THE BACTERIAL BLIGHT 



167 



the Rhode Island Station, are shown in Plate XYI, 

 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 



a 



h 



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, Avliile 

 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 



