50 



Journal of Agricultural Research voi. xxii. No. i 



beets in the control row healed normally. Infection occurred on but 

 one beet in rows 3 and 4. The other beets in these two rows healed as 

 perfectly as in row 5. The results of inoculation with the sugar-beet 

 strain of the fungus in rows i and 2 are given in Table I. The types 

 of lesions produced as a result of atrificial inoculation are shown in 

 Plate 9, A. D. 



Table I. — Number of lesions on sugar beets inoculated with the sterile stage of Corticium 



vagum 



Instructions for the inoculating of sugar beets with the beet fungus 

 without puncture or incisions were not followed. As a result the question 

 as to the ability of Corticium vagum to attack the sugar beet independ- 

 ently of other agents remains unsettled. It is quite conceivable that 

 sugar-beet root aphis {Pemphigus betae Sloane) and other insects so 

 prevalent in the soil may serve an important function in the initial en- 

 trance of the fungus. Having once gained access to the lower tissue, 

 however, it appears evident from the results that this particular "strain" 

 of C. vagum is capable of producing the type of canker and dryrot with 

 which it is so constantly associated in the field. 



The peculiar method of decay, together with the sharp line of demarca- 

 tion between the diseased and the normal tissue (PI. 8, A-C; 9, C-F), pro- 

 vide the most distinctive characteristics of the disease. A dark brown, 

 watery layer invariably separates the dry, decayed mass occupying the 

 cavity of the canker from the normal host tissue beneath. This layer 



