224 MAINE) AGRICUIvTURAI, EXP^RIME^NT - STATION, I9II. 



acre showed blackleg. On the adjoining portion where the 

 tubers were used which remained out in the barrels after being 

 cut about 20 per cent of the hills had either failed to germinate 

 or were attacked by blackleg. Somewhat less than one-third of 

 an acre was examined and the diseased plants counted, giving 

 325 per acre where the "heated" seed was used. 



It was evident that the seed tubers in this instance were quite 

 free from disease. To the casual observer there appeared to be 

 an absolutely perfect stand over the entire field except where 

 the seed had been injured by standing in the barrels. The 

 small amount of blackleg that the potatoes originally carried was 

 largely increased as the result of the germs of the disease multi- 

 plying in and on the infected pieces and then being communi- 

 cated to the healthy seed pieces in handling and planting. 



No doubt quite a proportion of the failures to germinate 

 were due to the same cause. However, other bacteria and fungi 

 are, as a rule, associated with germination failures and seed 

 potato decay after planting. It is well known that poor stands 

 will result where cut seed tubers are allowed to stand in bar- 

 rels or in piles for any length of time without proper attention, 

 even where blackleg is entirely absent. 



Treating Stto Potatoes with Formaldehyde Solution 

 After Cutting 



It is the universal practice to recommend that potatoes be 

 soaked in formaldehyde solution before cutting when treating 

 for scab. The writer has followed this procedure in advising 

 treatment for blackleg. It is obvious that soaking after the 

 seed is cut possesses decided advantages, provided the seed 

 pieces are not injured thereby. If the latter process is followed 

 more thorough disinfection would result and much, if not all, 

 of the danger of chance contamination of healthy seed pieces 

 would be avoided. Realizing the advantages of this method Mr. 

 Donaldson tried it experimentally with very successful results. 

 Not only were the germinating qualities of the tubers not in- 

 jured but a more even stand was secured and, as will be seen 

 in the next section, they were stronger and more vigorous dur- 

 ing the early part of the season. 



It is not safe to make general recommendations on the 

 strength of this single trial alone but those who are treating 



