176 



Journal of Agricultural Research 



Vol. IV, No. 2 



fungus mycelium may remain dormant for a longer period of time in a 

 sugar-beet root or "mother beet" stalk. The writers have found no 

 evidence of a perfect stage of the organism. 



The leaves for the outdoor-exposure experiments were buried in such a 

 manner that examination was rendered convenient and accurate. The 

 following method was suggested by Mr. W. A. Orton, Pathologist in 

 Charge of Cotton- and Truck-Disease and Sugar-Plant Investigations, 

 Bureau of Plant Industry. The soil was removed to the depth required 

 and a piece of 2 -inch mesh wire was placed on the exposed ground surface. 

 The layer of leaves was then packed over this, another layer of wire added, 

 and then soil to the depth desired. In examining the leaves at any time 

 the layer of wire served to show the position of the leaves, and definite 

 spots could be taken for cultural material. The effect of outdoor 

 winter conditions on the viability of Phoma betae in infected beet tops is 

 given in Table II. 



Table II. 



-Effect of different methods of overwintering on the viability of Phoma betae 

 in infected beet leaves 



Method of treatment of infected leaves. 



Buried in soil in box 



Do 



Do 



Buried I inch in ground 



Do 



Do 



Do 



Buried 2 inches in ground 



Do 



Do 



Buried 3 inches in ground 



Do ■ 



Do 



Buried 4 inches in ground 



Do 



Do 



Buried 5 inches in ground 



Do 



Do 



Buried 6 inches in ground 



Do 



Do 



Buried 7 inches in ground 



Do 



Do 



Do 



Buried 8 inches in ground 



Do 



Do 



Do 



Interior of "hayed" pile of beet tops. 



Do 



Do 



Do 



Left in field on surface of ground 



a String-bean agar was used for all cultures. 



b The number of spots used for each cultiu-al plate varied from i to 4 or 5. 



