220 Maine; agricuIvTurai, expe;rimi;nt station. 1911. 



During this period blackleg has been observed but once and 

 then only three or four plants were seen on a 20-acre field — 

 a record, so far as observed, not equalled by any other field 

 in the immediate neighborhood where untreated seed tubers 

 were used. 



Selection versus Disinfection: An analysis of the data fur- 

 nished by these experiments does not lead one to any very defi- 

 nite conclusion as to the relative value of selection of sound, 

 perfect seed potatoes for planting as compared with disinfection 

 with formaldehyde alone. As has been pointed out above both 

 apparently are necessary. In the Porter experiment, where the 

 seed carried only a small amount of disease in the beginning, 

 disinfection alone failed to eliminate all of it while selection did. 

 On the other hand in the Hussey experiment with Green Moun- 

 tains where the seed carried considerable disease it was abso- 

 lutely eliminated by treating with formaldehyde solution alone. 

 However, the writer believes that careful selection of seed 

 tubers and rejecting for planting all that are in any way cracked, 

 bruised, discolored or decayed is absolutely essential and no 

 amount of disinfection with present known methods can be 

 relied upon to entirely take the place of it. On the other hand 

 the formaldehyde treatment appears to be equally essential and 

 must be practiced to supplement selection of seed. 



Gas versus formaldehyde solution: In no case except the 

 Blake experiment were adjoining plots planted to compare the 

 relative effectiveness of formaldehyde gas and solution. Here 

 practically no disease developed on either piece and the check 

 did not admit of accurate comparison. The writer was present 

 when Mr. Blake's crew were treating and cutting seed and 

 knows that it was quite carefully selected. Doubtless much of 

 the freedom from disease in this instance was the result of seed 

 selection. In the Cleveland Company and Edblad experiments, 

 the only ones in which gas alone was used, the results are not 

 so uniformly effective as in the case of the experiments where 

 the seed tubers were soaked in formaldehyde solution. In each 

 case where the best results were obtained with formaldehyde 

 solution the owner of the potatoes was able to either cut the seed 

 himself or be present and personally superintend the work at 

 all times. This was not the case where the gas alone was used 

 and the average man employed to cut seed cannot be depended 



