Mar. 17, 1919 Fusarium-B light of Potatoes under Irrigation 293 



per cent) are placed in the table according to the place they occupy in 

 Table I, C, and it is regarded as of no significance that they fall where 

 they do. 



EARLY OHIO (TABLE I, E-F) 



The Early Ohio seed obtained from the Red River Valley consisted of 

 two lots. These lots were grown separately, but their performances were 

 so nearly alike that they have been combined and presented in Table I, 

 E, as one lot. 



This table shows plants falling in the DHDH, DD,AA, and 00 squares, 

 a tendency not noted in the previous tables. In the case of the plants 

 falling in DHDH, it would appear that some special weakness had devel- 

 oped in the 22 plants grown from these 1 1 tubers which placed them there. 

 Inherent weakness, then, can not be predetermined by mere examination 

 of the tubers, because Table I, F, which represents the location of the 

 tubers showing vascular discoloration (9.07 — per cent), placed according 

 to their location in Tables I, E, has none represented in DHDH. These 

 plants outgrew their earliest diseased condition, and finished the season 

 in apparent healthy condition. Table I, E, does not indicate, however, 

 any strong vigor on the part of this lot. 



Table I, F, represents the place the 35 tubers of Table I, E, which 

 showed vascular discoloration fell, placing them according to their loca- 

 tion in Table I, E. 



RURAL NEW YORKER (TABLE I, G.) 



One lot of seed of the Rural New Yorker variety was obtained from 

 the Carbondale District of Colorado. It consisted of 320 tubers, free 

 from vascular discoloration, and was regarded as stock of superior quality, 

 selling at an advanced price. Table I, G, illustrates the almost complete 

 failure of this seed through seed-piece infection and rot in the Greeley 

 District. 



In this table, where so much disease is represented, the conspicuous 

 absence of plants falling in the HD columns (i in the even row), and 

 in the DD square, is significant. Root infection did not occur; no vascular 

 discoloration was present in the seed. The great preponderance of 

 plants in the 00 square and the O columns, shows clearly that a most 

 serious inherent weakness is present in the seed to withstand infection 

 from the soil. The number of plants that did not eventually become 

 healthy, having previously grown and been diseased, are very few. 

 There is a strong tendency to die or survive (H or DH), for the plants that 

 are H or DH were vigorous at the end of the season. The others either 

 failed, as in O, or gave evidence of a gradually decUning health, as in 

 D and A. The lack of plants in the HD columns (i in the even row) is 

 further evidence that a healthy plant maintains its position. 



