THE POTATO 193 



DRY ROT 



Dry rot, due to Fusarium oxysporum, has been 

 known in the potato world for a good many years, 

 but the real cause was not understood until re- 

 cently. A great deal of research work has been 

 done in Germany. 



This dry rot is a fungous disease that attacks the 

 potato plant through the root system, which not 

 only destroys the root hairs and secondary roots, 

 but penetrates the main roots, the tubers, and 

 later, when the plant is practically destroyed, the 

 stem is wilted. It also causes dry rot in potatoes 

 in storage. 



The disease is well distributed over the potato 

 districts of practically all potato producing coun- 

 tries. 



A vast amount of experimenting has been done 

 with the idea of finding the best way of com- 

 bating the pest. In "Bulletin 229" of the Ohio 

 Agricultural Experiment Station Thos. F. Manns 

 summarizes the results of their work. The things 

 he says about Ohio apply to any similar conditions : 



"1. The dry-rot fungus (Fusarium oxysporum, 

 Schlecht) of potato proves to be a field trouble 

 common in Ohio, which causes a blight and wilt of 

 the crop. 



"2. It produces a sick soil condition in potato 

 districts. 



"3. The field symptoms are characterized by a 

 cessation of growth, a yellowing of the foliage, with 

 an upward and inward rolling of the upper leaves, 

 accompanied by wilt during the heat of the day. 



"4. The sick soil conditions may reduce the 

 yield to 50 per cent, or more of an average crop. 



