122 Diseases of Truck Crops 



Control. All infected plants must be removed or 

 destroyed. To be successful this must be done early 

 enough before the winter spores of the fungus are 

 liberated in the soil. 



Damping off and Root Rot 



Caused by Pythium de Baryanum Hess. 



Symptoms. Damping off of the seedlings just as 

 they emerge from the ground is often a common 

 trouble under poor cultural conditions. The young 

 seedlings topple over and die in the characteristic 

 way so familiar to truckers. The greatest damage 

 occurs after heavy rains when a hard crust is formed 

 on the surface preventing the seedlings from emerg- 

 ing normally. On old and mature roots, Pythium de 

 Baryanum may cause a rot. According to Clinton, 1 

 the disease is found to be severe on mangels. A 

 peculiarity of the rot is that it seldom starts at the 

 top of the crown. The latter appears to be perfectly 

 healthy, although the leaves turn yellow, indicating 

 a diseased condition further down. Rotted roots 

 are found to be overrun by a varied flora, although 

 Pythium de Baryanum is the original cause of the 

 trouble. For a further description of the organism 

 see p. 43. 



Control. The disease is more prevalent during wet 

 weather, and in heavy soils which are poorly drained. 

 Thorough drainage of the land and careful cultiva- 



1 Clinton, G. P., Connecticut Agr. Expt. Sta. 39th. Ann. Rept.: 

 433-436, I9I5- 



