PLATE 8 



Sections of diseased sugar beets, showing the abrupt drying out between the dis- 

 eased and healthy tissue. The prominent "feeding surfaces" composed of recently 

 killed cells and the young hypha is clearly evident. 



A. — Cross section, showing complete girdling of the beet by cankers resulting from 

 separate points of infection. In such cases the continued penetration of the fungus 

 may completely sever the root at the line of greatest infection. 



B. — Longtitudinal section of diseased beet, showing various stages of decay and 

 the pulpy material partially filling the cankers. 



C. — Sugar-beet crown, showing the definite type of crownrot caused by the fungus 

 worked upward from a point of infection below the soil surface (PI. 6). A small region 

 of healthy tissue is shown to which a few sickly leaves were attached. 



D. — Section of beet stuface, showing progressive stages in the development of the 

 lesions resulting from natural infection. The earliest visible stage is shown to exhibit 

 a slight perforation of the outer surface at the center of the lesion. This small open- 

 ing, present in all lesions, gradually enlarges with age and finally results in the large 

 fissures (PI. 5). Various stages in the coalescence of lesions are especially evident. 



