252 



Diseases of Economic Plants 



just above the roots antl the failure of the plant to develop 

 normally. 



Damping-off due to Thielavia or other fungi may occur in 

 seed beds. The plants are attacked when very young, and 



Fig. 137. ^Tobacco roots showing effect of root-rot. 

 After Gilbert. 



death may result before they attain a height of more than 

 5-10 mm. In other cases of milder attack the roots alone are 

 invaded and the plants stunted. The tips of the rootlets 



