Diseases of the Sugar Beet. 



347 



Experiment Station, the fungus was described in considerable 



detail. 



During the past two years I have continued studies upon cer- 

 tain damping off fungi, and this sterile fungus has often been 

 found as the cause of damping off in seedling lettuce, beans, and 

 cucumbers, and occasionally in manj^ other seedlings. That the 

 fungus referred to is the cause of these troubles has been proved 

 in the case of the lettuce and radishes by inoculation with pure 

 culture. Seedlings affected by this fungus show the usual char- 



53. — Germinating cells of the Root-rot fungus . 



acteristics of damping off. The plants first show signs of weak- 

 ness near the surface of the ground, the water-soaked tissues of 

 this region are soon unable to support the plant, and it may fall 

 prostrate on the surface of the ground, the fungus soon invading 

 all parts. Among lettuce seedlings, especially, this fungus 

 spreads rapidly from plant to plant ; and a box of seedlings may 

 have the appearance of being wilted down, as in figure 54. 

 Damping off diseases of seedlings which have been growing nor- 

 mally should not be confused with the simple wilting of seed- 

 lings in dry soil, or to the wilting due to the transfer of seed- 

 lings from a warm soil to a cold soil^ etc. 



In the winter of 1898 I received from a correspondent radishes 

 of marketable size which showed a soft rot of the crown, or ul- 

 cerated areas in the region of the crown, as shown in figure 55. 



