CONTROL OP' BIvACKLE;G DISEASE; OF THE; POTATO. 21/ 



Mountain 91-2 acres, Irish Cobblers 4 acres, Early Rose, 2 

 acres, Beauty of Hebron i 1-2 acres, Twentieth Century i acre. 



Since the Irish Cobbler was the only variety treated where 

 a check plot was saved this is the only case in this experiment 

 where accurate comparison could be made between treated and 

 untreated seed from the same source. However, since the dis- 

 ease did develop on the other portions of the field with other 

 varieties which had been treated it is of interest to note these 

 facts as bearing upon the effectiveness of the gas method of 

 disinfection. While the results with some of the varieties in 

 this experiment were not equal to the expectations of the writer, 

 Mr. Edblad expressed himself as entirely satisfied with the 

 results from a commercial standpoint and stated that he felt 

 that he had profited sufficiently to more than pay for the ex- 

 pense and trouble involved in treating his seed. 



The field was visited on July 7 but on account of not being 

 able to definitely locate the boundaries of the different plots no 

 accurate record was made at that time. On July 20 the field 

 was examined in the company of Mr. Edblad by carefully going 

 over representative plots of each different variety of one-fourth 

 to one-half acre in size. Calculated in number of diseased 

 plants per acre there was : 



Seed tubers untreated, Irish Cobbler. 



Diseased plants per acre 96 



Seed tubers treated (formaldehyde gas), Irish Cobbler. 

 Diseased plants per acre * o 



Seed tubers treated (formaldehyde gas), Green Mountain. 

 Disea5ed plants per acre o 



Seed tubers treated (formaldehyde gas), Early Rose. 

 Diseased plants per acre 18 



Seed tubers treated (formaldehyde gas), Twentieth Century. 

 Diseased plants per acre 40 



No record was made as to the amount of blackleg on the 

 one and one-half acres of Beauty of Hebron. Mr. Edblad 



* The record was taken for the treated and untreated Irish Cobblers 

 on adjoining plots July 20. At the time of the early visit (July 7) a few 

 diseased hills were seen on another part of the field where treated Irish 

 Cobblers had been used, so the effectiveness of the treatment in this 

 case was doubtless not quite so great as the figures would indicate. 



