42 Diseases of Truck Crops 



Fungi which produce damping off as well as WILTS, 

 BLIGHTS, or ROTS in plants. 



DAMPING OFF 

 Caused by Pythium de Baryanum Hesse. 



This disease is very familiar to every grower of 

 plants. The trouble is peculiar to seedlings or very- 

 tender plants. It is prevalent in the greenhouse, the 

 hotbed, the cold frame, and frequently also in the 

 field. The trouble is induced by the presence of 

 definite parasitic fungi in the soil. They thrive best 

 when the land is continually damp, and the at- 

 mospheric temperature comparatively high. Damp- 

 ing off is also favored by thick sowing and too much 

 shade in the seed bed. 



Symptoms of Damping Off. Every experienced 

 trucker knows the disease when he sees it. Seedlings 

 freshly damped off are soft and water-soaked at the 

 base of the stem. If they are pulled they often break 

 off easily. A more careful examination shows that 

 the root system is entirely decayed by this time, al- 

 though the upper part of the stem and leaves may 

 still be green, possibly also fresh. The degree of 

 prostration in the seedlings is regulated by the 

 amount of moisture in the soil. If the amount of 

 moisture is slight, the seedlings will be flabby and 

 wilted before they topple over. With a high mois- 

 ture content, they are more firm, but become pros- 

 trate as soon as infection starts in. Damping off 



