THE BACTERIAL BLIGHT 



167 



the Rhode Island Station, are shown in Plate XVI, 

 which is reproduced from a photograph taken August 

 20th. "The two rows in the center of the figure were 

 not treated with the mixture, consequently the leaves 

 all blighted and withered up soon after August 1st, leav- 

 ing only the bare, dead stems when the photograph was 

 taken ; while the leaves and vines in the rows on either 

 side, which had been sprayed with the Bordeaux mix- 

 ture, were fresh and green." 



The effect upon the tubers, of treatment with Bor- 

 deaux mixture, as it resulted in some experiments by 

 Professor Jones, of Vermont, is shown in Fig. 73. The 



b 



FIG. 73. 

 a, Yield of unsprayed plot; 6, of sprayed plot. 



treated vines yielded marketable tubers at the rate of 

 two hundred and ninety-one bushels per acre, while 

 those untreated yielded only at the rate of ninety-nine 

 and one-half bushels per acre. 



As a general rule, the first application of Bordeaux 

 mixture may be made when the vines are about one-third 

 grown, or earlier if signs of disease appear. Repeat the 

 application when it is washed off in about a fortnight 



