of the plant. 



As a rule, several days are required for the disease to reach 

 the stem. Once the disease is within the stem it is beyond con- 



