POTATO DISEASES IN I907. 315 



which he had placed his potatoes to be treated. As a result, sev- 

 eral barrels of tubers were severely injured, the eyes of those 

 nearest the generator being entirely killed. 



To test the matter in our own disinfecting chamber a few 

 tubers were placed in a basket and suspended 6 inches above 

 and directly over the generator just before it was charged and 

 were thus exposed during the period of disinfection. All the 

 eyes in these tubers were killed. After a few days the injury 

 was very apparent. The tissues around the eyes were browned 

 and depressed, forming well-marked pits. Cutting into the 

 tubers showed that the injury extended down into the flesh 

 one-fourth of an inch or more. See Figure 49 p. 326. ■ 



Samples of tubers exposed during the same period were 

 removed from bins in various parts of the room and taken to 

 the laboratory for examination. None of the eyes were affected 

 and germination was normal. 



With the exception of the first 2 or 3 acres planted, the stand 

 on the 20 acres where the seed was treated with gas was exceed- 

 ingly even and showed very few missing hills. The somewhat 

 uneven stand on the part of the field mentioned was, in the 

 writer's opinion, due to the poorer grade of seed used and to 

 the cold, wet weather which prevailed when the planting was 

 begun, rather than to any effect of seed treatment. The fact 

 that a measured acre of this portion of the field produced a 

 total yield of 168 barrels (462 bushels) indicates that whatever 

 was the cause of the slight uneven germination, the resulting 

 yield was unusually satisfactory on this area. Careful records 

 on acre plots in various parts of the 20-acre field, covering over 

 a third of its area, showed yields varying from 125 to 168 bar- 

 rels, one other acre in addition to the one already mentioned 

 reaching the latter figure. 



ADDITIONAL DIRECTIONS FOR FORMALDEHYDE GAS DISINFECTION. 



Recent experience suggests the folldwing modifications and 

 additions to the directions for formaldehyde gas disinfection 

 as given in Bulletin No. 141. 



The generator should be placed in an open space in the 

 •center of the disinfecting chamber, the bins or crates so 

 arranged that the gas can circulate on all sides of them and 



